granicus.if.org Git - imagemagick/blob - MagickCore/shear.c

   1 /*
   2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   3 %                                                                             %
   4 %                                                                             %
   5 %                                                                             %
   6 %                      SSSSS  H   H  EEEEE   AAA    RRRR                      %
   7 %                      SS     H   H  E      A   A   R   R                     %
   8 %                       SSS   HHHHH  EEE    AAAAA   RRRR                      %
   9 %                         SS  H   H  E      A   A   R R                       %
  10 %                      SSSSS  H   H  EEEEE  A   A   R  R                      %
  11 %                                                                             %
  12 %                                                                             %
  13 %    MagickCore Methods to Shear or Rotate an Image by an Arbitrary Angle     %
  14 %                                                                             %
  15 %                               Software Design                               %
  16 %                                 John Cristy                                 %
  17 %                                  July 1992                                  %
  18 %                                                                             %
  19 %                                                                             %
  20 %  Copyright 1999-2011 ImageMagick Studio LLC, a non-profit organization      %
  21 %  dedicated to making software imaging solutions freely available.           %
  22 %                                                                             %
  23 %  You may not use this file except in compliance with the License.  You may  %
  24 %  obtain a copy of the License at                                            %
  25 %                                                                             %
  26 %    http://www.imagemagick.org/script/license.php                            %
  27 %                                                                             %
  28 %  Unless required by applicable law or agreed to in writing, software        %
  29 %  distributed under the License is distributed on an "AS IS" BASIS,          %
  30 %  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   %
  31 %  See the License for the specific language governing permissions and        %
  32 %  limitations under the License.                                             %
  33 %                                                                             %
  34 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  35 %
  36 %  The RotateImage, XShearImage, and YShearImage methods are based on the
  37 %  paper "A Fast Algorithm for General Raster Rotatation" by Alan W. Paeth,
  38 %  Graphics Interface '86 (Vancouver).  RotateImage is adapted from a similar
  39 %  method based on the Paeth paper written by Michael Halle of the Spatial
  40 %  Imaging Group, MIT Media Lab.
  41 %
  42 %
  43 */
  44 \f
  45 /*
  46   Include declarations.
  47 */
  48 #include "MagickCore/studio.h"
  49 #include "MagickCore/artifact.h"
  50 #include "MagickCore/attribute.h"
  51 #include "MagickCore/blob-private.h"
  52 #include "MagickCore/cache-private.h"
  53 #include "MagickCore/color-private.h"
  54 #include "MagickCore/colorspace-private.h"
  55 #include "MagickCore/composite.h"
  56 #include "MagickCore/composite-private.h"
  57 #include "MagickCore/decorate.h"
  58 #include "MagickCore/distort.h"
  59 #include "MagickCore/draw.h"
  60 #include "MagickCore/exception.h"
  61 #include "MagickCore/exception-private.h"
  62 #include "MagickCore/gem.h"
  63 #include "MagickCore/geometry.h"
  64 #include "MagickCore/image.h"
  65 #include "MagickCore/image-private.h"
  66 #include "MagickCore/memory_.h"
  67 #include "MagickCore/list.h"
  68 #include "MagickCore/monitor.h"
  69 #include "MagickCore/monitor-private.h"
  70 #include "MagickCore/pixel-accessor.h"
  71 #include "MagickCore/quantum.h"
  72 #include "MagickCore/resource_.h"
  73 #include "MagickCore/shear.h"
  74 #include "MagickCore/statistic.h"
  75 #include "MagickCore/string_.h"
  76 #include "MagickCore/string-private.h"
  77 #include "MagickCore/thread-private.h"
  78 #include "MagickCore/threshold.h"
  79 #include "MagickCore/transform.h"
  80 \f
  81 /*
  82 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  83 %                                                                             %
  84 %                                                                             %
  85 %                                                                             %
  86 %     A f f i n e T r a n s f o r m I m a g e                                 %
  87 %                                                                             %
  88 %                                                                             %
  89 %                                                                             %
  90 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  91 %
  92 %  AffineTransformImage() transforms an image as dictated by the affine matrix.
  93 %  It allocates the memory necessary for the new Image structure and returns
  94 %  a pointer to the new image.
  95 %
  96 %  The format of the AffineTransformImage method is:
  97 %
  98 %      Image *AffineTransformImage(const Image *image,
  99 %        AffineMatrix *affine_matrix,ExceptionInfo *exception)
 100 %
 101 %  A description of each parameter follows:
 102 %
 103 %    o image: the image.
 104 %
 105 %    o affine_matrix: the affine matrix.
 106 %
 107 %    o exception: return any errors or warnings in this structure.
 108 %
 109 */
 110 MagickExport Image *AffineTransformImage(const Image *image,
 111   const AffineMatrix *affine_matrix,ExceptionInfo *exception)
 112 {
 113   double
 114     distort[6];
 115
 116   Image
 117     *deskew_image;
 118
 119   /*
 120     Affine transform image.
 121   */
 122   assert(image->signature == MagickSignature);
 123   if (image->debug != MagickFalse)
 124     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
 125   assert(affine_matrix != (AffineMatrix *) NULL);
 126   assert(exception != (ExceptionInfo *) NULL);
 127   assert(exception->signature == MagickSignature);
 128   distort[0]=affine_matrix->sx;
 129   distort[1]=affine_matrix->rx;
 130   distort[2]=affine_matrix->ry;
 131   distort[3]=affine_matrix->sy;
 132   distort[4]=affine_matrix->tx;
 133   distort[5]=affine_matrix->ty;
 134   deskew_image=DistortImage(image,AffineProjectionDistortion,6,distort,
 135     MagickTrue,exception);
 136   return(deskew_image);
 137 }
 138 \f
 139 /*
 140 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 141 %                                                                             %
 142 %                                                                             %
 143 %                                                                             %
 144 +   C r o p T o F i t I m a g e                                               %
 145 %                                                                             %
 146 %                                                                             %
 147 %                                                                             %
 148 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 149 %
 150 %  CropToFitImage() crops the sheared image as determined by the bounding box
 151 %  as defined by width and height and shearing angles.
 152 %
 153 %  The format of the CropToFitImage method is:
 154 %
 155 %      MagickBooleanType CropToFitImage(Image **image,
 156 %        const MagickRealType x_shear,const MagickRealType x_shear,
 157 %        const MagickRealType width,const MagickRealType height,
 158 %        const MagickBooleanType rotate,ExceptionInfo *exception)
 159 %
 160 %  A description of each parameter follows.
 161 %
 162 %    o image: the image.
 163 %
 164 %    o x_shear, y_shear, width, height: Defines a region of the image to crop.
 165 %
 166 %    o exception: return any errors or warnings in this structure.
 167 %
 168 */
 169 static MagickBooleanType CropToFitImage(Image **image,
 170   const MagickRealType x_shear,const MagickRealType y_shear,
 171   const MagickRealType width,const MagickRealType height,
 172   const MagickBooleanType rotate,ExceptionInfo *exception)
 173 {
 174   Image
 175     *crop_image;
 176
 177   PointInfo
 178     extent[4],
 179     min,
 180     max;
 181
 182   RectangleInfo
 183     geometry,
 184     page;
 185
 186   register ssize_t
 187     i;
 188
 189   /*
 190     Calculate the rotated image size.
 191   */
 192   extent[0].x=(double) (-width/2.0);
 193   extent[0].y=(double) (-height/2.0);
 194   extent[1].x=(double) width/2.0;
 195   extent[1].y=(double) (-height/2.0);
 196   extent[2].x=(double) (-width/2.0);
 197   extent[2].y=(double) height/2.0;
 198   extent[3].x=(double) width/2.0;
 199   extent[3].y=(double) height/2.0;
 200   for (i=0; i < 4; i++)
 201   {
 202     extent[i].x+=x_shear*extent[i].y;
 203     extent[i].y+=y_shear*extent[i].x;
 204     if (rotate != MagickFalse)
 205       extent[i].x+=x_shear*extent[i].y;
 206     extent[i].x+=(double) (*image)->columns/2.0;
 207     extent[i].y+=(double) (*image)->rows/2.0;
 208   }
 209   min=extent[0];
 210   max=extent[0];
 211   for (i=1; i < 4; i++)
 212   {
 213     if (min.x > extent[i].x)
 214       min.x=extent[i].x;
 215     if (min.y > extent[i].y)
 216       min.y=extent[i].y;
 217     if (max.x < extent[i].x)
 218       max.x=extent[i].x;
 219     if (max.y < extent[i].y)
 220       max.y=extent[i].y;
 221   }
 222   geometry.x=(ssize_t) ceil(min.x-0.5);
 223   geometry.y=(ssize_t) ceil(min.y-0.5);
 224   geometry.width=(size_t) floor(max.x-min.x+0.5);
 225   geometry.height=(size_t) floor(max.y-min.y+0.5);
 226   page=(*image)->page;
 227   (void) ParseAbsoluteGeometry("0x0+0+0",&(*image)->page);
 228   crop_image=CropImage(*image,&geometry,exception);
 229   if (crop_image == (Image *) NULL)
 230     return(MagickFalse);
 231   crop_image->page=page;
 232   *image=DestroyImage(*image);
 233   *image=crop_image;
 234   return(MagickTrue);
 235 }
 236 \f
 237 /*
 238 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 239 %                                                                             %
 240 %                                                                             %
 241 %                                                                             %
 242 %     D e s k e w I m a g e                                                   %
 243 %                                                                             %
 244 %                                                                             %
 245 %                                                                             %
 246 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 247 %
 248 %  DeskewImage() removes skew from the image.  Skew is an artifact that
 249 %  occurs in scanned images because of the camera being misaligned,
 250 %  imperfections in the scanning or surface, or simply because the paper was
 251 %  not placed completely flat when scanned.
 252 %
 253 %  The format of the DeskewImage method is:
 254 %
 255 %      Image *DeskewImage(const Image *image,const double threshold,
 256 %        ExceptionInfo *exception)
 257 %
 258 %  A description of each parameter follows:
 259 %
 260 %    o image: the image.
 261 %
 262 %    o threshold: separate background from foreground.
 263 %
 264 %    o exception: return any errors or warnings in this structure.
 265 %
 266 */
 267
 268 typedef struct _RadonInfo
 269 {
 270   CacheType
 271     type;
 272
 273   size_t
 274     width,
 275     height;
 276
 277   MagickSizeType
 278     length;
 279
 280   MagickBooleanType
 281     mapped;
 282
 283   char
 284     path[MaxTextExtent];
 285
 286   int
 287     file;
 288
 289   unsigned short
 290     *cells;
 291 } RadonInfo;
 292
 293 static RadonInfo *DestroyRadonInfo(RadonInfo *radon_info)
 294 {
 295   assert(radon_info != (RadonInfo *) NULL);
 296   switch (radon_info->type)
 297   {
 298     case MemoryCache:
 299     {
 300       if (radon_info->mapped == MagickFalse)
 301         radon_info->cells=(unsigned short *) RelinquishMagickMemory(
 302           radon_info->cells);
 303       else
 304         radon_info->cells=(unsigned short *) UnmapBlob(radon_info->cells,
 305           (size_t) radon_info->length);
 306       RelinquishMagickResource(MemoryResource,radon_info->length);
 307       break;
 308     }
 309     case MapCache:
 310     {
 311       radon_info->cells=(unsigned short *) UnmapBlob(radon_info->cells,(size_t)
 312         radon_info->length);
 313       RelinquishMagickResource(MapResource,radon_info->length);
 314     }
 315     case DiskCache:
 316     {
 317       if (radon_info->file != -1)
 318         (void) close(radon_info->file);
 319       (void) RelinquishUniqueFileResource(radon_info->path);
 320       RelinquishMagickResource(DiskResource,radon_info->length);
 321       break;
 322     }
 323     default:
 324       break;
 325   }
 326   return((RadonInfo *) RelinquishMagickMemory(radon_info));
 327 }
 328
 329 static MagickBooleanType ResetRadonCells(RadonInfo *radon_info)
 330 {
 331   register ssize_t
 332     x;
 333
 334   ssize_t
 335     count,
 336     y;
 337
 338   unsigned short
 339     value;
 340
 341   if (radon_info->type != DiskCache)
 342     {
 343       (void) ResetMagickMemory(radon_info->cells,0,(size_t) radon_info->length);
 344       return(MagickTrue);
 345     }
 346   value=0;
 347   (void) lseek(radon_info->file,0,SEEK_SET);
 348   for (y=0; y < (ssize_t) radon_info->height; y++)
 349   {
 350     for (x=0; x < (ssize_t) radon_info->width; x++)
 351     {
 352       count=write(radon_info->file,&value,sizeof(*radon_info->cells));
 353       if (count != (ssize_t) sizeof(*radon_info->cells))
 354         break;
 355     }
 356     if (x < (ssize_t) radon_info->width)
 357       break;
 358   }
 359   return(y < (ssize_t) radon_info->height ? MagickFalse : MagickTrue);
 360 }
 361
 362 static RadonInfo *AcquireRadonInfo(const Image *image,const size_t width,
 363   const size_t height,ExceptionInfo *exception)
 364 {
 365   MagickBooleanType
 366     status;
 367
 368   RadonInfo
 369     *radon_info;
 370
 371   radon_info=(RadonInfo *) AcquireMagickMemory(sizeof(*radon_info));
 372   if (radon_info == (RadonInfo *) NULL)
 373     return((RadonInfo *) NULL);
 374   (void) ResetMagickMemory(radon_info,0,sizeof(*radon_info));
 375   radon_info->width=width;
 376   radon_info->height=height;
 377   radon_info->length=(MagickSizeType) width*height*sizeof(*radon_info->cells);
 378   radon_info->type=MemoryCache;
 379   status=AcquireMagickResource(AreaResource,radon_info->length);
 380   if ((status != MagickFalse) &&
 381       (radon_info->length == (MagickSizeType) ((size_t) radon_info->length)))
 382     {
 383       status=AcquireMagickResource(MemoryResource,radon_info->length);
 384       if (status != MagickFalse)
 385         {
 386           radon_info->mapped=MagickFalse;
 387           radon_info->cells=(unsigned short *) AcquireMagickMemory((size_t)
 388             radon_info->length);
 389           if (radon_info->cells == (unsigned short *) NULL)
 390             {
 391               radon_info->mapped=MagickTrue;
 392               radon_info->cells=(unsigned short *) MapBlob(-1,IOMode,0,(size_t)
 393                 radon_info->length);
 394             }
 395           if (radon_info->cells == (unsigned short *) NULL)
 396             RelinquishMagickResource(MemoryResource,radon_info->length);
 397         }
 398     }
 399   radon_info->file=(-1);
 400   if (radon_info->cells == (unsigned short *) NULL)
 401     {
 402       status=AcquireMagickResource(DiskResource,radon_info->length);
 403       if (status == MagickFalse)
 404         {
 405           (void) ThrowMagickException(exception,GetMagickModule(),CacheError,
 406             "CacheResourcesExhausted","`%s'",image->filename);
 407           return(DestroyRadonInfo(radon_info));
 408         }
 409       radon_info->type=DiskCache;
 410       (void) AcquireMagickResource(MemoryResource,radon_info->length);
 411       radon_info->file=AcquireUniqueFileResource(radon_info->path);
 412       if (radon_info->file == -1)
 413         return(DestroyRadonInfo(radon_info));
 414       status=AcquireMagickResource(MapResource,radon_info->length);
 415       if (status != MagickFalse)
 416         {
 417           status=ResetRadonCells(radon_info);
 418           if (status != MagickFalse)
 419             {
 420               radon_info->cells=(unsigned short *) MapBlob(radon_info->file,
 421                 IOMode,0,(size_t) radon_info->length);
 422               if (radon_info->cells != (unsigned short *) NULL)
 423                 radon_info->type=MapCache;
 424               else
 425                 RelinquishMagickResource(MapResource,radon_info->length);
 426             }
 427         }
 428     }
 429   return(radon_info);
 430 }
 431
 432 static inline size_t MagickMin(const size_t x,const size_t y)
 433 {
 434   if (x < y)
 435     return(x);
 436   return(y);
 437 }
 438
 439 static inline ssize_t ReadRadonCell(const RadonInfo *radon_info,
 440   const MagickOffsetType offset,const size_t length,unsigned char *buffer)
 441 {
 442   register ssize_t
 443     i;
 444
 445   ssize_t
 446     count;
 447
 448 #if !defined(MAGICKCORE_HAVE_PPREAD)
 449 #if defined(MAGICKCORE_OPENMP_SUPPORT)
 450   #pragma omp critical (MagickCore_ReadRadonCell)
 451 #endif
 452   {
 453     i=(-1);
 454     if (lseek(radon_info->file,offset,SEEK_SET) >= 0)
 455       {
 456 #endif
 457         count=0;
 458         for (i=0; i < (ssize_t) length; i+=count)
 459         {
 460 #if !defined(MAGICKCORE_HAVE_PPREAD)
 461           count=read(radon_info->file,buffer+i,MagickMin(length-i,(size_t)
 462             SSIZE_MAX));
 463 #else
 464           count=pread(radon_info->file,buffer+i,MagickMin(length-i,(size_t)
 465             SSIZE_MAX),offset+i);
 466 #endif
 467           if (count > 0)
 468             continue;
 469           count=0;
 470           if (errno != EINTR)
 471             {
 472               i=(-1);
 473               break;
 474             }
 475         }
 476 #if !defined(MAGICKCORE_HAVE_PPREAD)
 477       }
 478   }
 479 #endif
 480   return(i);
 481 }
 482
 483 static inline ssize_t WriteRadonCell(const RadonInfo *radon_info,
 484   const MagickOffsetType offset,const size_t length,const unsigned char *buffer)
 485 {
 486   register ssize_t
 487     i;
 488
 489   ssize_t
 490     count;
 491
 492 #if !defined(MAGICKCORE_HAVE_PWRITE)
 493 #if defined(MAGICKCORE_OPENMP_SUPPORT)
 494   #pragma omp critical (MagickCore_WriteRadonCell)
 495 #endif
 496   {
 497     if (lseek(radon_info->file,offset,SEEK_SET) >= 0)
 498       {
 499 #endif
 500         count=0;
 501         for (i=0; i < (ssize_t) length; i+=count)
 502         {
 503 #if !defined(MAGICKCORE_HAVE_PWRITE)
 504           count=write(radon_info->file,buffer+i,MagickMin(length-i,(size_t)
 505             SSIZE_MAX));
 506 #else
 507           count=pwrite(radon_info->file,buffer+i,MagickMin(length-i,(size_t)
 508             SSIZE_MAX),offset+i);
 509 #endif
 510           if (count > 0)
 511             continue;
 512           count=0;
 513           if (errno != EINTR)
 514             {
 515               i=(-1);
 516               break;
 517             }
 518         }
 519 #if !defined(MAGICKCORE_HAVE_PWRITE)
 520       }
 521   }
 522 #endif
 523   return(i);
 524 }
 525
 526 static inline unsigned short GetRadonCell(const RadonInfo *radon_info,
 527   const ssize_t x,const ssize_t y)
 528 {
 529   MagickOffsetType
 530     i;
 531
 532   unsigned short
 533     value;
 534
 535   i=(MagickOffsetType) radon_info->height*x+y;
 536   if ((i < 0) ||
 537       ((MagickSizeType) (i*sizeof(*radon_info->cells)) >= radon_info->length))
 538     return(0);
 539   if (radon_info->type != DiskCache)
 540     return(radon_info->cells[i]);
 541   value=0;
 542   (void) ReadRadonCell(radon_info,i*sizeof(*radon_info->cells),
 543     sizeof(*radon_info->cells),(unsigned char *) &value);
 544   return(value);
 545 }
 546
 547 static inline MagickBooleanType SetRadonCell(const RadonInfo *radon_info,
 548   const ssize_t x,const ssize_t y,const unsigned short value)
 549 {
 550   MagickOffsetType
 551     i;
 552
 553   ssize_t
 554     count;
 555
 556   i=(MagickOffsetType) radon_info->height*x+y;
 557   if ((i < 0) ||
 558       ((MagickSizeType) (i*sizeof(*radon_info->cells)) >= radon_info->length))
 559     return(MagickFalse);
 560   if (radon_info->type != DiskCache)
 561     {
 562       radon_info->cells[i]=value;
 563       return(MagickTrue);
 564     }
 565   count=WriteRadonCell(radon_info,i*sizeof(*radon_info->cells),
 566     sizeof(*radon_info->cells),(const unsigned char *) &value);
 567   if (count != (ssize_t) sizeof(*radon_info->cells))
 568     return(MagickFalse);
 569   return(MagickTrue);
 570 }
 571
 572 static void RadonProjection(RadonInfo *source_cells,
 573   RadonInfo *destination_cells,const ssize_t sign,size_t *projection)
 574 {
 575   RadonInfo
 576     *swap;
 577
 578   register ssize_t
 579     x;
 580
 581   register RadonInfo
 582     *p,
 583     *q;
 584
 585   size_t
 586     step;
 587
 588   p=source_cells;
 589   q=destination_cells;
 590   for (step=1; step < p->width; step*=2)
 591   {
 592     for (x=0; x < (ssize_t) p->width; x+=2*(ssize_t) step)
 593     {
 594       register ssize_t
 595         i;
 596
 597       ssize_t
 598         y;
 599
 600       unsigned short
 601         cell;
 602
 603       for (i=0; i < (ssize_t) step; i++)
 604       {
 605         for (y=0; y < (ssize_t) (p->height-i-1); y++)
 606         {
 607           cell=GetRadonCell(p,x+i,y);
 608           (void) SetRadonCell(q,x+2*i,y,cell+GetRadonCell(p,x+i+(ssize_t)
 609             step,y+i));
 610           (void) SetRadonCell(q,x+2*i+1,y,cell+GetRadonCell(p,x+i+(ssize_t)
 611             step,y+i+1));
 612         }
 613         for ( ; y < (ssize_t) (p->height-i); y++)
 614         {
 615           cell=GetRadonCell(p,x+i,y);
 616           (void) SetRadonCell(q,x+2*i,y,cell+GetRadonCell(p,x+i+(ssize_t) step,
 617             y+i));
 618           (void) SetRadonCell(q,x+2*i+1,y,cell);
 619         }
 620         for ( ; y < (ssize_t) p->height; y++)
 621         {
 622           cell=GetRadonCell(p,x+i,y);
 623           (void) SetRadonCell(q,x+2*i,y,cell);
 624           (void) SetRadonCell(q,x+2*i+1,y,cell);
 625         }
 626       }
 627     }
 628     swap=p;
 629     p=q;
 630     q=swap;
 631   }
 632 #if defined(MAGICKCORE_OPENMP_SUPPORT)
 633   #pragma omp parallel for schedule(dynamic,4)
 634 #endif
 635   for (x=0; x < (ssize_t) p->width; x++)
 636   {
 637     register ssize_t
 638       y;
 639
 640     size_t
 641       sum;
 642
 643     sum=0;
 644     for (y=0; y < (ssize_t) (p->height-1); y++)
 645     {
 646       ssize_t
 647         delta;
 648
 649       delta=GetRadonCell(p,x,y)-(ssize_t) GetRadonCell(p,x,y+1);
 650       sum+=delta*delta;
 651     }
 652     projection[p->width+sign*x-1]=sum;
 653   }
 654 }
 655
 656 static MagickBooleanType RadonTransform(const Image *image,
 657   const double threshold,size_t *projection,ExceptionInfo *exception)
 658 {
 659   CacheView
 660     *image_view;
 661
 662   MagickBooleanType
 663     status;
 664
 665   RadonInfo
 666     *destination_cells,
 667     *source_cells;
 668
 669   register ssize_t
 670     i;
 671
 672   size_t
 673     count,
 674     width;
 675
 676   ssize_t
 677     y;
 678
 679   unsigned char
 680     byte;
 681
 682   unsigned short
 683     bits[256];
 684
 685   for (width=1; width < ((image->columns+7)/8); width<<=1) ;
 686   source_cells=AcquireRadonInfo(image,width,image->rows,exception);
 687   destination_cells=AcquireRadonInfo(image,width,image->rows,exception);
 688   if ((source_cells == (RadonInfo *) NULL) ||
 689       (destination_cells == (RadonInfo *) NULL))
 690     {
 691       if (destination_cells != (RadonInfo *) NULL)
 692         destination_cells=DestroyRadonInfo(destination_cells);
 693       if (source_cells != (RadonInfo *) NULL)
 694         source_cells=DestroyRadonInfo(source_cells);
 695       return(MagickFalse);
 696     }
 697   if (ResetRadonCells(source_cells) == MagickFalse)
 698     {
 699       destination_cells=DestroyRadonInfo(destination_cells);
 700       source_cells=DestroyRadonInfo(source_cells);
 701       return(MagickFalse);
 702     }
 703   for (i=0; i < 256; i++)
 704   {
 705     byte=(unsigned char) i;
 706     for (count=0; byte != 0; byte>>=1)
 707       count+=byte & 0x01;
 708     bits[i]=(unsigned short) count;
 709   }
 710   status=MagickTrue;
 711   image_view=AcquireCacheView(image);
 712 #if defined(MAGICKCORE_OPENMP_SUPPORT)
 713   #pragma omp parallel for schedule(dynamic,4) shared(status)
 714 #endif
 715   for (y=0; y < (ssize_t) image->rows; y++)
 716   {
 717     register const Quantum
 718       *restrict p;
 719
 720     register ssize_t
 721       i,
 722       x;
 723
 724     size_t
 725       bit,
 726       byte;
 727
 728     if (status == MagickFalse)
 729       continue;
 730     p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
 731     if (p == (const Quantum *) NULL)
 732       {
 733         status=MagickFalse;
 734         continue;
 735       }
 736     bit=0;
 737     byte=0;
 738     i=(ssize_t) (image->columns+7)/8;
 739     for (x=0; x < (ssize_t) image->columns; x++)
 740     {
 741       byte<<=1;
 742       if (((MagickRealType) GetPixelRed(image,p) < threshold) ||
 743           ((MagickRealType) GetPixelGreen(image,p) < threshold) ||
 744           ((MagickRealType) GetPixelBlue(image,p) < threshold))
 745         byte|=0x01;
 746       bit++;
 747       if (bit == 8)
 748         {
 749           (void) SetRadonCell(source_cells,--i,y,bits[byte]);
 750           bit=0;
 751           byte=0;
 752         }
 753       p+=GetPixelChannels(image);
 754     }
 755     if (bit != 0)
 756       {
 757         byte<<=(8-bit);
 758         (void) SetRadonCell(source_cells,--i,y,bits[byte]);
 759       }
 760   }
 761   RadonProjection(source_cells,destination_cells,-1,projection);
 762   (void) ResetRadonCells(source_cells);
 763 #if defined(MAGICKCORE_OPENMP_SUPPORT)
 764   #pragma omp parallel for schedule(dynamic,4) shared(status)
 765 #endif
 766   for (y=0; y < (ssize_t) image->rows; y++)
 767   {
 768     register const Quantum
 769       *restrict p;
 770
 771     register ssize_t
 772       i,
 773       x;
 774
 775     size_t
 776       bit,
 777       byte;
 778
 779     if (status == MagickFalse)
 780       continue;
 781     p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
 782     if (p == (const Quantum *) NULL)
 783       {
 784         status=MagickFalse;
 785         continue;
 786       }
 787     bit=0;
 788     byte=0;
 789     i=0;
 790     for (x=0; x < (ssize_t) image->columns; x++)
 791     {
 792       byte<<=1;
 793       if (((MagickRealType) GetPixelRed(image,p) < threshold) ||
 794           ((MagickRealType) GetPixelGreen(image,p) < threshold) ||
 795           ((MagickRealType) GetPixelBlue(image,p) < threshold))
 796         byte|=0x01;
 797       bit++;
 798       if (bit == 8)
 799         {
 800           (void) SetRadonCell(source_cells,i++,y,bits[byte]);
 801           bit=0;
 802           byte=0;
 803         }
 804       p+=GetPixelChannels(image);
 805     }
 806     if (bit != 0)
 807       {
 808         byte<<=(8-bit);
 809         (void) SetRadonCell(source_cells,i++,y,bits[byte]);
 810       }
 811   }
 812   RadonProjection(source_cells,destination_cells,1,projection);
 813   image_view=DestroyCacheView(image_view);
 814   destination_cells=DestroyRadonInfo(destination_cells);
 815   source_cells=DestroyRadonInfo(source_cells);
 816   return(MagickTrue);
 817 }
 818
 819 static void GetImageBackgroundColor(Image *image,const ssize_t offset,
 820   ExceptionInfo *exception)
 821 {
 822   CacheView
 823     *image_view;
 824
 825   PixelInfo
 826     background;
 827
 828   MagickRealType
 829     count;
 830
 831   ssize_t
 832     y;
 833
 834   /*
 835     Compute average background color.
 836   */
 837   if (offset <= 0)
 838     return;
 839   GetPixelInfo(image,&background);
 840   count=0.0;
 841   image_view=AcquireCacheView(image);
 842   for (y=0; y < (ssize_t) image->rows; y++)
 843   {
 844     register const Quantum
 845       *restrict p;
 846
 847     register ssize_t
 848       x;
 849
 850     if ((y >= offset) && (y < ((ssize_t) image->rows-offset)))
 851       continue;
 852     p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
 853     if (p == (const Quantum *) NULL)
 854       continue;
 855     for (x=0; x < (ssize_t) image->columns; x++)
 856     {
 857       if ((x >= offset) && (x < ((ssize_t) image->columns-offset)))
 858         continue;
 859       background.red+=QuantumScale*GetPixelRed(image,p);
 860       background.green+=QuantumScale*GetPixelGreen(image,p);
 861       background.blue+=QuantumScale*GetPixelBlue(image,p);
 862       background.alpha+=QuantumScale*GetPixelAlpha(image,p);
 863       count++;
 864       p+=GetPixelChannels(image);
 865     }
 866   }
 867   image_view=DestroyCacheView(image_view);
 868   image->background_color.red=ClampToQuantum((MagickRealType) QuantumRange*
 869     background.red/count);
 870   image->background_color.green=ClampToQuantum((MagickRealType) QuantumRange*
 871     background.green/count);
 872   image->background_color.blue=ClampToQuantum((MagickRealType) QuantumRange*
 873     background.blue/count);
 874   image->background_color.alpha=ClampToQuantum((MagickRealType) QuantumRange*
 875     background.alpha/count);
 876 }
 877
 878 MagickExport Image *DeskewImage(const Image *image,const double threshold,
 879   ExceptionInfo *exception)
 880 {
 881   AffineMatrix
 882     affine_matrix;
 883
 884   const char
 885     *artifact;
 886
 887   double
 888     degrees;
 889
 890   Image
 891     *clone_image,
 892     *crop_image,
 893     *deskew_image,
 894     *median_image;
 895
 896   MagickBooleanType
 897     status;
 898
 899   RectangleInfo
 900     geometry;
 901
 902   register ssize_t
 903     i;
 904
 905   size_t
 906     max_projection,
 907     *projection,
 908     width;
 909
 910   ssize_t
 911     skew;
 912
 913   /*
 914     Compute deskew angle.
 915   */
 916   for (width=1; width < ((image->columns+7)/8); width<<=1) ;
 917   projection=(size_t *) AcquireQuantumMemory((size_t) (2*width-1),
 918     sizeof(*projection));
 919   if (projection == (size_t *) NULL)
 920     ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
 921   status=RadonTransform(image,threshold,projection,exception);
 922   if (status == MagickFalse)
 923     {
 924       projection=(size_t *) RelinquishMagickMemory(projection);
 925       ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
 926     }
 927   max_projection=0;
 928   skew=0;
 929   for (i=0; i < (ssize_t) (2*width-1); i++)
 930   {
 931     if (projection[i] > max_projection)
 932       {
 933         skew=i-(ssize_t) width+1;
 934         max_projection=projection[i];
 935       }
 936   }
 937   projection=(size_t *) RelinquishMagickMemory(projection);
 938   /*
 939     Deskew image.
 940   */
 941   clone_image=CloneImage(image,0,0,MagickTrue,exception);
 942   if (clone_image == (Image *) NULL)
 943     return((Image *) NULL);
 944   (void) SetImageVirtualPixelMethod(clone_image,BackgroundVirtualPixelMethod);
 945   degrees=RadiansToDegrees(-atan((double) skew/width/8));
 946   if (image->debug != MagickFalse)
 947     (void) LogMagickEvent(TransformEvent,GetMagickModule(),
 948       "  Deskew angle: %g",degrees);
 949   affine_matrix.sx=cos(DegreesToRadians(fmod((double) degrees,360.0)));
 950   affine_matrix.rx=sin(DegreesToRadians(fmod((double) degrees,360.0)));
 951   affine_matrix.ry=(-sin(DegreesToRadians(fmod((double) degrees,360.0))));
 952   affine_matrix.sy=cos(DegreesToRadians(fmod((double) degrees,360.0)));
 953   affine_matrix.tx=0.0;
 954   affine_matrix.ty=0.0;
 955   artifact=GetImageArtifact(image,"deskew:auto-crop");
 956   if (artifact == (const char *) NULL)
 957     {
 958       deskew_image=AffineTransformImage(clone_image,&affine_matrix,exception);
 959       clone_image=DestroyImage(clone_image);
 960       return(deskew_image);
 961     }
 962   /*
 963     Auto-crop image.
 964   */
 965   GetImageBackgroundColor(clone_image,(ssize_t) StringToLong(artifact),
 966     exception);
 967   deskew_image=AffineTransformImage(clone_image,&affine_matrix,exception);
 968   clone_image=DestroyImage(clone_image);
 969   if (deskew_image == (Image *) NULL)
 970     return((Image *) NULL);
 971   median_image=StatisticImage(deskew_image,MedianStatistic,3,3,exception);
 972   if (median_image == (Image *) NULL)
 973     {
 974       deskew_image=DestroyImage(deskew_image);
 975       return((Image *) NULL);
 976     }
 977   geometry=GetImageBoundingBox(median_image,exception);
 978   median_image=DestroyImage(median_image);
 979   if (image->debug != MagickFalse)
 980     (void) LogMagickEvent(TransformEvent,GetMagickModule(),"  Deskew geometry: "
 981       "%.20gx%.20g%+.20g%+.20g",(double) geometry.width,(double)
 982       geometry.height,(double) geometry.x,(double) geometry.y);
 983   crop_image=CropImage(deskew_image,&geometry,exception);
 984   deskew_image=DestroyImage(deskew_image);
 985   return(crop_image);
 986 }
 987 \f
 988 /*
 989 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 990 %                                                                             %
 991 %                                                                             %
 992 %                                                                             %
 993 +   I n t e g r a l R o t a t e I m a g e                                     %
 994 %                                                                             %
 995 %                                                                             %
 996 %                                                                             %
 997 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 998 %
 999 %  IntegralRotateImage() rotates the image an integral of 90 degrees.  It
1000 %  allocates the memory necessary for the new Image structure and returns a
1001 %  pointer to the rotated image.
1002 %
1003 %  The format of the IntegralRotateImage method is:
1004 %
1005 %      Image *IntegralRotateImage(const Image *image,size_t rotations,
1006 %        ExceptionInfo *exception)
1007 %
1008 %  A description of each parameter follows.
1009 %
1010 %    o image: the image.
1011 %
1012 %    o rotations: Specifies the number of 90 degree rotations.
1013 %
1014 */
1015 static Image *IntegralRotateImage(const Image *image,size_t rotations,
1016   ExceptionInfo *exception)
1017 {
1018 #define RotateImageTag  "Rotate/Image"
1019
1020   CacheView
1021     *image_view,
1022     *rotate_view;
1023
1024   Image
1025     *rotate_image;
1026
1027   MagickBooleanType
1028     status;
1029
1030   MagickOffsetType
1031     progress;
1032
1033   RectangleInfo
1034     page;
1035
1036   ssize_t
1037     y;
1038
1039   /*
1040     Initialize rotated image attributes.
1041   */
1042   assert(image != (Image *) NULL);
1043   page=image->page;
1044   rotations%=4;
1045   if (rotations == 0)
1046     return(CloneImage(image,0,0,MagickTrue,exception));
1047   if ((rotations == 1) || (rotations == 3))
1048     rotate_image=CloneImage(image,image->rows,image->columns,MagickTrue,
1049       exception);
1050   else
1051     rotate_image=CloneImage(image,image->columns,image->rows,MagickTrue,
1052       exception);
1053   if (rotate_image == (Image *) NULL)
1054     return((Image *) NULL);
1055   /*
1056     Integral rotate the image.
1057   */
1058   status=MagickTrue;
1059   progress=0;
1060   image_view=AcquireCacheView(image);
1061   rotate_view=AcquireCacheView(rotate_image);
1062   switch (rotations)
1063   {
1064     case 0:
1065     {
1066       /*
1067         Rotate 0 degrees.
1068       */
1069       break;
1070     }
1071     case 1:
1072     {
1073       size_t
1074         tile_height,
1075         tile_width;
1076
1077       ssize_t
1078         tile_y;
1079
1080       /*
1081         Rotate 90 degrees.
1082       */
1083       GetPixelCacheTileSize(image,&tile_width,&tile_height);
1084       for (tile_y=0; tile_y < (ssize_t) image->rows; tile_y+=(ssize_t) tile_height)
1085       {
1086         register ssize_t
1087           tile_x;
1088
1089         if (status == MagickFalse)
1090           continue;
1091         for (tile_x=0; tile_x < (ssize_t) image->columns; tile_x+=(ssize_t) tile_width)
1092         {
1093           MagickBooleanType
1094             sync;
1095
1096           register const Quantum
1097             *restrict p;
1098
1099           register ssize_t
1100             y;
1101
1102           register Quantum
1103             *restrict q;
1104
1105           size_t
1106             height,
1107             width;
1108
1109           width=tile_width;
1110           if ((tile_x+(ssize_t) tile_width) > (ssize_t) image->columns)
1111             width=(size_t) (tile_width-(tile_x+tile_width-image->columns));
1112           height=tile_height;
1113           if ((tile_y+(ssize_t) tile_height) > (ssize_t) image->rows)
1114             height=(size_t) (tile_height-(tile_y+tile_height-image->rows));
1115           p=GetCacheViewVirtualPixels(image_view,tile_x,tile_y,width,height,
1116             exception);
1117           if (p == (const Quantum *) NULL)
1118             {
1119               status=MagickFalse;
1120               break;
1121             }
1122 #if defined(MAGICKCORE_OPENMP_SUPPORT)
1123           #pragma omp parallel for schedule(static,1) shared(progress, status)
1124 #endif
1125           for (y=0; y < (ssize_t) width; y++)
1126           {
1127             register const Quantum
1128               *restrict tile_pixels;
1129
1130             register ssize_t
1131               x;
1132
1133             if (status == MagickFalse)
1134               continue;
1135             q=QueueCacheViewAuthenticPixels(rotate_view,(ssize_t)
1136               (rotate_image->columns-(tile_y+height)),y+tile_x,height,1,
1137               exception);
1138             if (q == (Quantum *) NULL)
1139               {
1140                 status=MagickFalse;
1141                 continue;
1142               }
1143             tile_pixels=p+((height-1)*width+y)*GetPixelChannels(image);
1144             for (x=0; x < (ssize_t) height; x++)
1145             {
1146               register ssize_t
1147                 i;
1148
1149               for (i=0; i < (ssize_t) GetPixelChannels(image); i++)
1150               {
1151                 PixelChannel
1152                   channel;
1153
1154                 PixelTrait
1155                   rotate_traits,
1156                   traits;
1157
1158                 traits=GetPixelChannelMapTraits(image,(PixelChannel) i);
1159                 channel=GetPixelChannelMapChannel(image,(PixelChannel) i);
1160                 rotate_traits=GetPixelChannelMapTraits(rotate_image,channel);
1161                 if ((traits == UndefinedPixelTrait) ||
1162                     (rotate_traits == UndefinedPixelTrait))
1163                   continue;
1164                 if ((rotate_traits & CopyPixelTrait) != 0)
1165                   {
1166                     q[channel]=tile_pixels[i];
1167                     continue;
1168                   }
1169                 q[channel]=tile_pixels[i];
1170               }
1171               tile_pixels-=width*GetPixelChannels(image);
1172               q+=GetPixelChannels(rotate_image);
1173             }
1174             sync=SyncCacheViewAuthenticPixels(rotate_view,exception);
1175             if (sync == MagickFalse)
1176               status=MagickFalse;
1177           }
1178         }
1179         if (image->progress_monitor != (MagickProgressMonitor) NULL)
1180           {
1181             MagickBooleanType
1182               proceed;
1183
1184             proceed=SetImageProgress(image,RotateImageTag,progress+=tile_height,
1185               image->rows);
1186             if (proceed == MagickFalse)
1187               status=MagickFalse;
1188           }
1189       }
1190       (void) SetImageProgress(image,RotateImageTag,(MagickOffsetType)
1191         image->rows-1,image->rows);
1192       Swap(page.width,page.height);
1193       Swap(page.x,page.y);
1194       if (page.width != 0)
1195         page.x=(ssize_t) (page.width-rotate_image->columns-page.x);
1196       break;
1197     }
1198     case 2:
1199     {
1200       /*
1201         Rotate 180 degrees.
1202       */
1203 #if defined(MAGICKCORE_OPENMP_SUPPORT)
1204   #pragma omp parallel for schedule(static,8) shared(progress,status)
1205 #endif
1206       for (y=0; y < (ssize_t) image->rows; y++)
1207       {
1208         MagickBooleanType
1209           sync;
1210
1211         register const Quantum
1212           *restrict p;
1213
1214         register ssize_t
1215           x;
1216
1217         register Quantum
1218           *restrict q;
1219
1220         if (status == MagickFalse)
1221           continue;
1222         p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
1223         q=QueueCacheViewAuthenticPixels(rotate_view,0,(ssize_t) (image->rows-y-
1224           1),image->columns,1,exception);
1225         if ((p == (const Quantum *) NULL) || (q == (Quantum *) NULL))
1226           {
1227             status=MagickFalse;
1228             continue;
1229           }
1230         q+=GetPixelChannels(rotate_image)*image->columns;
1231         for (x=0; x < (ssize_t) image->columns; x++)
1232         {
1233           register ssize_t
1234             i;
1235
1236           q-=GetPixelChannels(rotate_image);
1237           for (i=0; i < (ssize_t) GetPixelChannels(image); i++)
1238           {
1239             PixelChannel
1240               channel;
1241
1242             PixelTrait
1243               rotate_traits,
1244               traits;
1245
1246             traits=GetPixelChannelMapTraits(image,(PixelChannel) i);
1247             channel=GetPixelChannelMapChannel(image,(PixelChannel) i);
1248             rotate_traits=GetPixelChannelMapTraits(rotate_image,channel);
1249             if ((traits == UndefinedPixelTrait) ||
1250                 (rotate_traits == UndefinedPixelTrait))
1251               continue;
1252             if ((rotate_traits & CopyPixelTrait) != 0)
1253               {
1254                 q[channel]=p[i];
1255                 continue;
1256               }
1257             q[channel]=p[i];
1258           }
1259           p+=GetPixelChannels(image);
1260         }
1261         sync=SyncCacheViewAuthenticPixels(rotate_view,exception);
1262         if (sync == MagickFalse)
1263           status=MagickFalse;
1264         if (image->progress_monitor != (MagickProgressMonitor) NULL)
1265           {
1266             MagickBooleanType
1267               proceed;
1268
1269             proceed=SetImageProgress(image,RotateImageTag,progress++,
1270               image->rows);
1271             if (proceed == MagickFalse)
1272               status=MagickFalse;
1273           }
1274       }
1275       if (page.width != 0)
1276         page.x=(ssize_t) (page.width-rotate_image->columns-page.x);
1277       if (page.height != 0)
1278         page.y=(ssize_t) (page.height-rotate_image->rows-page.y);
1279       break;
1280     }
1281     case 3:
1282     {
1283       size_t
1284         tile_height,
1285         tile_width;
1286
1287       ssize_t
1288         tile_y;
1289
1290       /*
1291         Rotate 270 degrees.
1292       */
1293       GetPixelCacheTileSize(image,&tile_width,&tile_height);
1294       for (tile_y=0; tile_y < (ssize_t) image->rows; tile_y+=(ssize_t) tile_height)
1295       {
1296         register ssize_t
1297           tile_x;
1298
1299         if (status == MagickFalse)
1300           continue;
1301         for (tile_x=0; tile_x < (ssize_t) image->columns; tile_x+=(ssize_t) tile_width)
1302         {
1303           MagickBooleanType
1304             sync;
1305
1306           register const Quantum
1307             *restrict p;
1308
1309           register ssize_t
1310             y;
1311
1312           register Quantum
1313             *restrict q;
1314
1315           size_t
1316             height,
1317             width;
1318
1319           width=tile_width;
1320           if ((tile_x+(ssize_t) tile_width) > (ssize_t) image->columns)
1321             width=(size_t) (tile_width-(tile_x+tile_width-image->columns));
1322           height=tile_height;
1323           if ((tile_y+(ssize_t) tile_height) > (ssize_t) image->rows)
1324             height=(size_t) (tile_height-(tile_y+tile_height-image->rows));
1325           p=GetCacheViewVirtualPixels(image_view,tile_x,tile_y,width,height,
1326             exception);
1327           if (p == (const Quantum *) NULL)
1328             {
1329               status=MagickFalse;
1330               break;
1331             }
1332 #if defined(MAGICKCORE_OPENMP_SUPPORT)
1333           #pragma omp parallel for schedule(static,1) shared(progress,status)
1334 #endif
1335           for (y=0; y < (ssize_t) width; y++)
1336           {
1337             register const Quantum
1338               *restrict tile_pixels;
1339
1340             register ssize_t
1341               x;
1342
1343             if (status == MagickFalse)
1344               continue;
1345             q=QueueCacheViewAuthenticPixels(rotate_view,tile_y,(ssize_t) (y+
1346               rotate_image->rows-(tile_x+width)),height,1,exception);
1347             if (q == (Quantum *) NULL)
1348               {
1349                 status=MagickFalse;
1350                 continue;
1351               }
1352             tile_pixels=p+((width-1)-y)*GetPixelChannels(image);
1353             for (x=0; x < (ssize_t) height; x++)
1354             {
1355               register ssize_t
1356                 i;
1357
1358               for (i=0; i < (ssize_t) GetPixelChannels(image); i++)
1359               {
1360                 PixelChannel
1361                   channel;
1362
1363                 PixelTrait
1364                   rotate_traits,
1365                   traits;
1366
1367                 traits=GetPixelChannelMapTraits(image,(PixelChannel) i);
1368                 channel=GetPixelChannelMapChannel(image,(PixelChannel) i);
1369                 rotate_traits=GetPixelChannelMapTraits(rotate_image,channel);
1370                 if ((traits == UndefinedPixelTrait) ||
1371                     (rotate_traits == UndefinedPixelTrait))
1372                   continue;
1373                 if ((rotate_traits & CopyPixelTrait) != 0)
1374                   {
1375                     q[channel]=tile_pixels[i];
1376                     continue;
1377                   }
1378                 q[channel]=tile_pixels[i];
1379               }
1380               tile_pixels+=width*GetPixelChannels(image);
1381               q+=GetPixelChannels(rotate_image);
1382             }
1383             sync=SyncCacheViewAuthenticPixels(rotate_view,exception);
1384             if (sync == MagickFalse)
1385               status=MagickFalse;
1386           }
1387         }
1388         if (image->progress_monitor != (MagickProgressMonitor) NULL)
1389           {
1390             MagickBooleanType
1391               proceed;
1392
1393             proceed=SetImageProgress(image,RotateImageTag,progress+=tile_height,
1394               image->rows);
1395             if (proceed == MagickFalse)
1396               status=MagickFalse;
1397           }
1398       }
1399       (void) SetImageProgress(image,RotateImageTag,(MagickOffsetType)
1400         image->rows-1,image->rows);
1401       Swap(page.width,page.height);
1402       Swap(page.x,page.y);
1403       if (page.height != 0)
1404         page.y=(ssize_t) (page.height-rotate_image->rows-page.y);
1405       break;
1406     }
1407   }
1408   rotate_view=DestroyCacheView(rotate_view);
1409   image_view=DestroyCacheView(image_view);
1410   rotate_image->type=image->type;
1411   rotate_image->page=page;
1412   if (status == MagickFalse)
1413     rotate_image=DestroyImage(rotate_image);
1414   return(rotate_image);
1415 }
1416 \f
1417 /*
1418 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1419 %                                                                             %
1420 %                                                                             %
1421 %                                                                             %
1422 +   X S h e a r I m a g e                                                     %
1423 %                                                                             %
1424 %                                                                             %
1425 %                                                                             %
1426 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1427 %
1428 %  XShearImage() shears the image in the X direction with a shear angle of
1429 %  'degrees'.  Positive angles shear counter-clockwise (right-hand rule), and
1430 %  negative angles shear clockwise.  Angles are measured relative to a vertical
1431 %  Y-axis.  X shears will widen an image creating 'empty' triangles on the left
1432 %  and right sides of the source image.
1433 %
1434 %  The format of the XShearImage method is:
1435 %
1436 %      MagickBooleanType XShearImage(Image *image,const MagickRealType degrees,
1437 %        const size_t width,const size_t height,
1438 %        const ssize_t x_offset,const ssize_t y_offset,ExceptionInfo *exception)
1439 %
1440 %  A description of each parameter follows.
1441 %
1442 %    o image: the image.
1443 %
1444 %    o degrees: A MagickRealType representing the shearing angle along the X
1445 %      axis.
1446 %
1447 %    o width, height, x_offset, y_offset: Defines a region of the image
1448 %      to shear.
1449 %
1450 %    o exception: return any errors or warnings in this structure.
1451 %
1452 */
1453 static MagickBooleanType XShearImage(Image *image,const MagickRealType degrees,
1454   const size_t width,const size_t height,const ssize_t x_offset,
1455   const ssize_t y_offset,ExceptionInfo *exception)
1456 {
1457 #define XShearImageTag  "XShear/Image"
1458
1459   typedef enum
1460   {
1461     LEFT,
1462     RIGHT
1463   } ShearDirection;
1464
1465   CacheView
1466     *image_view;
1467
1468   MagickBooleanType
1469     status;
1470
1471   MagickOffsetType
1472     progress;
1473
1474   PixelInfo
1475     background;
1476
1477   ssize_t
1478     y;
1479
1480   assert(image != (Image *) NULL);
1481   assert(image->signature == MagickSignature);
1482   if (image->debug != MagickFalse)
1483     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
1484   GetPixelInfo(image,&background);
1485   SetPixelInfoPacket(image,&image->background_color,&background);
1486   if (image->colorspace == CMYKColorspace)
1487     ConvertRGBToCMYK(&background);
1488   /*
1489     X shear image.
1490   */
1491   status=MagickTrue;
1492   progress=0;
1493   image_view=AcquireCacheView(image);
1494 #if defined(MAGICKCORE_OPENMP_SUPPORT)
1495   #pragma omp parallel for schedule(dynamic,4) shared(progress, status)
1496 #endif
1497   for (y=0; y < (ssize_t) height; y++)
1498   {
1499     PixelInfo
1500       pixel,
1501       source,
1502       destination;
1503
1504     MagickRealType
1505       area,
1506       displacement;
1507
1508     register Quantum
1509       *restrict p,
1510       *restrict q;
1511
1512     register ssize_t
1513       i;
1514
1515     ShearDirection
1516       direction;
1517
1518     ssize_t
1519       step;
1520
1521     if (status == MagickFalse)
1522       continue;
1523     p=GetCacheViewAuthenticPixels(image_view,0,y_offset+y,image->columns,1,
1524       exception);
1525     if (p == (Quantum *) NULL)
1526       {
1527         status=MagickFalse;
1528         continue;
1529       }
1530     p+=x_offset*GetPixelChannels(image);
1531     displacement=degrees*(MagickRealType) (y-height/2.0);
1532     if (displacement == 0.0)
1533       continue;
1534     if (displacement > 0.0)
1535       direction=RIGHT;
1536     else
1537       {
1538         displacement*=(-1.0);
1539         direction=LEFT;
1540       }
1541     step=(ssize_t) floor((double) displacement);
1542     area=(MagickRealType) (displacement-step);
1543     step++;
1544     pixel=background;
1545     GetPixelInfo(image,&source);
1546     GetPixelInfo(image,&destination);
1547     switch (direction)
1548     {
1549       case LEFT:
1550       {
1551         /*
1552           Transfer pixels left-to-right.
1553         */
1554         if (step > x_offset)
1555           break;
1556         q=p-step*GetPixelChannels(image);
1557         for (i=0; i < (ssize_t) width; i++)
1558         {
1559           if ((x_offset+i) < step)
1560             {
1561               p+=GetPixelChannels(image);
1562               SetPixelInfo(image,p,&pixel);
1563               q+=GetPixelChannels(image);
1564               continue;
1565             }
1566           SetPixelInfo(image,p,&source);
1567           CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1568             &source,(MagickRealType) GetPixelAlpha(image,p),area,
1569             &destination);
1570           SetPixelPixelInfo(image,&destination,q);
1571           SetPixelInfo(image,p,&pixel);
1572           p+=GetPixelChannels(image);
1573           q+=GetPixelChannels(image);
1574         }
1575         CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1576           &background,(MagickRealType) background.alpha,area,&destination);
1577         SetPixelPixelInfo(image,&destination,q);
1578         q+=GetPixelChannels(image);
1579         for (i=0; i < (step-1); i++)
1580         {
1581           SetPixelPixelInfo(image,&background,q);
1582           q+=GetPixelChannels(image);
1583         }
1584         break;
1585       }
1586       case RIGHT:
1587       {
1588         /*
1589           Transfer pixels right-to-left.
1590         */
1591         p+=width*GetPixelChannels(image);
1592         q=p+step*GetPixelChannels(image);
1593         for (i=0; i < (ssize_t) width; i++)
1594         {
1595           p-=GetPixelChannels(image);
1596           q-=GetPixelChannels(image);
1597           if ((size_t) (x_offset+width+step-i) >= image->columns)
1598             continue;
1599           SetPixelInfo(image,p,&source);
1600           CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1601             &source,(MagickRealType) GetPixelAlpha(image,p),area,
1602             &destination);
1603           SetPixelPixelInfo(image,&destination,q);
1604           SetPixelInfo(image,p,&pixel);
1605         }
1606         CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1607           &background,(MagickRealType) background.alpha,area,&destination);
1608         q-=GetPixelChannels(image);
1609         SetPixelPixelInfo(image,&destination,q);
1610         for (i=0; i < (step-1); i++)
1611         {
1612           q-=GetPixelChannels(image);
1613           SetPixelPixelInfo(image,&background,q);
1614         }
1615         break;
1616       }
1617     }
1618     if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
1619       status=MagickFalse;
1620     if (image->progress_monitor != (MagickProgressMonitor) NULL)
1621       {
1622         MagickBooleanType
1623           proceed;
1624
1625 #if defined(MAGICKCORE_OPENMP_SUPPORT)
1626   #pragma omp critical (MagickCore_XShearImage)
1627 #endif
1628         proceed=SetImageProgress(image,XShearImageTag,progress++,height);
1629         if (proceed == MagickFalse)
1630           status=MagickFalse;
1631       }
1632   }
1633   image_view=DestroyCacheView(image_view);
1634   return(status);
1635 }
1636 \f
1637 /*
1638 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1639 %                                                                             %
1640 %                                                                             %
1641 %                                                                             %
1642 +   Y S h e a r I m a g e                                                     %
1643 %                                                                             %
1644 %                                                                             %
1645 %                                                                             %
1646 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1647 %
1648 %  YShearImage shears the image in the Y direction with a shear angle of
1649 %  'degrees'.  Positive angles shear counter-clockwise (right-hand rule), and
1650 %  negative angles shear clockwise.  Angles are measured relative to a
1651 %  horizontal X-axis.  Y shears will increase the height of an image creating
1652 %  'empty' triangles on the top and bottom of the source image.
1653 %
1654 %  The format of the YShearImage method is:
1655 %
1656 %      MagickBooleanType YShearImage(Image *image,const MagickRealType degrees,
1657 %        const size_t width,const size_t height,
1658 %        const ssize_t x_offset,const ssize_t y_offset,ExceptionInfo *exception)
1659 %
1660 %  A description of each parameter follows.
1661 %
1662 %    o image: the image.
1663 %
1664 %    o degrees: A MagickRealType representing the shearing angle along the Y
1665 %      axis.
1666 %
1667 %    o width, height, x_offset, y_offset: Defines a region of the image
1668 %      to shear.
1669 %
1670 %    o exception: return any errors or warnings in this structure.
1671 %
1672 */
1673 static MagickBooleanType YShearImage(Image *image,const MagickRealType degrees,
1674   const size_t width,const size_t height,const ssize_t x_offset,
1675   const ssize_t y_offset,ExceptionInfo *exception)
1676 {
1677 #define YShearImageTag  "YShear/Image"
1678
1679   typedef enum
1680   {
1681     UP,
1682     DOWN
1683   } ShearDirection;
1684
1685   CacheView
1686     *image_view;
1687
1688   MagickBooleanType
1689     status;
1690
1691   MagickOffsetType
1692     progress;
1693
1694   PixelInfo
1695     background;
1696
1697   ssize_t
1698     x;
1699
1700   assert(image != (Image *) NULL);
1701   assert(image->signature == MagickSignature);
1702   if (image->debug != MagickFalse)
1703     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
1704   GetPixelInfo(image,&background);
1705   SetPixelInfoPacket(image,&image->background_color,&background);
1706   if (image->colorspace == CMYKColorspace)
1707     ConvertRGBToCMYK(&background);
1708   /*
1709     Y Shear image.
1710   */
1711   status=MagickTrue;
1712   progress=0;
1713   image_view=AcquireCacheView(image);
1714 #if defined(MAGICKCORE_OPENMP_SUPPORT)
1715   #pragma omp parallel for schedule(dynamic,4) shared(progress, status)
1716 #endif
1717   for (x=0; x < (ssize_t) width; x++)
1718   {
1719     ssize_t
1720       step;
1721
1722     MagickRealType
1723       area,
1724       displacement;
1725
1726     PixelInfo
1727       pixel,
1728       source,
1729       destination;
1730
1731     register Quantum
1732       *restrict p,
1733       *restrict q;
1734
1735     register ssize_t
1736       i;
1737
1738     ShearDirection
1739       direction;
1740
1741     if (status == MagickFalse)
1742       continue;
1743     p=GetCacheViewAuthenticPixels(image_view,x_offset+x,0,1,image->rows,
1744       exception);
1745     if (p == (Quantum *) NULL)
1746       {
1747         status=MagickFalse;
1748         continue;
1749       }
1750     p+=y_offset*GetPixelChannels(image);
1751     displacement=degrees*(MagickRealType) (x-width/2.0);
1752     if (displacement == 0.0)
1753       continue;
1754     if (displacement > 0.0)
1755       direction=DOWN;
1756     else
1757       {
1758         displacement*=(-1.0);
1759         direction=UP;
1760       }
1761     step=(ssize_t) floor((double) displacement);
1762     area=(MagickRealType) (displacement-step);
1763     step++;
1764     pixel=background;
1765     GetPixelInfo(image,&source);
1766     GetPixelInfo(image,&destination);
1767     switch (direction)
1768     {
1769       case UP:
1770       {
1771         /*
1772           Transfer pixels top-to-bottom.
1773         */
1774         if (step > y_offset)
1775           break;
1776         q=p-step*GetPixelChannels(image);
1777         for (i=0; i < (ssize_t) height; i++)
1778         {
1779           if ((y_offset+i) < step)
1780             {
1781               p+=GetPixelChannels(image);
1782               SetPixelInfo(image,p,&pixel);
1783               q+=GetPixelChannels(image);
1784               continue;
1785             }
1786           SetPixelInfo(image,p,&source);
1787           CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1788             &source,(MagickRealType) GetPixelAlpha(image,p),area,
1789             &destination);
1790           SetPixelPixelInfo(image,&destination,q);
1791           SetPixelInfo(image,p,&pixel);
1792           p+=GetPixelChannels(image);
1793           q+=GetPixelChannels(image);
1794         }
1795         CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1796           &background,(MagickRealType) background.alpha,area,&destination);
1797         SetPixelPixelInfo(image,&destination,q);
1798         q+=GetPixelChannels(image);
1799         for (i=0; i < (step-1); i++)
1800         {
1801           SetPixelPixelInfo(image,&background,q);
1802           q+=GetPixelChannels(image);
1803         }
1804         break;
1805       }
1806       case DOWN:
1807       {
1808         /*
1809           Transfer pixels bottom-to-top.
1810         */
1811         p+=height*GetPixelChannels(image);
1812         q=p+step*GetPixelChannels(image);
1813         for (i=0; i < (ssize_t) height; i++)
1814         {
1815           p-=GetPixelChannels(image);
1816           q-=GetPixelChannels(image);
1817           if ((size_t) (y_offset+height+step-i) >= image->rows)
1818             continue;
1819           SetPixelInfo(image,p,&source);
1820           CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1821             &source,(MagickRealType) GetPixelAlpha(image,p),area,
1822             &destination);
1823           SetPixelPixelInfo(image,&destination,q);
1824           SetPixelInfo(image,p,&pixel);
1825         }
1826         CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1827           &background,(MagickRealType) background.alpha,area,&destination);
1828         q-=GetPixelChannels(image);
1829         SetPixelPixelInfo(image,&destination,q);
1830         for (i=0; i < (step-1); i++)
1831         {
1832           q-=GetPixelChannels(image);
1833           SetPixelPixelInfo(image,&background,q);
1834         }
1835         break;
1836       }
1837     }
1838     if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
1839       status=MagickFalse;
1840     if (image->progress_monitor != (MagickProgressMonitor) NULL)
1841       {
1842         MagickBooleanType
1843           proceed;
1844
1845 #if defined(MAGICKCORE_OPENMP_SUPPORT)
1846   #pragma omp critical (MagickCore_YShearImage)
1847 #endif
1848         proceed=SetImageProgress(image,YShearImageTag,progress++,image->rows);
1849         if (proceed == MagickFalse)
1850           status=MagickFalse;
1851       }
1852   }
1853   image_view=DestroyCacheView(image_view);
1854   return(status);
1855 }
1856 \f
1857 /*
1858 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1859 %                                                                             %
1860 %                                                                             %
1861 %                                                                             %
1862 %   R o t a t e I m a g e                                                     %
1863 %                                                                             %
1864 %                                                                             %
1865 %                                                                             %
1866 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1867 %
1868 %  RotateImage() creates a new image that is a rotated copy of an existing
1869 %  one.  Positive angles rotate counter-clockwise (right-hand rule), while
1870 %  negative angles rotate clockwise.  Rotated images are usually larger than
1871 %  the originals and have 'empty' triangular corners.  X axis.  Empty
1872 %  triangles left over from shearing the image are filled with the background
1873 %  color defined by member 'background_color' of the image.  RotateImage
1874 %  allocates the memory necessary for the new Image structure and returns a
1875 %  pointer to the new image.
1876 %
1877 %  RotateImage() is based on the paper "A Fast Algorithm for General
1878 %  Raster Rotatation" by Alan W. Paeth.  RotateImage is adapted from a similar
1879 %  method based on the Paeth paper written by Michael Halle of the Spatial
1880 %  Imaging Group, MIT Media Lab.
1881 %
1882 %  The format of the RotateImage method is:
1883 %
1884 %      Image *RotateImage(const Image *image,const double degrees,
1885 %        ExceptionInfo *exception)
1886 %
1887 %  A description of each parameter follows.
1888 %
1889 %    o image: the image.
1890 %
1891 %    o degrees: Specifies the number of degrees to rotate the image.
1892 %
1893 %    o exception: return any errors or warnings in this structure.
1894 %
1895 */
1896 MagickExport Image *RotateImage(const Image *image,const double degrees,
1897   ExceptionInfo *exception)
1898 {
1899   Image
1900     *integral_image,
1901     *rotate_image;
1902
1903   MagickBooleanType
1904     status;
1905
1906   MagickRealType
1907     angle;
1908
1909   PointInfo
1910     shear;
1911
1912   RectangleInfo
1913     border_info;
1914
1915   size_t
1916     height,
1917     rotations,
1918     width,
1919     y_width;
1920
1921   ssize_t
1922     x_offset,
1923     y_offset;
1924
1925   /*
1926     Adjust rotation angle.
1927   */
1928   assert(image != (Image *) NULL);
1929   assert(image->signature == MagickSignature);
1930   if (image->debug != MagickFalse)
1931     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
1932   assert(exception != (ExceptionInfo *) NULL);
1933   assert(exception->signature == MagickSignature);
1934   angle=degrees;
1935   while (angle < -45.0)
1936     angle+=360.0;
1937   for (rotations=0; angle > 45.0; rotations++)
1938     angle-=90.0;
1939   rotations%=4;
1940   /*
1941     Calculate shear equations.
1942   */
1943   integral_image=IntegralRotateImage(image,rotations,exception);
1944   if (integral_image == (Image *) NULL)
1945     ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
1946   shear.x=(-tan((double) DegreesToRadians(angle)/2.0));
1947   shear.y=sin((double) DegreesToRadians(angle));
1948   if ((shear.x == 0.0) && (shear.y == 0.0))
1949     return(integral_image);
1950   if (SetImageStorageClass(integral_image,DirectClass,exception) == MagickFalse)
1951     {
1952       integral_image=DestroyImage(integral_image);
1953       return(integral_image);
1954     }
1955   if (integral_image->matte == MagickFalse)
1956     (void) SetImageAlphaChannel(integral_image,OpaqueAlphaChannel,exception);
1957   /*
1958     Compute image size.
1959   */
1960   width=image->columns;
1961   height=image->rows;
1962   if ((rotations == 1) || (rotations == 3))
1963     {
1964       width=image->rows;
1965       height=image->columns;
1966     }
1967   y_width=width+(ssize_t) floor(fabs(shear.x)*height+0.5);
1968   x_offset=(ssize_t) ceil((double) width+((fabs(shear.y)*height)-width)/2.0-
1969     0.5);
1970   y_offset=(ssize_t) ceil((double) height+((fabs(shear.y)*y_width)-height)/2.0-
1971     0.5);
1972   /*
1973     Surround image with a border.
1974   */
1975   integral_image->border_color=integral_image->background_color;
1976   integral_image->compose=CopyCompositeOp;
1977   border_info.width=(size_t) x_offset;
1978   border_info.height=(size_t) y_offset;
1979   rotate_image=BorderImage(integral_image,&border_info,image->compose,
1980     exception);
1981   integral_image=DestroyImage(integral_image);
1982   if (rotate_image == (Image *) NULL)
1983     ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
1984   /*
1985     Rotate the image.
1986   */
1987   status=XShearImage(rotate_image,shear.x,width,height,x_offset,(ssize_t)
1988     (rotate_image->rows-height)/2,exception);
1989   if (status == MagickFalse)
1990     {
1991       rotate_image=DestroyImage(rotate_image);
1992       return((Image *) NULL);
1993     }
1994   status=YShearImage(rotate_image,shear.y,y_width,height,(ssize_t)
1995     (rotate_image->columns-y_width)/2,y_offset,exception);
1996   if (status == MagickFalse)
1997     {
1998       rotate_image=DestroyImage(rotate_image);
1999       return((Image *) NULL);
2000     }
2001   status=XShearImage(rotate_image,shear.x,y_width,rotate_image->rows,(ssize_t)
2002     (rotate_image->columns-y_width)/2,0,exception);
2003   if (status == MagickFalse)
2004     {
2005       rotate_image=DestroyImage(rotate_image);
2006       return((Image *) NULL);
2007     }
2008   status=CropToFitImage(&rotate_image,shear.x,shear.y,(MagickRealType) width,
2009     (MagickRealType) height,MagickTrue,exception);
2010   if (status == MagickFalse)
2011     {
2012       rotate_image=DestroyImage(rotate_image);
2013       return((Image *) NULL);
2014     }
2015   rotate_image->compose=image->compose;
2016   rotate_image->page.width=0;
2017   rotate_image->page.height=0;
2018   return(rotate_image);
2019 }
2020 \f
2021 /*
2022 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2023 %                                                                             %
2024 %                                                                             %
2025 %                                                                             %
2026 %   S h e a r I m a g e                                                       %
2027 %                                                                             %
2028 %                                                                             %
2029 %                                                                             %
2030 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2031 %
2032 %  ShearImage() creates a new image that is a shear_image copy of an existing
2033 %  one.  Shearing slides one edge of an image along the X or Y axis, creating
2034 %  a parallelogram.  An X direction shear slides an edge along the X axis,
2035 %  while a Y direction shear slides an edge along the Y axis.  The amount of
2036 %  the shear is controlled by a shear angle.  For X direction shears, x_shear
2037 %  is measured relative to the Y axis, and similarly, for Y direction shears
2038 %  y_shear is measured relative to the X axis.  Empty triangles left over from
2039 %  shearing the image are filled with the background color defined by member
2040 %  'background_color' of the image..  ShearImage() allocates the memory
2041 %  necessary for the new Image structure and returns a pointer to the new image.
2042 %
2043 %  ShearImage() is based on the paper "A Fast Algorithm for General Raster
2044 %  Rotatation" by Alan W. Paeth.
2045 %
2046 %  The format of the ShearImage method is:
2047 %
2048 %      Image *ShearImage(const Image *image,const double x_shear,
2049 %        const double y_shear,ExceptionInfo *exception)
2050 %
2051 %  A description of each parameter follows.
2052 %
2053 %    o image: the image.
2054 %
2055 %    o x_shear, y_shear: Specifies the number of degrees to shear the image.
2056 %
2057 %    o exception: return any errors or warnings in this structure.
2058 %
2059 */
2060 MagickExport Image *ShearImage(const Image *image,const double x_shear,
2061   const double y_shear,ExceptionInfo *exception)
2062 {
2063   Image
2064     *integral_image,
2065     *shear_image;
2066
2067   ssize_t
2068     x_offset,
2069     y_offset;
2070
2071   MagickBooleanType
2072     status;
2073
2074   PointInfo
2075     shear;
2076
2077   RectangleInfo
2078     border_info;
2079
2080   size_t
2081     y_width;
2082
2083   assert(image != (Image *) NULL);
2084   assert(image->signature == MagickSignature);
2085   if (image->debug != MagickFalse)
2086     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
2087   assert(exception != (ExceptionInfo *) NULL);
2088   assert(exception->signature == MagickSignature);
2089   if ((x_shear != 0.0) && (fmod(x_shear,90.0) == 0.0))
2090     ThrowImageException(ImageError,"AngleIsDiscontinuous");
2091   if ((y_shear != 0.0) && (fmod(y_shear,90.0) == 0.0))
2092     ThrowImageException(ImageError,"AngleIsDiscontinuous");
2093   /*
2094     Initialize shear angle.
2095   */
2096   integral_image=CloneImage(image,0,0,MagickTrue,exception);
2097   if (integral_image == (Image *) NULL)
2098     ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
2099   shear.x=(-tan(DegreesToRadians(fmod(x_shear,360.0))));
2100   shear.y=tan(DegreesToRadians(fmod(y_shear,360.0)));
2101   if ((shear.x == 0.0) && (shear.y == 0.0))
2102     return(integral_image);
2103   if (SetImageStorageClass(integral_image,DirectClass,exception) == MagickFalse)
2104     {
2105       integral_image=DestroyImage(integral_image);
2106       return(integral_image);
2107     }
2108   if (integral_image->matte == MagickFalse)
2109     (void) SetImageAlphaChannel(integral_image,OpaqueAlphaChannel,exception);
2110   /*
2111     Compute image size.
2112   */
2113   y_width=image->columns+(ssize_t) floor(fabs(shear.x)*image->rows+0.5);
2114   x_offset=(ssize_t) ceil((double) image->columns+((fabs(shear.x)*image->rows)-
2115     image->columns)/2.0-0.5);
2116   y_offset=(ssize_t) ceil((double) image->rows+((fabs(shear.y)*y_width)-
2117     image->rows)/2.0-0.5);
2118   /*
2119     Surround image with border.
2120   */
2121   integral_image->border_color=integral_image->background_color;
2122   integral_image->compose=CopyCompositeOp;
2123   border_info.width=(size_t) x_offset;
2124   border_info.height=(size_t) y_offset;
2125   shear_image=BorderImage(integral_image,&border_info,image->compose,exception);
2126   integral_image=DestroyImage(integral_image);
2127   if (shear_image == (Image *) NULL)
2128     ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
2129   /*
2130     Shear the image.
2131   */
2132   if (shear_image->matte == MagickFalse)
2133     (void) SetImageAlphaChannel(shear_image,OpaqueAlphaChannel,exception);
2134   status=XShearImage(shear_image,shear.x,image->columns,image->rows,x_offset,
2135     (ssize_t) (shear_image->rows-image->rows)/2,exception);
2136   if (status == MagickFalse)
2137     {
2138       shear_image=DestroyImage(shear_image);
2139       return((Image *) NULL);
2140     }
2141   status=YShearImage(shear_image,shear.y,y_width,image->rows,(ssize_t)
2142     (shear_image->columns-y_width)/2,y_offset,exception);
2143   if (status == MagickFalse)
2144     {
2145       shear_image=DestroyImage(shear_image);
2146       return((Image *) NULL);
2147     }
2148   status=CropToFitImage(&shear_image,shear.x,shear.y,(MagickRealType)
2149     image->columns,(MagickRealType) image->rows,MagickFalse,exception);
2150   if (status == MagickFalse)
2151     {
2152       shear_image=DestroyImage(shear_image);
2153       return((Image *) NULL);
2154     }
2155   shear_image->compose=image->compose;
2156   shear_image->page.width=0;
2157   shear_image->page.height=0;
2158   return(shear_image);
2159 }