Fix change detection when text is clipped to screen

The glyphs are clipped before combining, so the combined bitmap can
always have the same position, size, and address. This breaks the
change detection. Or at least I think that's what happens.

diff --git a/libass/ass_render.c b/libass/ass_render.c
index 85c6aec0277392662e53b04a8d93a7beab898f03..8e590e839421d5c3a6eac955e34a74c26a7fdeb7 100644 (file)
--- a/libass/ass_render.c
+++ b/libass/ass_render.c
@@ -449,18 +449,22 @@ render_glyph(ASS_Renderer *render_priv, Bitmap *bm, int dst_x, int dst_y,
     tmp = dst_x - clip_x0;
     if (tmp < 0) {
         b_x0 = -tmp;
+        render_priv->state.has_clips = 1;
     }
     tmp = dst_y - clip_y0;
     if (tmp < 0) {
         b_y0 = -tmp;
+        render_priv->state.has_clips = 1;
     }
     tmp = clip_x1 - dst_x - bm->w;
     if (tmp < 0) {
         b_x1 = bm->w + tmp;
+        render_priv->state.has_clips = 1;
     }
     tmp = clip_y1 - dst_y - bm->h;
     if (tmp < 0) {
         b_y1 = bm->h + tmp;
+        render_priv->state.has_clips = 1;
     }
 
     if ((b_y0 >= b_y1) || (b_x0 >= b_x1))
@@ -571,7 +575,7 @@ static void blend_vector_clip(ASS_Renderer *render_priv,
         int aleft, atop, bleft, btop;
         unsigned char *abuffer, *bbuffer, *nbuffer;
 
-        render_priv->state.has_vector_clip = 1;
+        render_priv->state.has_clips = 1;
 
         abuffer = cur->bitmap;
         bbuffer = clip_bm->buffer;
@@ -810,7 +814,7 @@ init_render_context(ASS_Renderer *render_priv, ASS_Event *event)
     render_priv->state.event = event;
     render_priv->state.style = render_priv->track->styles + event->Style;
     render_priv->state.parsed_tags = 0;
-    render_priv->state.has_vector_clip = 0;
+    render_priv->state.has_clips = 0;
 
     reset_render_context(render_priv, render_priv->state.style);
     render_priv->state.wrap_style = render_priv->track->WrapStyle;
@@ -2856,7 +2860,7 @@ static int ass_detect_change(ASS_Renderer *priv)
     ASS_Image *img, *img2;
     int diff;
 
-    if (priv->cache_cleared || priv->state.has_vector_clip)
+    if (priv->cache_cleared || priv->state.has_clips)
         return 2;
 
     img = priv->prev_images_root;

diff --git a/libass/ass_render.h b/libass/ass_render.h
index 2cb2210c71a29410e75df967fc7541c6f807eed4..8e15ad5df2654b04d1f6d817efd33ddd57eca728 100644 (file)
--- a/libass/ass_render.h
+++ b/libass/ass_render.h
@@ -232,7 +232,7 @@ typedef struct {
     ASS_Event *event;
     ASS_Style *style;
     int parsed_tags;
-    int has_vector_clip;
+    int has_clips;              // clips that conflict with cache change detection
 
     ASS_Font *font;
     double font_size;