fix panning at zoomed scales

diff --git a/lib/gvc/gvemit.c b/lib/gvc/gvemit.c
index 10f9e50eca7f69ee8942c30f8e4223c8855ec33a..23a70e5bfdedec1d92c6b1e81280c0f6f6c41e60 100644 (file)
--- a/lib/gvc/gvemit.c
+++ b/lib/gvc/gvemit.c
@@ -304,16 +304,20 @@ static void win_handle_button_press(win_t *win, XButtonEvent *bev)
     case 4:
        /* scrollwheel zoom in at current mouse x,y */
        win->fit_mode = 0;
-       win->gvc->focus.x +=  (bev->x - win->gvc->width / 2.) * win->gvc->zoom * (ZOOMFACTOR - 1.);
-       win->gvc->focus.y += -(bev->y - win->gvc->height / 2.) * win->gvc->zoom * (ZOOMFACTOR - 1.);
+       win->gvc->focus.x +=  (bev->x - win->gvc->width / 2.)
+               * (ZOOMFACTOR - 1.) / win->gvc->zoom;
+       win->gvc->focus.y += -(bev->y - win->gvc->height / 2.)
+               * (ZOOMFACTOR - 1.) / win->gvc->zoom;
        win->gvc->zoom *= ZOOMFACTOR;
        win->needs_refresh = 1;
        break;
     case 5: /* scrollwheel zoom out at current mouse x,y */
        win->fit_mode = 0;
        win->gvc->zoom /= ZOOMFACTOR;
-       win->gvc->focus.x -=  (bev->x - win->gvc->width / 2.) * win->gvc->zoom * (ZOOMFACTOR - 1.);
-       win->gvc->focus.y -= -(bev->y - win->gvc->height / 2.) * win->gvc->zoom * (ZOOMFACTOR - 1.);
+       win->gvc->focus.x -=  (bev->x - win->gvc->width / 2.)
+               * (ZOOMFACTOR - 1.) / win->gvc->zoom;
+       win->gvc->focus.y -= -(bev->y - win->gvc->height / 2.)
+               * (ZOOMFACTOR - 1.) / win->gvc->zoom;
        win->needs_refresh = 1;
        break;
     }
@@ -331,8 +335,8 @@ static void win_handle_motion(win_t *win, XMotionEvent *mev)
        /* FIXME - to be implemented */
        break;
     case 2: /* drag with button 2 - pan graph */
-       win->gvc->focus.x -=  (mev->x - win->oldx) * win->gvc->zoom;
-       win->gvc->focus.y -= -(mev->y - win->oldy) * win->gvc->zoom;
+       win->gvc->focus.x -=  (mev->x - win->oldx) / win->gvc->zoom;
+       win->gvc->focus.y -= -(mev->y - win->oldy) / win->gvc->zoom;
        win->needs_refresh = 1;
        break;
     case 3: /* drag with button 3 - unused */
@@ -463,7 +467,7 @@ static int quit_cb(win_t * win)
 static int left_cb(win_t * win)
 {
     win->fit_mode = 0;
-    win->gvc->focus.x += PANFACTOR * win->gvc->zoom;
+    win->gvc->focus.x += PANFACTOR / win->gvc->zoom;
     win->needs_refresh = 1;
     return 0;
 }
@@ -471,7 +475,7 @@ static int left_cb(win_t * win)
 static int right_cb(win_t * win)
 {
     win->fit_mode = 0;
-    win->gvc->focus.x -= PANFACTOR * win->gvc->zoom;
+    win->gvc->focus.x -= PANFACTOR / win->gvc->zoom;
     win->needs_refresh = 1;
     return 0;
 }
@@ -479,7 +483,7 @@ static int right_cb(win_t * win)
 static int up_cb(win_t * win)
 {
     win->fit_mode = 0;
-    win->gvc->focus.y += -(PANFACTOR * win->gvc->zoom);
+    win->gvc->focus.y += -(PANFACTOR / win->gvc->zoom);
     win->needs_refresh = 1;
     return 0;
 }
@@ -487,7 +491,7 @@ static int up_cb(win_t * win)
 static int down_cb(win_t * win)
 {
     win->fit_mode = 0;
-    win->gvc->focus.y -= -(PANFACTOR * win->gvc->zoom);
+    win->gvc->focus.y -= -(PANFACTOR / win->gvc->zoom);
     win->needs_refresh = 1;
     return 0;
 }