ass_render: Replace Segment with Rect

Contrary to what the comments suggest Segment does not use one
absolute reference point and relative offsets, but two absolute points,
making it practically identical to the previously defined Rect with
  a <-> y0,  b <-> y1,  ha <-> x0,  hb <-> x1

For simplicity replace Segment with Rect.

2 files changed, 34 insertions, 39 deletions

diff --git a/libass/ass_render.c b/libass/ass_render.c
index bda4147..c0bbb9f 100644
--- a/libass/ass_render.c
+++ b/libass/ass_render.c
@@ -2896,17 +2896,17 @@ static ASS_RenderPriv *get_render_priv(ASS_Renderer *render_priv,
     return event->render_priv;
 }
 
-static int overlap(Segment *s1, Segment *s2)
+static int overlap(Rect *s1, Rect *s2)
 {
-    if (s1->a >= s2->b || s2->a >= s1->b ||
-        s1->ha >= s2->hb || s2->ha >= s1->hb)
+    if (s1->y0 >= s2->y1 || s2->y0 >= s1->y1 ||
+        s1->x0 >= s2->x1 || s2->x0 >= s1->x1)
         return 0;
     return 1;
 }
 
-static int cmp_segment(const void *p1, const void *p2)
+static int cmp_rect_y0(const void *p1, const void *p2)
 {
-    return ((Segment *) p1)->a - ((Segment *) p2)->a;
+    return ((Rect *) p1)->y0 - ((Rect *) p2)->y0;
 }
 
 static void
@@ -2937,31 +2937,31 @@ shift_event(ASS_Renderer *render_priv, EventImages *ei, int shift)
 
 // dir: 1 - move down
 //      -1 - move up
-static int fit_segment(Segment *s, Segment *fixed, int *cnt, int dir)
+static int fit_rect(Rect *s, Rect *fixed, int *cnt, int dir)
 {
     int i;
     int shift = 0;
 
     if (dir == 1)               // move down
         for (i = 0; i < *cnt; ++i) {
-            if (s->b + shift <= fixed[i].a || s->a + shift >= fixed[i].b ||
-                s->hb <= fixed[i].ha || s->ha >= fixed[i].hb)
+            if (s->y1 + shift <= fixed[i].y0 || s->y0 + shift >= fixed[i].y1 ||
+                s->x1 <= fixed[i].x0 || s->x0 >= fixed[i].x1)
                 continue;
-            shift = fixed[i].b - s->a;
+            shift = fixed[i].y1 - s->y0;
     } else                      // dir == -1, move up
         for (i = *cnt - 1; i >= 0; --i) {
-            if (s->b + shift <= fixed[i].a || s->a + shift >= fixed[i].b ||
-                s->hb <= fixed[i].ha || s->ha >= fixed[i].hb)
+            if (s->y1 + shift <= fixed[i].y0 || s->y0 + shift >= fixed[i].y1 ||
+                s->x1 <= fixed[i].x0 || s->x0 >= fixed[i].x1)
                 continue;
-            shift = fixed[i].a - s->b;
+            shift = fixed[i].y0 - s->y1;
         }
 
-    fixed[*cnt].a = s->a + shift;
-    fixed[*cnt].b = s->b + shift;
-    fixed[*cnt].ha = s->ha;
-    fixed[*cnt].hb = s->hb;
+    fixed[*cnt].y0 = s->y0 + shift;
+    fixed[*cnt].y1 = s->y1 + shift;
+    fixed[*cnt].x0 = s->x0;
+    fixed[*cnt].x1 = s->x1;
     (*cnt)++;
-    qsort(fixed, *cnt, sizeof(Segment), cmp_segment);
+    qsort(fixed, *cnt, sizeof(*fixed), cmp_rect_y0);
 
     return shift;
 }
@@ -2969,7 +2969,7 @@ static int fit_segment(Segment *s, Segment *fixed, int *cnt, int dir)
 static void
 fix_collisions(ASS_Renderer *render_priv, EventImages *imgs, int cnt)
 {
-    Segment *used = ass_realloc_array(NULL, cnt, sizeof(*used));
+    Rect *used = ass_realloc_array(NULL, cnt, sizeof(*used));
     int cnt_used = 0;
     int i, j;
 
@@ -2983,11 +2983,11 @@ fix_collisions(ASS_Renderer *render_priv, EventImages *imgs, int cnt)
             continue;
         priv = get_render_priv(render_priv, imgs[i].event);
         if (priv && priv->height > 0) { // it's a fixed event
-            Segment s;
-            s.a = priv->top;
-            s.b = priv->top + priv->height;
-            s.ha = priv->left;
-            s.hb = priv->left + priv->width;
+            Rect s;
+            s.y0 = priv->top;
+            s.y1 = priv->top + priv->height;
+            s.x0 = priv->left;
+            s.x1 = priv->left + priv->width;
             if (priv->height != imgs[i].height) {       // no, it's not
                 ass_msg(render_priv->library, MSGL_WARN,
                         "Event height has changed");
@@ -3004,16 +3004,16 @@ fix_collisions(ASS_Renderer *render_priv, EventImages *imgs, int cnt)
                     priv->width = 0;
                 }
             if (priv->height > 0) {     // still a fixed event
-                used[cnt_used].a = priv->top;
-                used[cnt_used].b = priv->top + priv->height;
-                used[cnt_used].ha = priv->left;
-                used[cnt_used].hb = priv->left + priv->width;
+                used[cnt_used].y0 = priv->top;
+                used[cnt_used].y1 = priv->top + priv->height;
+                used[cnt_used].x0 = priv->left;
+                used[cnt_used].x1 = priv->left + priv->width;
                 cnt_used++;
                 shift_event(render_priv, imgs + i, priv->top - imgs[i].top);
             }
         }
     }
-    qsort(used, cnt_used, sizeof(Segment), cmp_segment);
+    qsort(used, cnt_used, sizeof(*used), cmp_rect_y0);
 
     // try to fit other events in free spaces
     for (i = 0; i < cnt; ++i) {
@@ -3023,12 +3023,12 @@ fix_collisions(ASS_Renderer *render_priv, EventImages *imgs, int cnt)
         priv = get_render_priv(render_priv, imgs[i].event);
         if (priv && priv->height == 0) {        // not a fixed event
             int shift;
-            Segment s;
-            s.a = imgs[i].top;
-            s.b = imgs[i].top + imgs[i].height;
-            s.ha = imgs[i].left;
-            s.hb = imgs[i].left + imgs[i].width;
-            shift = fit_segment(&s, used, &cnt_used, imgs[i].shift_direction);
+            Rect s;
+            s.y0 = imgs[i].top;
+            s.y1 = imgs[i].top + imgs[i].height;
+            s.x0 = imgs[i].left;
+            s.x1 = imgs[i].left + imgs[i].width;
+            shift = fit_rect(&s, used, &cnt_used, imgs[i].shift_direction);
             if (shift)
                 shift_event(render_priv, imgs + i, shift);
             // make it fixed
diff --git a/libass/ass_render.h b/libass/ass_render.h
index 359152a..5208f04 100644
--- a/libass/ass_render.h
+++ b/libass/ass_render.h
@@ -334,11 +334,6 @@ typedef struct {
     int y1;
 } Rect;
 
-typedef struct {
-    int a, b;                   // top and height
-    int ha, hb;                 // left and width
-} Segment;
-
 void reset_render_context(ASS_Renderer *render_priv, ASS_Style *style);
 void ass_frame_ref(ASS_Image *img);
 void ass_frame_unref(ASS_Image *img);