SF.net SVN: alleg:[11858] allegro/branches/4.9/src/memblit.c

[<tj...@us...>]

Revision: 11858
          http://alleg.svn.sourceforge.net/alleg/?rev=11858&view=rev
Author:   tjaden
Date:     2009-03-15 06:19:06 +0000 (Sun, 15 Mar 2009)

Log Message:
-----------
Fix clipping of software blitting routines, again.

- They did not clip properly when the destination width/height was negative,
leading to out-of-bounds memory access.

- They did not draw right up to the edges of the clipping rectangle
(off by one row or column).

- There was an off-by-one bug in _al_draw_bitmap_region_memory_fast().

Modified Paths:
--------------
    allegro/branches/4.9/src/memblit.c

Modified: allegro/branches/4.9/src/memblit.c
===================================================================
--- allegro/branches/4.9/src/memblit.c	2009-03-15 06:18:22 UTC (rev 11857)
+++ allegro/branches/4.9/src/memblit.c	2009-03-15 06:19:06 UTC (rev 11858)
@@ -269,12 +269,14 @@
    sxinc = fabs((float)sw / dw);
    syinc = fabs((float)sh / dh);
 
-   /* Do clipping */
+   /* Do clipping.  We subtract 1 from ct and cl as they are inclusive,
+    * but dw, dh are exclusive.
+    */
    dy = ((dy > dest->ct) ? dy : dest->ct);
-   dh = (((dy + dh) < dest->cb + 1) ? (dy + dh) : dest->cb + 1) - dy;
+   dh = _ALLEGRO_CLAMP(dest->ct - 1, dy + dh, dest->cb) - dy;
 
    dx = ((dx > dest->cl) ? dx : dest->cl);
-   dw = (((dx + dw) < dest->cr + 1) ? (dx + dw) : dest->cr + 1) - dx;
+   dw = _ALLEGRO_CLAMP(dest->cl - 1, dx + dw, dest->cr) - dx;
 
    if (dw == 0 || dh == 0)
       return;
@@ -303,7 +305,6 @@
 
    dxinc = dw < 0 ? -1 : 1;
    dyinc = dh < 0 ? -1 : 1;
-   _dy = dy;
    xend = abs(dw);
    yend = abs(dh);
 
@@ -321,6 +322,7 @@
    }
 
    /* XXX optimise this */
+   _dy = dy;
    for (y = 0; y < yend; y++) {
       _sx = sx;
       _dx = dx;
@@ -482,7 +484,7 @@
                                                                              \
    /* Calculate left and right clipping. */                                  \
    clip_left = dst->cl << 16;                                                \
-   clip_right = (dst->cr << 16) - 1;                                         \
+   clip_right = dst->cr << 16;                                               \
                                                                              \
    /* Quit if we're totally outside. */                                      \
    if ((left_bmp_x > clip_right) &&                                          \
@@ -904,8 +906,8 @@
       dx = dest->cl;
       sw -= inc;
    }
-   if (dx+sw-1 > dest->cr) {
-      int inc = (dx+sw-1) - dest->cr;
+   if (dx+sw > dest->cr) {
+      int inc = (dx+sw) - dest->cr;
       sw -= inc;
    }
 
@@ -915,8 +917,8 @@
       dy = dest->ct;
       sh -= inc;
    }
-   if (dy+sh-1 > dest->cb) {
-      int inc = (dy+sh-1) - dest->cb;
+   if (dy+sh > dest->cb) {
+      int inc = (dy+sh) - dest->cb;
       sh -= inc;
    }
 
@@ -1020,12 +1022,14 @@
    sxinc = fabs((float)sw / dw);
    syinc = fabs((float)sh / dh);
 
-   /* Do clipping */
+   /* Do clipping.  We subtract 1 from ct and cl as they are inclusive,
+    * but dw, dh are exclusive.
+    */
    dy = ((dy > dest->ct) ? dy : dest->ct);
-   dh = (((dy + dh) < dest->cb + 1) ? (dy + dh) : dest->cb + 1) - dy;
+   dh = _ALLEGRO_CLAMP(dest->ct - 1, dy + dh, dest->cb) - dy;
 
    dx = ((dx > dest->cl) ? dx : dest->cl);
-   dw = (((dx + dw) < dest->cr + 1) ? (dx + dw) : dest->cr + 1) - dx;
+   dw = _ALLEGRO_CLAMP(dest->cl - 1, dx + dw, dest->cr) - dx;
 
    if (dw == 0 || dh == 0)
       return;
@@ -1043,7 +1047,8 @@
       src = src->parent;
    }
 
-   if (!(src_region = al_lock_bitmap(src, ALLEGRO_PIXEL_FORMAT_ARGB_8888, ALLEGRO_LOCK_READONLY))) {
+   if (!(src_region = al_lock_bitmap(src, ALLEGRO_PIXEL_FORMAT_ARGB_8888,
+         ALLEGRO_LOCK_READONLY))) {
       return;
    }
    /* XXX we should be able to lock less of the destination and use
@@ -1056,7 +1061,6 @@
 
    dxinc = dw < 0 ? -1 : 1;
    dyinc = dh < 0 ? -1 : 1;
-   _dy = dy;
    xend = abs(dw);
    yend = abs(dh);
 
@@ -1073,6 +1077,7 @@
       _sy = sy;
    }
 
+   _dy = dy;
    for (y = 0; y < yend; y++) {
       _sx = sx;
       _dx = dx;
@@ -1252,7 +1257,7 @@
 
    /* Calculate left and right clipping. */
    clip_left = dst->cl << 16;
-   clip_right = (dst->cr << 16) - 1;
+   clip_right = dst->cr << 16;
 
    /* Quit if we're totally outside. */
    if ((left_bmp_x > clip_right) &&


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