Re: [AD] Patch for rotate.c

[Sven Sandberg <svens@xxxxxxxxxx>]

Evert Glebbeek wrote:
> In other words, the patch is correct and should be applied, although the 
> stray pixels appearing isn't the proper reason for doing so?
> Just to be sure :)

Sorry if I was unclear. What I meant was, the patch does what it was 
intended to do, namely forgives the user for doing wrong (i.e., it 
avoids ugly pixels when the user tries to draw outside the bitmap with 
clipping turned off). I then questioned whether we should be that "nice" 
to users. I think it would be good to also add an ASSERT that fails when 
users try to draw outside the BITMAP with clipping turned off, so that 
they can fix their programs. I attach a patch that does this. OK?

/Sven

Index: src/rotate.c
===================================================================
RCS file: /cvsroot/alleg/allegro/src/rotate.c,v
retrieving revision 1.18
diff -u -r1.18 rotate.c
--- src/rotate.c	14 Dec 2003 18:57:07 -0000	1.18
+++ src/rotate.c	30 Oct 2004 10:15:25 -0000
@@ -317,8 +317,12 @@
       clip_right = (bmp->cr << 16) - 1;
    }
    else {
+      ASSERT(left_bmp_x >= 0 && top_bmp_x >= 0 && bottom_bmp_x >= 0
+	     && right_bmp_x < (bmp->w << 16)
+	     && top_bmp_x < (bmp->w << 16)
+	     && bottom_bmp_x < (bmp->w << 16));
       clip_left = 0;
-      clip_right = bmp->w << 16;
+      clip_right = (bmp->w << 16) - 1;
    }
 
    /* Quit if we're totally outside. */
@@ -336,18 +340,24 @@
       clip_bottom_i = (bottom_bmp_y + 0xffff) >> 16;
    else
       clip_bottom_i = (bottom_bmp_y + 0x8000) >> 16;
-   if (bmp->clip)
+   if (bmp->clip) {
       if (clip_bottom_i > bmp->cb)
 	 clip_bottom_i = bmp->cb;
+   }
+   else
+      ASSERT(clip_bottom_i <= bmp->h);
 
    /* Calculate y coordinate of first scanline. */
    if (sub_pixel_accuracy)
       bmp_y_i = top_bmp_y >> 16;
    else
       bmp_y_i = (top_bmp_y + 0x8000) >> 16;
-   if (bmp->clip)
+   if (bmp->clip) {
       if (bmp_y_i < bmp->ct)
 	 bmp_y_i = bmp->ct;
+   }
+   else
+      ASSERT(bmp_y_i >= 0);
 
    /* Sprite is above or below bottom clipping area. */
    if (bmp_y_i >= clip_bottom_i)