[cairo] [PATCH] fix _cairo_rectangle_intersect
Jeff Muizelaar
jrmuizel at nit.ca
Wed Feb 23 11:46:39 PST 2005
_cairo_rectangle_intersect gives bad results whenever
MIN (dest->x + dest->width, src->x + src->width) - out.x
is negative because of assignment to an unsigned short.
The appended patch fixes the problem by using variables of type int for
the computation results.
There are still problems when x + width is > 655536, but at
least that is a lot more rare. Are there any reasons width and height
are unsigned to begin with?
2005-02-23 Jeff Muizelaar <jrmuizel at nit.ca>
* src/cairo_gstate.c (_cairo_rectangle_intersect)
make the computation correct when the intersection
negative width
Index: src/cairo_gstate.c
===================================================================
RCS file: /cvs/cairo/cairo/src/cairo_gstate.c,v
retrieving revision 1.84
diff -u -r1.84 cairo_gstate.c
--- src/cairo_gstate.c 22 Feb 2005 19:35:03 -0000 1.84
+++ src/cairo_gstate.c 23 Feb 2005 19:13:02 -0000
@@ -1414,18 +1414,21 @@
_cairo_rectangle_intersect (cairo_rectangle_t *dest, cairo_rectangle_t *src)
{
cairo_rectangle_t out;
+ int width, height;
out.x = MAX (dest->x, src->x);
out.y = MAX (dest->y, src->y);
- out.width = MIN (dest->x + dest->width, src->x + src->width) - out.x;
- out.height = MIN (dest->y + dest->height, src->y + src->height) - out.y;
+ width = MIN (dest->x + dest->width, src->x + src->width) - out.x;
+ height = MIN (dest->y + dest->height, src->y + src->height) - out.y;
- if (out.width <= 0 || out.height <= 0) {
+ if (width <= 0 || height <= 0) {
dest->x = 0;
dest->y = 0;
dest->width = 0;
dest->height = 0;
} else {
+ dest->width = width;
+ dest->height = height;
*dest = out;
}
}
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