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changeset: 106848:28db6dbdd9ea
tag: gdi-patch
tag: qbase
tag: qtip
tag: tip
user: Jeff Muizelaar <jmuizelaar@mozilla.com>
date: Wed Sep 12 22:52:06 2012 -0400
summary: Bug 788794. Use BitBlt to do SOURCE and OVER from RGB24 to ARGB32. r=nical
diff --git a/gfx/cairo/cairo/src/cairo-win32-surface.c b/gfx/cairo/cairo/src/cairo-win32-surface.c
--- a/gfx/cairo/cairo/src/cairo-win32-surface.c
+++ b/gfx/cairo/cairo/src/cairo-win32-surface.c
@@ -884,16 +884,28 @@ static cairo_int_status_t
src_x, src_y,
src_w, src_h,
blend_function))
return _cairo_win32_print_gdi_error ("_cairo_win32_surface_composite(AlphaBlend)");
return CAIRO_STATUS_SUCCESS;
}
+/* makes the alpha channel in a RGB24 surface 0xff */
+static void
+make_opaque (cairo_image_surface_t *image, cairo_rectangle_int_t src_r)
+{
+ int x; int y;
+ for (y = src_r.y; y < src_r.height; y++) {
+ for (x = src_r.x; x < src_r.width; x++) {
+ image->data[y * image->stride + x*4 + 3] = 0xff;
+ }
+ }
+}
+
static cairo_int_status_t
_cairo_win32_surface_composite_inner (cairo_win32_surface_t *src,
cairo_image_surface_t *src_image,
cairo_win32_surface_t *dst,
cairo_rectangle_int_t src_extents,
cairo_rectangle_int_t src_r,
cairo_rectangle_int_t dst_r,
int alpha,
@@ -935,16 +947,24 @@ static cairo_int_status_t
src_r.width, - (int) src_r.height,
src_image->data,
&bi,
DIB_RGB_COLORS,
SRCCOPY))
return _cairo_win32_print_gdi_error ("_cairo_win32_surface_composite(StretchDIBits)");
}
} else if (!needs_alpha) {
+ if (src->format == CAIRO_FORMAT_RGB24 && dst->format == CAIRO_FORMAT_ARGB32) {
+ /* Because we store RGB24 & ARGB32 in the same way GDI has no way
+ * to ignore the alpha channel from a RGB24 source. Therefore, we set
+ * the alpha channel in our RGB24 source to opaque so that we can treat
+ * it like ARGB32. */
+ GdiFlush();
+ make_opaque(src->image, src_r);
+ }
/* BitBlt or StretchBlt? */
if (!needs_scale && (dst->flags & CAIRO_WIN32_SURFACE_CAN_BITBLT)) {
if (!BitBlt (dst->dc,
dst_r.x, dst_r.y,
dst_r.width, dst_r.height,
src->dc,
src_r.x, src_r.y,
SRCCOPY))
@@ -1184,28 +1204,36 @@ static cairo_int_status_t
}
} else {
needs_repeat = TRUE;
}
/*
* Operations that we can do:
*
+ * AlphaBlend uses the following formula for alpha when not use the per-pixel alpha (AlphaFormat = 0)
+ * Dst.Alpha = Src.Alpha * (SCA/255.0) + Dst.Alpha * (1.0 - (SCA/255.0))
+ * This turns into Dst.Alpha = Src.Alpha when SCA = 255.
+ * (http://msdn.microsoft.com/en-us/library/aa921335.aspx)
+ *
* RGB OVER RGB -> BitBlt (same as SOURCE)
- * RGB OVER ARGB -> UNSUPPORTED (AlphaBlend treats this as a BitBlt, even with SCA 255 and no AC_SRC_ALPHA)
+ * RGB OVER ARGB -> Partially supported, We convert this operation into a ARGB SOURCE ARGB
+ * by setting the alpha values of the source to 255.
* ARGB OVER ARGB -> AlphaBlend, with AC_SRC_ALPHA
* ARGB OVER RGB -> AlphaBlend, with AC_SRC_ALPHA; we'll have junk in the dst A byte
*
* RGB OVER RGB + mask -> AlphaBlend, no AC_SRC_ALPHA
- * RGB OVER ARGB + mask -> UNSUPPORTED
+ * RGB OVER ARGB + mask -> Partially supported, We convert this operation into a ARGB OVER ARGB + mask
+ * by setting the alpha values of the source to 255.
* ARGB OVER ARGB + mask -> AlphaBlend, with AC_SRC_ALPHA
* ARGB OVER RGB + mask -> AlphaBlend, with AC_SRC_ALPHA; junk in the dst A byte
*
* RGB SOURCE RGB -> BitBlt
- * RGB SOURCE ARGB -> UNSUPPORTED (AlphaBlend treats this as a BitBlt, even with SCA 255 and no AC_SRC_ALPHA)
+ * RGB SOURCE ARGB -> Partially supported, We convert this operation into a ARGB SOURCE ARGB
+ * by setting the alpha values of the source to 255.
* ARGB SOURCE ARGB -> BitBlt
* ARGB SOURCE RGB -> BitBlt
*
* RGB SOURCE RGB + mask -> unsupported
* RGB SOURCE ARGB + mask -> unsupported
* ARGB SOURCE ARGB + mask -> unsupported
* ARGB SOURCE RGB + mask -> unsupported
*/
@@ -1222,22 +1250,32 @@ static cairo_int_status_t
needs_alpha = FALSE;
} else {
needs_alpha = TRUE;
}
} else if (src_format == CAIRO_FORMAT_ARGB32 &&
dst->format == CAIRO_FORMAT_RGB24)
{
needs_alpha = TRUE;
+ } else if (src_format == CAIRO_FORMAT_RGB24 &&
+ dst->format == CAIRO_FORMAT_ARGB32 &&
+ src->image)
+ {
+ if (alpha == 255) {
+ needs_alpha = FALSE;
+ } else {
+ needs_alpha = TRUE;
+ }
} else {
goto UNSUPPORTED;
}
} else if (alpha == 255 && op == CAIRO_OPERATOR_SOURCE) {
if ((src_format == dst->format) ||
- (src_format == CAIRO_FORMAT_ARGB32 && dst->format == CAIRO_FORMAT_RGB24))
+ (src_format == CAIRO_FORMAT_ARGB32 && dst->format == CAIRO_FORMAT_RGB24) ||
+ (src_format == CAIRO_FORMAT_RGB24 && dst->format == CAIRO_FORMAT_ARGB32 && src->image))
{
needs_alpha = FALSE;
} else {
goto UNSUPPORTED;
}
} else {
goto UNSUPPORTED;
}
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