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[gl] Wire blend factors using dst alpha to constants for CAIRO_CONTENT_COLOR.

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This fixes the operator and operator-alpha tests to rgb24 destinations.
While we request an RGB texture, the returned texture has alpha bits, so when
we blend against it as a renderbuffer, we get the junk alpha values.  Whether
or not this is a driver bug, we'll have this problem when we get visuals
with alpha bits for windows despite not requestiong alpha, so we have to
handle it in cairo.
This commit is contained in:
Eric Anholt 2009-03-28 21:53:04 -07:00
parent 809f7dc4c8
commit 979337dd4d
1 changed files with 18 additions and 4 deletions
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22
src/cairo-gl-surface.c
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@ -246,7 +246,7 @@ _cairo_gl_set_destination (cairo_gl_surface_t *surface)
}
static int
_cairo_gl_set_operator (cairo_operator_t op)
_cairo_gl_set_operator (cairo_gl_surface_t *dst, cairo_operator_t op)
{
struct {
GLenum src;
@ -268,11 +268,25 @@ _cairo_gl_set_operator (cairo_operator_t op)
{ GL_ONE_MINUS_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA }, /* Xor */
{ GL_ONE, GL_ONE }, /* Add */
};
GLenum src_factor, dst_factor;
if (op >= ARRAY_SIZE (blend_factors))
return CAIRO_INT_STATUS_UNSUPPORTED;
glBlendFunc (blend_factors[op].src, blend_factors[op].dst);
src_factor = blend_factors[op].src;
dst_factor = blend_factors[op].dst;
/* We may have a visual with alpha bits despite the user requesting
* CAIRO_CONTENT_COLOR. So clear out those bits in that case.
*/
if (dst->content == CAIRO_CONTENT_COLOR) {
if (src_factor == GL_ONE_MINUS_DST_ALPHA)
src_factor = GL_ZERO;
if (src_factor == GL_DST_ALPHA)
src_factor = GL_ONE;
}
glBlendFunc (src_factor, dst_factor);
return CAIRO_STATUS_SUCCESS;
}
@ -1214,7 +1228,7 @@ _cairo_gl_surface_composite (cairo_operator_t op,
ctx = _cairo_gl_context_acquire (dst->ctx);
_cairo_gl_set_destination (dst);
status = _cairo_gl_set_operator (op);
status = _cairo_gl_set_operator (dst, op);
if (status != CAIRO_STATUS_SUCCESS) {
_cairo_gl_operand_destroy (&setup.src);
if (mask != NULL)
@ -1409,7 +1423,7 @@ _cairo_gl_surface_fill_rectangles (void *abstract_surface,
ctx = _cairo_gl_context_acquire (surface->ctx);
_cairo_gl_set_destination (surface);
status = _cairo_gl_set_operator (op);
status = _cairo_gl_set_operator (surface, op);
if (status != CAIRO_STATUS_SUCCESS) {
_cairo_gl_context_release (ctx);
return status;