cairo_status_t
_cairo_gl_composite_begin (cairo_gl_composite_t *setup,
cairo_gl_context_t **ctx_out)
{
cairo_gl_context_t *ctx;
cairo_status_t status;
assert (setup->dst);
status = _cairo_gl_context_acquire (setup->dst->base.device, &ctx);
if (unlikely (status))
return status;
_cairo_gl_context_set_destination (ctx, setup->dst, setup->multisample);
glEnable (GL_BLEND);
status = _cairo_gl_set_operands_and_operator (setup, ctx);
if (unlikely (status))
goto FAIL;
status = _cairo_gl_composite_setup_clipping (setup, ctx, ctx->vertex_size);
if (unlikely (status))
goto FAIL;
*ctx_out = ctx;
FAIL:
if (unlikely (status))
status = _cairo_gl_context_release (ctx, status);
return status;
}
/* Masking with the SOURCE operator requires two passes. In the first
* pass we use the mask as the source to get:
* result = (1 - ma) * dst
* In the second pass we use the add operator to achieve:
* result = (src * ma) + dst
* Combined this produces:
* result = (src * ma) + (1 - ma) * dst
*/
static cairo_int_status_t
_cairo_gl_msaa_compositor_mask_source_operator (const cairo_compositor_t *compositor,
cairo_composite_rectangles_t *composite)
{
cairo_gl_composite_t setup;
cairo_gl_surface_t *dst = (cairo_gl_surface_t *) composite->surface;
cairo_gl_context_t *ctx = NULL;
cairo_int_status_t status;
cairo_clip_t *clip = composite->clip;
cairo_traps_t traps;
/* If we have a non-rectangular clip, we can avoid using the stencil buffer
* for clipping and just draw the clip polygon. */
if (clip) {
status = _clip_to_traps (clip, &traps);
if (unlikely (status)) {
_cairo_traps_fini (&traps);
return status;
}
}
status = _cairo_gl_composite_init (&setup,
CAIRO_OPERATOR_DEST_OUT,
dst,
FALSE /* assume_component_alpha */);
if (unlikely (status))
return status;
status = _cairo_gl_composite_set_source (&setup,
&composite->mask_pattern.base,
&composite->mask_sample_area,
&composite->bounded,
FALSE);
if (unlikely (status))
goto finish;
_cairo_gl_composite_set_multisample (&setup);
status = _cairo_gl_composite_begin (&setup, &ctx);
if (unlikely (status))
goto finish;
if (! clip)
status = _draw_int_rect (ctx, &setup, &composite->bounded);
else
status = _draw_traps (ctx, &setup, &traps);
/* Now draw the second pass. */
_cairo_gl_composite_set_operator (&setup, CAIRO_OPERATOR_ADD,
FALSE /* assume_component_alpha */);
if (unlikely (status))
goto finish;
status = _cairo_gl_composite_set_source (&setup,
&composite->source_pattern.base,
&composite->source_sample_area,
&composite->bounded,
FALSE);
if (unlikely (status))
goto finish;
status = _cairo_gl_composite_set_mask (&setup,
&composite->mask_pattern.base,
&composite->source_sample_area,
&composite->bounded,
FALSE);
if (unlikely (status))
goto finish;
status = _cairo_gl_set_operands_and_operator (&setup, ctx);
if (unlikely (status))
goto finish;
if (! clip)
status = _draw_int_rect (ctx, &setup, &composite->bounded);
else
status = _draw_traps (ctx, &setup, &traps);
finish:
_cairo_gl_composite_fini (&setup);
if (ctx)
status = _cairo_gl_context_release (ctx, status);
if (clip)
_cairo_traps_fini (&traps);
return status;
}
