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diff --git a/src/cairo-gl-composite.c b/src/cairo-gl-composite.c
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+/* cairo - a vector graphics library with display and print output
+ *
+ * Copyright © 2009 Eric Anholt
+ * Copyright © 2009 Chris Wilson
+ * Copyright © 2005,2010 Red Hat, Inc
+ * Copyright © 2011 Linaro Limited
+ * Copyright © 2011 Samsung Electronics
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it either under the terms of the GNU Lesser General Public
+ * License version 2.1 as published by the Free Software Foundation
+ * (the "LGPL") or, at your option, under the terms of the Mozilla
+ * Public License Version 1.1 (the "MPL"). If you do not alter this
+ * notice, a recipient may use your version of this file under either
+ * the MPL or the LGPL.
+ *
+ * You should have received a copy of the LGPL along with this library
+ * in the file COPYING-LGPL-2.1; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
+ * You should have received a copy of the MPL along with this library
+ * in the file COPYING-MPL-1.1
+ *
+ * The contents of this file are subject to the Mozilla Public License
+ * Version 1.1 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
+ * OF ANY KIND, either express or implied. See the LGPL or the MPL for
+ * the specific language governing rights and limitations.
+ *
+ * The Original Code is the cairo graphics library.
+ *
+ * The Initial Developer of the Original Code is Red Hat, Inc.
+ *
+ * Contributor(s):
+ * Benjamin Otte <otte@gnome.org>
+ * Carl Worth <cworth@cworth.org>
+ * Chris Wilson <chris@chris-wilson.co.uk>
+ * Eric Anholt <eric@anholt.net>
+ * Alexandros Frantzis <alexandros.frantzis@linaro.org>
+ * Henry Song <hsong@sisa.samsung.com>
+ * Martin Robinson <mrobinson@igalia.com>
+ */
+
+#include "cairoint.h"
+
+#include "cairo-gl-private.h"
+
+#include "cairo-composite-rectangles-private.h"
+#include "cairo-clip-private.h"
+#include "cairo-error-private.h"
+#include "cairo-image-surface-private.h"
+
+cairo_int_status_t
+_cairo_gl_composite_set_source (cairo_gl_composite_t *setup,
+ const cairo_pattern_t *pattern,
+ const cairo_rectangle_int_t *sample,
+ const cairo_rectangle_int_t *extents,
+ cairo_bool_t use_texgen)
+{
+ _cairo_gl_operand_destroy (&setup->src);
+ return _cairo_gl_operand_init (&setup->src, pattern, setup->dst,
+ sample, extents, use_texgen);
+}
+
+void
+_cairo_gl_composite_set_source_operand (cairo_gl_composite_t *setup,
+ const cairo_gl_operand_t *source)
+{
+ _cairo_gl_operand_destroy (&setup->src);
+ _cairo_gl_operand_copy (&setup->src, source);
+}
+
+void
+_cairo_gl_composite_set_solid_source (cairo_gl_composite_t *setup,
+ const cairo_color_t *color)
+{
+ _cairo_gl_operand_destroy (&setup->src);
+ _cairo_gl_solid_operand_init (&setup->src, color);
+}
+
+cairo_int_status_t
+_cairo_gl_composite_set_mask (cairo_gl_composite_t *setup,
+ const cairo_pattern_t *pattern,
+ const cairo_rectangle_int_t *sample,
+ const cairo_rectangle_int_t *extents,
+ cairo_bool_t use_texgen)
+{
+ _cairo_gl_operand_destroy (&setup->mask);
+ if (pattern == NULL)
+ return CAIRO_STATUS_SUCCESS;
+
+ return _cairo_gl_operand_init (&setup->mask, pattern, setup->dst,
+ sample, extents, use_texgen);
+}
+
+void
+_cairo_gl_composite_set_mask_operand (cairo_gl_composite_t *setup,
+ const cairo_gl_operand_t *mask)
+{
+ _cairo_gl_operand_destroy (&setup->mask);
+ if (mask)
+ _cairo_gl_operand_copy (&setup->mask, mask);
+}
+
+void
+_cairo_gl_composite_set_spans (cairo_gl_composite_t *setup)
+{
+ setup->spans = TRUE;
+}
+
+void
+_cairo_gl_composite_set_multisample (cairo_gl_composite_t *setup)
+{
+ setup->multisample = TRUE;
+}
+
+void
+_cairo_gl_composite_set_clip_region (cairo_gl_composite_t *setup,
+ cairo_region_t *clip_region)
+{
+ setup->clip_region = clip_region;
+}
+
+void
+_cairo_gl_composite_set_clip (cairo_gl_composite_t *setup,
+ cairo_clip_t *clip)
+{
+ setup->clip = clip;
+}
+
+static void
+_cairo_gl_composite_bind_to_shader (cairo_gl_context_t *ctx,
+ cairo_gl_composite_t *setup)
+{
+ _cairo_gl_shader_bind_matrix4f(ctx, ctx->current_shader->mvp_location,
+ ctx->modelviewprojection_matrix);
+ _cairo_gl_operand_bind_to_shader (ctx, &setup->src, CAIRO_GL_TEX_SOURCE);
+ _cairo_gl_operand_bind_to_shader (ctx, &setup->mask, CAIRO_GL_TEX_MASK);
+}
+
+static void
+_cairo_gl_texture_set_filter (cairo_gl_context_t *ctx,
+ GLuint target,
+ cairo_filter_t filter)
+{
+ switch (filter) {
+ case CAIRO_FILTER_FAST:
+ case CAIRO_FILTER_NEAREST:
+ glTexParameteri (target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+ glTexParameteri (target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+ break;
+ case CAIRO_FILTER_GOOD:
+ case CAIRO_FILTER_BEST:
+ case CAIRO_FILTER_BILINEAR:
+ glTexParameteri (target, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+ glTexParameteri (target, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+ break;
+ default:
+ case CAIRO_FILTER_GAUSSIAN:
+ ASSERT_NOT_REACHED;
+ }
+}
+
+static void
+_cairo_gl_texture_set_extend (cairo_gl_context_t *ctx,
+ GLuint target,
+ cairo_extend_t extend)
+{
+ GLint wrap_mode;
+ assert (! _cairo_gl_device_requires_power_of_two_textures (&ctx->base) ||
+ (extend != CAIRO_EXTEND_REPEAT && extend != CAIRO_EXTEND_REFLECT));
+
+ switch (extend) {
+ case CAIRO_EXTEND_NONE:
+ if (ctx->gl_flavor == CAIRO_GL_FLAVOR_ES)
+ wrap_mode = GL_CLAMP_TO_EDGE;
+ else
+ wrap_mode = GL_CLAMP_TO_BORDER;
+ break;
+ case CAIRO_EXTEND_PAD:
+ wrap_mode = GL_CLAMP_TO_EDGE;
+ break;
+ case CAIRO_EXTEND_REPEAT:
+ if (ctx->has_npot_repeat)
+ wrap_mode = GL_REPEAT;
+ else
+ wrap_mode = GL_CLAMP_TO_EDGE;
+ break;
+ case CAIRO_EXTEND_REFLECT:
+ if (ctx->has_npot_repeat)
+ wrap_mode = GL_MIRRORED_REPEAT;
+ else
+ wrap_mode = GL_CLAMP_TO_EDGE;
+ break;
+ default:
+ wrap_mode = 0;
+ }
+
+ if (likely (wrap_mode)) {
+ glTexParameteri (target, GL_TEXTURE_WRAP_S, wrap_mode);
+ glTexParameteri (target, GL_TEXTURE_WRAP_T, wrap_mode);
+ }
+}
+
+
+static void
+_cairo_gl_context_setup_operand (cairo_gl_context_t *ctx,
+ cairo_gl_tex_t tex_unit,
+ cairo_gl_operand_t *operand,
+ unsigned int vertex_offset,
+ cairo_bool_t vertex_size_changed)
+{
+ cairo_gl_dispatch_t *dispatch = &ctx->dispatch;
+ cairo_bool_t needs_setup;
+
+ /* XXX: we need to do setup when switching from shaders
+ * to no shaders (or back) */
+ needs_setup = vertex_size_changed;
+ needs_setup |= _cairo_gl_operand_needs_setup (&ctx->operands[tex_unit],
+ operand,
+ vertex_offset);
+
+ if (needs_setup) {
+ _cairo_gl_composite_flush (ctx);
+ _cairo_gl_context_destroy_operand (ctx, tex_unit);
+ }
+
+ memcpy (&ctx->operands[tex_unit], operand, sizeof (cairo_gl_operand_t));
+ ctx->operands[tex_unit].vertex_offset = vertex_offset;
+
+ if (! needs_setup)
+ return;
+
+ switch (operand->type) {
+ default:
+ case CAIRO_GL_OPERAND_COUNT:
+ ASSERT_NOT_REACHED;
+ case CAIRO_GL_OPERAND_NONE:
+ break;
+ /* fall through */
+ case CAIRO_GL_OPERAND_CONSTANT:
+ break;
+ case CAIRO_GL_OPERAND_TEXTURE:
+ glActiveTexture (GL_TEXTURE0 + tex_unit);
+ glBindTexture (ctx->tex_target, operand->texture.tex);
+ _cairo_gl_texture_set_extend (ctx, ctx->tex_target,
+ operand->texture.attributes.extend);
+ _cairo_gl_texture_set_filter (ctx, ctx->tex_target,
+ operand->texture.attributes.filter);
+
+ if (! operand->texture.texgen) {
+ dispatch->VertexAttribPointer (CAIRO_GL_TEXCOORD0_ATTRIB_INDEX + tex_unit, 2,
+ GL_FLOAT, GL_FALSE, ctx->vertex_size,
+ ctx->vb + vertex_offset);
+ dispatch->EnableVertexAttribArray (CAIRO_GL_TEXCOORD0_ATTRIB_INDEX + tex_unit);
+ }
+ break;
+ case CAIRO_GL_OPERAND_LINEAR_GRADIENT:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_A0:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_NONE:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_EXT:
+ glActiveTexture (GL_TEXTURE0 + tex_unit);
+ glBindTexture (ctx->tex_target, operand->gradient.gradient->tex);
+ _cairo_gl_texture_set_extend (ctx, ctx->tex_target, operand->gradient.extend);
+ _cairo_gl_texture_set_filter (ctx, ctx->tex_target, CAIRO_FILTER_BILINEAR);
+
+ if (! operand->gradient.texgen) {
+ dispatch->VertexAttribPointer (CAIRO_GL_TEXCOORD0_ATTRIB_INDEX + tex_unit, 2,
+ GL_FLOAT, GL_FALSE, ctx->vertex_size,
+ ctx->vb + vertex_offset);
+ dispatch->EnableVertexAttribArray (CAIRO_GL_TEXCOORD0_ATTRIB_INDEX + tex_unit);
+ }
+ break;
+ }
+}
+
+static void
+_cairo_gl_context_setup_spans (cairo_gl_context_t *ctx,
+ cairo_bool_t spans_enabled,
+ unsigned int vertex_size,
+ unsigned int vertex_offset)
+{
+ cairo_gl_dispatch_t *dispatch = &ctx->dispatch;
+
+ if (! spans_enabled) {
+ dispatch->DisableVertexAttribArray (CAIRO_GL_COLOR_ATTRIB_INDEX);
+ ctx->spans = FALSE;
+ return;
+ }
+
+ dispatch->VertexAttribPointer (CAIRO_GL_COLOR_ATTRIB_INDEX, 4,
+ GL_UNSIGNED_BYTE, GL_TRUE, vertex_size,
+ ctx->vb + vertex_offset);
+ dispatch->EnableVertexAttribArray (CAIRO_GL_COLOR_ATTRIB_INDEX);
+ ctx->spans = TRUE;
+}
+
+void
+_cairo_gl_context_destroy_operand (cairo_gl_context_t *ctx,
+ cairo_gl_tex_t tex_unit)
+{
+ cairo_gl_dispatch_t *dispatch = &ctx->dispatch;
+
+ if (!_cairo_gl_context_is_flushed (ctx))
+ _cairo_gl_composite_flush (ctx);
+
+ switch (ctx->operands[tex_unit].type) {
+ default:
+ case CAIRO_GL_OPERAND_COUNT:
+ ASSERT_NOT_REACHED;
+ case CAIRO_GL_OPERAND_NONE:
+ break;
+ /* fall through */
+ case CAIRO_GL_OPERAND_CONSTANT:
+ break;
+ case CAIRO_GL_OPERAND_TEXTURE:
+ dispatch->DisableVertexAttribArray (CAIRO_GL_TEXCOORD0_ATTRIB_INDEX + tex_unit);
+ break;
+ case CAIRO_GL_OPERAND_LINEAR_GRADIENT:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_A0:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_NONE:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_EXT:
+ dispatch->DisableVertexAttribArray (CAIRO_GL_TEXCOORD0_ATTRIB_INDEX + tex_unit);
+ break;
+ }
+
+ memset (&ctx->operands[tex_unit], 0, sizeof (cairo_gl_operand_t));
+}
+
+static void
+_cairo_gl_set_operator (cairo_gl_context_t *ctx,
+ cairo_operator_t op,
+ cairo_bool_t component_alpha)
+{
+ struct {
+ GLenum src;
+ GLenum dst;
+ } blend_factors[] = {
+ { GL_ZERO, GL_ZERO }, /* Clear */
+ { GL_ONE, GL_ZERO }, /* Source */
+ { GL_ONE, GL_ONE_MINUS_SRC_ALPHA }, /* Over */
+ { GL_DST_ALPHA, GL_ZERO }, /* In */
+ { GL_ONE_MINUS_DST_ALPHA, GL_ZERO }, /* Out */
+ { GL_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA }, /* Atop */
+
+ { GL_ZERO, GL_ONE }, /* Dest */
+ { GL_ONE_MINUS_DST_ALPHA, GL_ONE }, /* DestOver */
+ { GL_ZERO, GL_SRC_ALPHA }, /* DestIn */
+ { GL_ZERO, GL_ONE_MINUS_SRC_ALPHA }, /* DestOut */
+ { GL_ONE_MINUS_DST_ALPHA, GL_SRC_ALPHA }, /* DestAtop */
+
+ { GL_ONE_MINUS_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA }, /* Xor */
+ { GL_ONE, GL_ONE }, /* Add */
+ };
+ GLenum src_factor, dst_factor;
+
+ assert (op < ARRAY_LENGTH (blend_factors));
+ /* different dst and component_alpha changes cause flushes elsewhere */
+ if (ctx->current_operator != op)
+ _cairo_gl_composite_flush (ctx);
+ ctx->current_operator = op;
+
+ src_factor = blend_factors[op].src;
+ dst_factor = blend_factors[op].dst;
+
+ /* Even when the user requests CAIRO_CONTENT_COLOR, we use GL_RGBA
+ * due to texture filtering of GL_CLAMP_TO_BORDER. So fix those
+ * bits in that case.
+ */
+ if (ctx->current_target->base.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;
+ }
+
+ if (component_alpha) {
+ if (dst_factor == GL_ONE_MINUS_SRC_ALPHA)
+ dst_factor = GL_ONE_MINUS_SRC_COLOR;
+ if (dst_factor == GL_SRC_ALPHA)
+ dst_factor = GL_SRC_COLOR;
+ }
+
+ if (ctx->current_target->base.content == CAIRO_CONTENT_ALPHA) {
+ glBlendFuncSeparate (GL_ZERO, GL_ZERO, src_factor, dst_factor);
+ } else if (ctx->current_target->base.content == CAIRO_CONTENT_COLOR) {
+ glBlendFuncSeparate (src_factor, dst_factor, GL_ONE, GL_ONE);
+ } else {
+ glBlendFunc (src_factor, dst_factor);
+ }
+}
+
+static cairo_status_t
+_cairo_gl_composite_begin_component_alpha (cairo_gl_context_t *ctx,
+ cairo_gl_composite_t *setup)
+{
+ cairo_gl_shader_t *pre_shader = NULL;
+ cairo_status_t status;
+
+ /* For CLEAR, cairo's rendering equation (quoting Owen's description in:
+ * http://lists.cairographics.org/archives/cairo/2005-August/004992.html)
+ * is:
+ * mask IN clip ? src OP dest : dest
+ * or more simply:
+ * mask IN CLIP ? 0 : dest
+ *
+ * where the ternary operator A ? B : C is (A * B) + ((1 - A) * C).
+ *
+ * The model we use in _cairo_gl_set_operator() is Render's:
+ * src IN mask IN clip OP dest
+ * which would boil down to:
+ * 0 (bounded by the extents of the drawing).
+ *
+ * However, we can do a Render operation using an opaque source
+ * and DEST_OUT to produce:
+ * 1 IN mask IN clip DEST_OUT dest
+ * which is
+ * mask IN clip ? 0 : dest
+ */
+ if (setup->op == CAIRO_OPERATOR_CLEAR) {
+ _cairo_gl_solid_operand_init (&setup->src, CAIRO_COLOR_WHITE);
+ setup->op = CAIRO_OPERATOR_DEST_OUT;
+ }
+
+ /*
+ * implements component-alpha %CAIRO_OPERATOR_OVER using two passes of
+ * the simpler operations %CAIRO_OPERATOR_DEST_OUT and %CAIRO_OPERATOR_ADD.
+ *
+ * From http://anholt.livejournal.com/32058.html:
+ *
+ * The trouble is that component-alpha rendering requires two different sources
+ * for blending: one for the source value to the blender, which is the
+ * per-channel multiplication of source and mask, and one for the source alpha
+ * for multiplying with the destination channels, which is the multiplication
+ * of the source channels by the mask alpha. So the equation for Over is:
+ *
+ * dst.A = src.A * mask.A + (1 - (src.A * mask.A)) * dst.A
+ * dst.R = src.R * mask.R + (1 - (src.A * mask.R)) * dst.R
+ * dst.G = src.G * mask.G + (1 - (src.A * mask.G)) * dst.G
+ * dst.B = src.B * mask.B + (1 - (src.A * mask.B)) * dst.B
+ *
+ * But we can do some simpler operations, right? How about PictOpOutReverse,
+ * which has a source factor of 0 and dest factor of (1 - source alpha). We
+ * can get the source alpha value (srca.X = src.A * mask.X) out of the texture
+ * blenders pretty easily. So we can do a component-alpha OutReverse, which
+ * gets us:
+ *
+ * dst.A = 0 + (1 - (src.A * mask.A)) * dst.A
+ * dst.R = 0 + (1 - (src.A * mask.R)) * dst.R
+ * dst.G = 0 + (1 - (src.A * mask.G)) * dst.G
+ * dst.B = 0 + (1 - (src.A * mask.B)) * dst.B
+ *
+ * OK. And if an op doesn't use the source alpha value for the destination
+ * factor, then we can do the channel multiplication in the texture blenders
+ * to get the source value, and ignore the source alpha that we wouldn't use.
+ * We've supported this in the Radeon driver for a long time. An example would
+ * be PictOpAdd, which does:
+ *
+ * dst.A = src.A * mask.A + dst.A
+ * dst.R = src.R * mask.R + dst.R
+ * dst.G = src.G * mask.G + dst.G
+ * dst.B = src.B * mask.B + dst.B
+ *
+ * Hey, this looks good! If we do a PictOpOutReverse and then a PictOpAdd right
+ * after it, we get:
+ *
+ * dst.A = src.A * mask.A + ((1 - (src.A * mask.A)) * dst.A)
+ * dst.R = src.R * mask.R + ((1 - (src.A * mask.R)) * dst.R)
+ * dst.G = src.G * mask.G + ((1 - (src.A * mask.G)) * dst.G)
+ * dst.B = src.B * mask.B + ((1 - (src.A * mask.B)) * dst.B)
+ *
+ * This two-pass trickery could be avoided using a new GL extension that
+ * lets two values come out of the shader and into the blend unit.
+ */
+ if (setup->op == CAIRO_OPERATOR_OVER) {
+ setup->op = CAIRO_OPERATOR_ADD;
+ status = _cairo_gl_get_shader_by_type (ctx,
+ &setup->src,
+ &setup->mask,
+ setup->spans,
+ CAIRO_GL_SHADER_IN_CA_SOURCE_ALPHA,
+ &pre_shader);
+ if (unlikely (status))
+ return status;
+ }
+
+ if (ctx->pre_shader != pre_shader)
+ _cairo_gl_composite_flush (ctx);
+ ctx->pre_shader = pre_shader;
+
+ return CAIRO_STATUS_SUCCESS;
+}
+
+static void
+_scissor_to_doubles (cairo_gl_surface_t *surface,
+ double x1, double y1,
+ double x2, double y2)
+{
+ double height;
+
+ height = y2 - y1;
+ if (_cairo_gl_surface_is_texture (surface) == FALSE)
+ y1 = surface->height - (y1 + height);
+ glScissor (x1, y1, x2 - x1, height);
+ glEnable (GL_SCISSOR_TEST);
+}
+
+void
+_cairo_gl_scissor_to_rectangle (cairo_gl_surface_t *surface,
+ const cairo_rectangle_int_t *r)
+{
+ _scissor_to_doubles (surface, r->x, r->y, r->x+r->width, r->y+r->height);
+}
+
+static void
+_scissor_to_box (cairo_gl_surface_t *surface,
+ const cairo_box_t *box)
+{
+ double x1, y1, x2, y2;
+ _cairo_box_to_doubles (box, &x1, &y1, &x2, &y2);
+ _scissor_to_doubles (surface, x1, y1, x2, y2);
+}
+
+static cairo_bool_t
+_cairo_gl_composite_setup_vbo (cairo_gl_context_t *ctx,
+ unsigned int size_per_vertex)
+{
+ cairo_bool_t vertex_size_changed = ctx->vertex_size != size_per_vertex;
+ if (vertex_size_changed) {
+ ctx->vertex_size = size_per_vertex;
+ _cairo_gl_composite_flush (ctx);
+ }
+
+ if (_cairo_gl_context_is_flushed (ctx)) {
+ ctx->dispatch.VertexAttribPointer (CAIRO_GL_VERTEX_ATTRIB_INDEX, 2,
+ GL_FLOAT, GL_FALSE, size_per_vertex,
+ ctx->vb);
+ ctx->dispatch.EnableVertexAttribArray (CAIRO_GL_VERTEX_ATTRIB_INDEX);
+ }
+
+ return vertex_size_changed;
+}
+
+static void
+_disable_stencil_buffer (void)
+{
+ glDisable (GL_STENCIL_TEST);
+ glDepthMask (GL_FALSE);
+}
+
+static cairo_int_status_t
+_cairo_gl_composite_setup_painted_clipping (cairo_gl_composite_t *setup,
+ cairo_gl_context_t *ctx,
+ int vertex_size)
+{
+ cairo_int_status_t status = CAIRO_INT_STATUS_SUCCESS;
+
+ cairo_gl_surface_t *dst = setup->dst;
+ cairo_clip_t *clip = setup->clip;
+
+ if (clip->num_boxes == 1 && clip->path == NULL) {
+ _scissor_to_box (dst, &clip->boxes[0]);
+ goto disable_stencil_buffer_and_return;
+ }
+
+ if (! _cairo_gl_ensure_stencil (ctx, setup->dst)) {
+ status = CAIRO_INT_STATUS_UNSUPPORTED;
+ goto disable_stencil_buffer_and_return;
+ }
+
+ /* We only want to clear the part of the stencil buffer
+ * that we are about to use. It also does not hurt to
+ * scissor around the painted clip. */
+ _cairo_gl_scissor_to_rectangle (dst, _cairo_clip_get_extents (clip));
+
+ /* The clip is not rectangular, so use the stencil buffer. */
+ glDepthMask (GL_TRUE);
+ glEnable (GL_STENCIL_TEST);
+
+ /* Texture surfaces have private depth/stencil buffers, so we can
+ * rely on any previous clip being cached there. */
+ if (_cairo_gl_surface_is_texture (setup->dst)) {
+ cairo_clip_t *old_clip = setup->dst->clip_on_stencil_buffer;
+ if (_cairo_clip_equal (old_clip, setup->clip))
+ goto activate_stencil_buffer_and_return;
+
+ if (old_clip) {
+ _cairo_clip_destroy (setup->dst->clip_on_stencil_buffer);
+ }
+
+ setup->dst->clip_on_stencil_buffer = _cairo_clip_copy (setup->clip);
+ }
+
+ glClearStencil (0);
+ glClear (GL_STENCIL_BUFFER_BIT);
+
+ glStencilOp (GL_REPLACE, GL_REPLACE, GL_REPLACE);
+ glStencilFunc (GL_EQUAL, 1, 0xffffffff);
+ glColorMask (0, 0, 0, 0);
+
+ status = _cairo_gl_msaa_compositor_draw_clip (ctx, setup, clip);
+
+ if (unlikely (status)) {
+ glColorMask (1, 1, 1, 1);
+ goto disable_stencil_buffer_and_return;
+ }
+
+ /* We want to only render to the stencil buffer, so draw everything now.
+ Flushing also unbinds the VBO, which we want to rebind for regular
+ drawing. */
+ _cairo_gl_composite_flush (ctx);
+ _cairo_gl_composite_setup_vbo (ctx, vertex_size);
+
+activate_stencil_buffer_and_return:
+ glColorMask (1, 1, 1, 1);
+ glStencilOp (GL_KEEP, GL_KEEP, GL_KEEP);
+ glStencilFunc (GL_EQUAL, 1, 0xffffffff);
+ return CAIRO_INT_STATUS_SUCCESS;
+
+disable_stencil_buffer_and_return:
+ _disable_stencil_buffer ();
+ return status;
+}
+
+static cairo_int_status_t
+_cairo_gl_composite_setup_clipping (cairo_gl_composite_t *setup,
+ cairo_gl_context_t *ctx,
+ int vertex_size)
+{
+ cairo_bool_t clip_changing = TRUE;
+ cairo_bool_t clip_region_changing = TRUE;
+
+ if (! ctx->clip && ! setup->clip && ! setup->clip_region && ! ctx->clip_region)
+ goto disable_all_clipping;
+
+ clip_changing = ! _cairo_clip_equal (ctx->clip, setup->clip);
+ clip_region_changing = ! cairo_region_equal (ctx->clip_region, setup->clip_region);
+ if (! _cairo_gl_context_is_flushed (ctx) &&
+ (clip_region_changing || clip_changing))
+ _cairo_gl_composite_flush (ctx);
+
+ assert (!setup->clip_region || !setup->clip);
+
+ /* setup->clip is only used by the msaa compositor and setup->clip_region
+ * only by the other compositors, so it's safe to wait to clean up obsolete
+ * clips. */
+ if (clip_region_changing) {
+ cairo_region_destroy (ctx->clip_region);
+ ctx->clip_region = cairo_region_reference (setup->clip_region);
+ }
+ if (clip_changing) {
+ _cairo_clip_destroy (ctx->clip);
+ ctx->clip = _cairo_clip_copy (setup->clip);
+ }
+
+ /* For clip regions, we scissor right before drawing. */
+ if (setup->clip_region)
+ goto disable_all_clipping;
+
+ if (setup->clip)
+ return _cairo_gl_composite_setup_painted_clipping (setup, ctx,
+ vertex_size);
+disable_all_clipping:
+ _disable_stencil_buffer ();
+ glDisable (GL_SCISSOR_TEST);
+ return CAIRO_INT_STATUS_SUCCESS;
+}
+
+cairo_status_t
+_cairo_gl_set_operands_and_operator (cairo_gl_composite_t *setup,
+ cairo_gl_context_t *ctx)
+{
+ unsigned int dst_size, src_size, mask_size, vertex_size;
+ cairo_status_t status;
+ cairo_gl_shader_t *shader;
+ cairo_bool_t component_alpha;
+ cairo_bool_t vertex_size_changed;
+
+ component_alpha =
+ setup->mask.type == CAIRO_GL_OPERAND_TEXTURE &&
+ setup->mask.texture.attributes.has_component_alpha;
+
+ /* Do various magic for component alpha */
+ if (component_alpha) {
+ status = _cairo_gl_composite_begin_component_alpha (ctx, setup);
+ if (unlikely (status))
+ return status;
+ } else {
+ if (ctx->pre_shader) {
+ _cairo_gl_composite_flush (ctx);
+ ctx->pre_shader = NULL;
+ }
+ }
+
+ status = _cairo_gl_get_shader_by_type (ctx,
+ &setup->src,
+ &setup->mask,
+ setup->spans,
+ component_alpha ?
+ CAIRO_GL_SHADER_IN_CA_SOURCE :
+ CAIRO_GL_SHADER_IN_NORMAL,
+ &shader);
+ if (unlikely (status)) {
+ ctx->pre_shader = NULL;
+ return status;
+ }
+ if (ctx->current_shader != shader)
+ _cairo_gl_composite_flush (ctx);
+
+ status = CAIRO_STATUS_SUCCESS;
+
+ dst_size = 2 * sizeof (GLfloat);
+ src_size = _cairo_gl_operand_get_vertex_size (&setup->src);
+ mask_size = _cairo_gl_operand_get_vertex_size (&setup->mask);
+ vertex_size = dst_size + src_size + mask_size;
+
+ if (setup->spans)
+ vertex_size += sizeof (GLfloat);
+
+ vertex_size_changed = _cairo_gl_composite_setup_vbo (ctx, vertex_size);
+
+ _cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_SOURCE, &setup->src, dst_size, vertex_size_changed);
+ _cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_MASK, &setup->mask, dst_size + src_size, vertex_size_changed);
+
+ _cairo_gl_context_setup_spans (ctx, setup->spans, vertex_size,
+ dst_size + src_size + mask_size);
+
+ _cairo_gl_set_operator (ctx, setup->op, component_alpha);
+
+ if (_cairo_gl_context_is_flushed (ctx)) {
+ if (ctx->pre_shader) {
+ _cairo_gl_set_shader (ctx, ctx->pre_shader);
+ _cairo_gl_composite_bind_to_shader (ctx, setup);
+ }
+ _cairo_gl_set_shader (ctx, shader);
+ _cairo_gl_composite_bind_to_shader (ctx, setup);
+ }
+
+ return status;
+}
+
+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;
+}
+
+static inline void
+_cairo_gl_composite_draw_tristrip (cairo_gl_context_t *ctx)
+{
+ cairo_array_t* indices = &ctx->tristrip_indices;
+ const unsigned short *indices_array = _cairo_array_index_const (indices, 0);
+
+ if (ctx->pre_shader) {
+ cairo_gl_shader_t *prev_shader = ctx->current_shader;
+
+ _cairo_gl_set_shader (ctx, ctx->pre_shader);
+ _cairo_gl_set_operator (ctx, CAIRO_OPERATOR_DEST_OUT, TRUE);
+ glDrawElements (GL_TRIANGLE_STRIP, _cairo_array_num_elements (indices), GL_UNSIGNED_SHORT, indices_array);
+
+ _cairo_gl_set_shader (ctx, prev_shader);
+ _cairo_gl_set_operator (ctx, CAIRO_OPERATOR_ADD, TRUE);
+ }
+
+ glDrawElements (GL_TRIANGLE_STRIP, _cairo_array_num_elements (indices), GL_UNSIGNED_SHORT, indices_array);
+ _cairo_array_truncate (indices, 0);
+}
+
+static inline void
+_cairo_gl_composite_draw_triangles (cairo_gl_context_t *ctx,
+ unsigned int count)
+{
+ if (! ctx->pre_shader) {
+ glDrawArrays (GL_TRIANGLES, 0, count);
+ } else {
+ cairo_gl_shader_t *prev_shader = ctx->current_shader;
+
+ _cairo_gl_set_shader (ctx, ctx->pre_shader);
+ _cairo_gl_set_operator (ctx, CAIRO_OPERATOR_DEST_OUT, TRUE);
+ glDrawArrays (GL_TRIANGLES, 0, count);
+
+ _cairo_gl_set_shader (ctx, prev_shader);
+ _cairo_gl_set_operator (ctx, CAIRO_OPERATOR_ADD, TRUE);
+ glDrawArrays (GL_TRIANGLES, 0, count);
+ }
+}
+
+static void
+_cairo_gl_composite_draw_triangles_with_clip_region (cairo_gl_context_t *ctx,
+ unsigned int count)
+{
+ int i, num_rectangles;
+
+ if (!ctx->clip_region) {
+ _cairo_gl_composite_draw_triangles (ctx, count);
+ return;
+ }
+
+ num_rectangles = cairo_region_num_rectangles (ctx->clip_region);
+ for (i = 0; i < num_rectangles; i++) {
+ cairo_rectangle_int_t rect;
+
+ cairo_region_get_rectangle (ctx->clip_region, i, &rect);
+
+ _cairo_gl_scissor_to_rectangle (ctx->current_target, &rect);
+ _cairo_gl_composite_draw_triangles (ctx, count);
+ }
+}
+
+static void
+_cairo_gl_composite_unmap_vertex_buffer (cairo_gl_context_t *ctx)
+{
+ ctx->vb_offset = 0;
+}
+
+void
+_cairo_gl_composite_flush (cairo_gl_context_t *ctx)
+{
+ unsigned int count;
+ int i;
+
+ if (_cairo_gl_context_is_flushed (ctx))
+ return;
+
+ count = ctx->vb_offset / ctx->vertex_size;
+ _cairo_gl_composite_unmap_vertex_buffer (ctx);
+
+ if (ctx->primitive_type == CAIRO_GL_PRIMITIVE_TYPE_TRISTRIPS) {
+ _cairo_gl_composite_draw_tristrip (ctx);
+ } else {
+ assert (ctx->primitive_type == CAIRO_GL_PRIMITIVE_TYPE_TRIANGLES);
+ _cairo_gl_composite_draw_triangles_with_clip_region (ctx, count);
+ }
+
+ for (i = 0; i < ARRAY_LENGTH (&ctx->glyph_cache); i++)
+ _cairo_gl_glyph_cache_unlock (&ctx->glyph_cache[i]);
+}
+
+static void
+_cairo_gl_composite_prepare_buffer (cairo_gl_context_t *ctx,
+ unsigned int n_vertices,
+ cairo_gl_primitive_type_t primitive_type)
+{
+ if (ctx->primitive_type != primitive_type) {
+ _cairo_gl_composite_flush (ctx);
+ ctx->primitive_type = primitive_type;
+ }
+
+ assert(ctx->vbo_size > 0);
+ if (ctx->vb_offset + n_vertices * ctx->vertex_size > ctx->vbo_size)
+ _cairo_gl_composite_flush (ctx);
+}
+
+static inline void
+_cairo_gl_composite_emit_vertex (cairo_gl_context_t *ctx,
+ GLfloat x, GLfloat y)
+{
+ GLfloat *vb = (GLfloat *) (void *) &ctx->vb[ctx->vb_offset];
+
+ *vb++ = x;
+ *vb++ = y;
+
+ _cairo_gl_operand_emit (&ctx->operands[CAIRO_GL_TEX_SOURCE], &vb, x, y);
+ _cairo_gl_operand_emit (&ctx->operands[CAIRO_GL_TEX_MASK ], &vb, x, y);
+
+ ctx->vb_offset += ctx->vertex_size;
+}
+
+static inline void
+_cairo_gl_composite_emit_alpha_vertex (cairo_gl_context_t *ctx,
+ GLfloat x, GLfloat y, uint8_t alpha)
+{
+ GLfloat *vb = (GLfloat *) (void *) &ctx->vb[ctx->vb_offset];
+ union fi {
+ float f;
+ GLbyte bytes[4];
+ } fi;
+
+ *vb++ = x;
+ *vb++ = y;
+
+ _cairo_gl_operand_emit (&ctx->operands[CAIRO_GL_TEX_SOURCE], &vb, x, y);
+ _cairo_gl_operand_emit (&ctx->operands[CAIRO_GL_TEX_MASK ], &vb, x, y);
+
+ fi.bytes[0] = 0;
+ fi.bytes[1] = 0;
+ fi.bytes[2] = 0;
+ fi.bytes[3] = alpha;
+ *vb++ = fi.f;
+
+ ctx->vb_offset += ctx->vertex_size;
+}
+
+static void
+_cairo_gl_composite_emit_point (cairo_gl_context_t *ctx,
+ const cairo_point_t *point)
+{
+ _cairo_gl_composite_emit_vertex (ctx,
+ _cairo_fixed_to_double (point->x),
+ _cairo_fixed_to_double (point->y));
+}
+
+static void
+_cairo_gl_composite_emit_rect (cairo_gl_context_t *ctx,
+ GLfloat x1, GLfloat y1,
+ GLfloat x2, GLfloat y2)
+{
+ _cairo_gl_composite_prepare_buffer (ctx, 6,
+ CAIRO_GL_PRIMITIVE_TYPE_TRIANGLES);
+
+ _cairo_gl_composite_emit_vertex (ctx, x1, y1);
+ _cairo_gl_composite_emit_vertex (ctx, x2, y1);
+ _cairo_gl_composite_emit_vertex (ctx, x1, y2);
+
+ _cairo_gl_composite_emit_vertex (ctx, x2, y1);
+ _cairo_gl_composite_emit_vertex (ctx, x2, y2);
+ _cairo_gl_composite_emit_vertex (ctx, x1, y2);
+}
+
+cairo_gl_emit_rect_t
+_cairo_gl_context_choose_emit_rect (cairo_gl_context_t *ctx)
+{
+ return _cairo_gl_composite_emit_rect;
+}
+
+void
+_cairo_gl_context_emit_rect (cairo_gl_context_t *ctx,
+ GLfloat x1, GLfloat y1,
+ GLfloat x2, GLfloat y2)
+{
+ _cairo_gl_composite_emit_rect (ctx, x1, y1, x2, y2);
+}
+
+static void
+_cairo_gl_composite_emit_span (cairo_gl_context_t *ctx,
+ GLfloat x1, GLfloat y1,
+ GLfloat x2, GLfloat y2,
+ uint8_t alpha)
+{
+ _cairo_gl_composite_prepare_buffer (ctx, 6,
+ CAIRO_GL_PRIMITIVE_TYPE_TRIANGLES);
+
+ _cairo_gl_composite_emit_alpha_vertex (ctx, x1, y1, alpha);
+ _cairo_gl_composite_emit_alpha_vertex (ctx, x2, y1, alpha);
+ _cairo_gl_composite_emit_alpha_vertex (ctx, x1, y2, alpha);
+
+ _cairo_gl_composite_emit_alpha_vertex (ctx, x2, y1, alpha);
+ _cairo_gl_composite_emit_alpha_vertex (ctx, x2, y2, alpha);
+ _cairo_gl_composite_emit_alpha_vertex (ctx, x1, y2, alpha);
+}
+
+static void
+_cairo_gl_composite_emit_solid_span (cairo_gl_context_t *ctx,
+ GLfloat x1, GLfloat y1,
+ GLfloat x2, GLfloat y2,
+ uint8_t alpha)
+{
+ GLfloat *v;
+ union fi {
+ float f;
+ GLbyte bytes[4];
+ } fi;
+
+ _cairo_gl_composite_prepare_buffer (ctx, 6,
+ CAIRO_GL_PRIMITIVE_TYPE_TRIANGLES);
+ v = (GLfloat *) (void *) &ctx->vb[ctx->vb_offset];
+
+ v[15] = v[ 6] = v[0] = x1;
+ v[10] = v[ 4] = v[1] = y1;
+ v[12] = v[ 9] = v[3] = x2;
+ v[16] = v[13] = v[7] = y2;
+
+ fi.bytes[0] = 0;
+ fi.bytes[1] = 0;
+ fi.bytes[2] = 0;
+ fi.bytes[3] = alpha;
+ v[17] =v[14] = v[11] = v[8] = v[5] = v[2] = fi.f;
+
+ ctx->vb_offset += 6*3 * sizeof(GLfloat);
+}
+
+cairo_gl_emit_span_t
+_cairo_gl_context_choose_emit_span (cairo_gl_context_t *ctx)
+{
+ if (ctx->operands[CAIRO_GL_TEX_MASK].type != CAIRO_GL_OPERAND_NONE) {
+ switch (ctx->operands[CAIRO_GL_TEX_MASK].type) {
+ default:
+ case CAIRO_GL_OPERAND_COUNT:
+ ASSERT_NOT_REACHED;
+ case CAIRO_GL_OPERAND_NONE:
+ case CAIRO_GL_OPERAND_CONSTANT:
+ break;
+
+ case CAIRO_GL_OPERAND_LINEAR_GRADIENT:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_A0:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_NONE:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_EXT:
+ if (!ctx->operands[CAIRO_GL_TEX_MASK].gradient.texgen)
+ return _cairo_gl_composite_emit_span;
+ break;
+
+ case CAIRO_GL_OPERAND_TEXTURE:
+ if (!ctx->operands[CAIRO_GL_TEX_MASK].texture.texgen)
+ return _cairo_gl_composite_emit_span;
+ break;
+ }
+ }
+
+ switch (ctx->operands[CAIRO_GL_TEX_SOURCE].type) {
+ default:
+ case CAIRO_GL_OPERAND_COUNT:
+ ASSERT_NOT_REACHED;
+ case CAIRO_GL_OPERAND_NONE:
+ case CAIRO_GL_OPERAND_CONSTANT:
+ break;
+
+ case CAIRO_GL_OPERAND_LINEAR_GRADIENT:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_A0:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_NONE:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_EXT:
+ if (!ctx->operands[CAIRO_GL_TEX_SOURCE].gradient.texgen)
+ return _cairo_gl_composite_emit_span;
+ break;
+
+ case CAIRO_GL_OPERAND_TEXTURE:
+ if (!ctx->operands[CAIRO_GL_TEX_SOURCE].texture.texgen)
+ return _cairo_gl_composite_emit_span;
+ }
+
+ return _cairo_gl_composite_emit_solid_span;
+}
+
+static inline void
+_cairo_gl_composite_emit_glyph_vertex (cairo_gl_context_t *ctx,
+ GLfloat x, GLfloat y,
+ GLfloat glyph_x, GLfloat glyph_y)
+{
+ GLfloat *vb = (GLfloat *) (void *) &ctx->vb[ctx->vb_offset];
+
+ *vb++ = x;
+ *vb++ = y;
+
+ _cairo_gl_operand_emit (&ctx->operands[CAIRO_GL_TEX_SOURCE], &vb, x, y);
+
+ *vb++ = glyph_x;
+ *vb++ = glyph_y;
+
+ ctx->vb_offset += ctx->vertex_size;
+}
+
+static void
+_cairo_gl_composite_emit_glyph (cairo_gl_context_t *ctx,
+ GLfloat x1, GLfloat y1,
+ GLfloat x2, GLfloat y2,
+ GLfloat glyph_x1, GLfloat glyph_y1,
+ GLfloat glyph_x2, GLfloat glyph_y2)
+{
+ _cairo_gl_composite_prepare_buffer (ctx, 6,
+ CAIRO_GL_PRIMITIVE_TYPE_TRIANGLES);
+
+ _cairo_gl_composite_emit_glyph_vertex (ctx, x1, y1, glyph_x1, glyph_y1);
+ _cairo_gl_composite_emit_glyph_vertex (ctx, x2, y1, glyph_x2, glyph_y1);
+ _cairo_gl_composite_emit_glyph_vertex (ctx, x1, y2, glyph_x1, glyph_y2);
+
+ _cairo_gl_composite_emit_glyph_vertex (ctx, x2, y1, glyph_x2, glyph_y1);
+ _cairo_gl_composite_emit_glyph_vertex (ctx, x2, y2, glyph_x2, glyph_y2);
+ _cairo_gl_composite_emit_glyph_vertex (ctx, x1, y2, glyph_x1, glyph_y2);
+}
+
+static void
+_cairo_gl_composite_emit_solid_glyph (cairo_gl_context_t *ctx,
+ GLfloat x1, GLfloat y1,
+ GLfloat x2, GLfloat y2,
+ GLfloat glyph_x1, GLfloat glyph_y1,
+ GLfloat glyph_x2, GLfloat glyph_y2)
+{
+ GLfloat *v;
+
+ _cairo_gl_composite_prepare_buffer (ctx, 6,
+ CAIRO_GL_PRIMITIVE_TYPE_TRIANGLES);
+
+ v = (GLfloat *) (void *) &ctx->vb[ctx->vb_offset];
+
+ v[20] = v[ 8] = v[0] = x1;
+ v[13] = v[ 5] = v[1] = y1;
+ v[22] = v[10] = v[2] = glyph_x1;
+ v[15] = v[ 7] = v[3] = glyph_y1;
+
+ v[16] = v[12] = v[4] = x2;
+ v[18] = v[14] = v[6] = glyph_x2;
+
+ v[21] = v[17] = v[ 9] = y2;
+ v[23] = v[19] = v[11] = glyph_y2;
+
+ ctx->vb_offset += 4 * 6 * sizeof (GLfloat);
+}
+
+cairo_gl_emit_glyph_t
+_cairo_gl_context_choose_emit_glyph (cairo_gl_context_t *ctx)
+{
+ switch (ctx->operands[CAIRO_GL_TEX_SOURCE].type) {
+ default:
+ case CAIRO_GL_OPERAND_COUNT:
+ ASSERT_NOT_REACHED;
+ case CAIRO_GL_OPERAND_NONE:
+ case CAIRO_GL_OPERAND_CONSTANT:
+ return _cairo_gl_composite_emit_solid_glyph;
+
+ case CAIRO_GL_OPERAND_LINEAR_GRADIENT:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_A0:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_NONE:
+ case CAIRO_GL_OPERAND_RADIAL_GRADIENT_EXT:
+ case CAIRO_GL_OPERAND_TEXTURE:
+ return _cairo_gl_composite_emit_glyph;
+ }
+}
+
+void
+_cairo_gl_composite_fini (cairo_gl_composite_t *setup)
+{
+ _cairo_gl_operand_destroy (&setup->src);
+ _cairo_gl_operand_destroy (&setup->mask);
+}
+
+cairo_status_t
+_cairo_gl_composite_set_operator (cairo_gl_composite_t *setup,
+ cairo_operator_t op,
+ cairo_bool_t assume_component_alpha)
+{
+ if (assume_component_alpha) {
+ if (op != CAIRO_OPERATOR_CLEAR &&
+ op != CAIRO_OPERATOR_OVER &&
+ op != CAIRO_OPERATOR_ADD)
+ return UNSUPPORTED ("unsupported component alpha operator");
+ } else {
+ if (! _cairo_gl_operator_is_supported (op))
+ return UNSUPPORTED ("unsupported operator");
+ }
+
+ setup->op = op;
+ return CAIRO_STATUS_SUCCESS;
+}
+
+cairo_status_t
+_cairo_gl_composite_init (cairo_gl_composite_t *setup,
+ cairo_operator_t op,
+ cairo_gl_surface_t *dst,
+ cairo_bool_t assume_component_alpha)
+{
+ cairo_status_t status;
+
+ memset (setup, 0, sizeof (cairo_gl_composite_t));
+
+ status = _cairo_gl_composite_set_operator (setup, op,
+ assume_component_alpha);
+ if (status)
+ return status;
+
+ setup->dst = dst;
+ setup->clip_region = dst->clip_region;
+
+ return CAIRO_STATUS_SUCCESS;
+}
+
+static cairo_int_status_t
+_cairo_gl_composite_append_vertex_indices (cairo_gl_context_t *ctx,
+ int number_of_new_indices)
+{
+ cairo_int_status_t status = CAIRO_INT_STATUS_SUCCESS;
+ cairo_array_t *indices = &ctx->tristrip_indices;
+ int number_of_indices = _cairo_array_num_elements (indices);
+ unsigned short current_vertex_index = 0;
+ int i;
+
+ assert (number_of_new_indices > 0);
+
+ /* If any preexisting triangle triangle strip indices exist on this
+ context, we insert a set of degenerate triangles from the last
+ preexisting vertex to our first one. */
+ if (number_of_indices > 0) {
+ const unsigned short *indices_array = _cairo_array_index_const (indices, 0);
+ current_vertex_index = indices_array[number_of_indices - 1];
+
+ status = _cairo_array_append (indices, &current_vertex_index);
+ if (unlikely (status))
+ return status;
+
+ current_vertex_index++;
+ status =_cairo_array_append (indices, &current_vertex_index);
+ if (unlikely (status))
+ return status;
+ }
+
+ for (i = 0; i < number_of_new_indices; i++) {
+ status = _cairo_array_append (indices, &current_vertex_index);
+ current_vertex_index++;
+ if (unlikely (status))
+ return status;
+ }
+
+ return CAIRO_STATUS_SUCCESS;
+}
+
+cairo_int_status_t
+_cairo_gl_composite_emit_quad_as_tristrip (cairo_gl_context_t *ctx,
+ cairo_gl_composite_t *setup,
+ const cairo_point_t quad[4])
+{
+ _cairo_gl_composite_prepare_buffer (ctx, 4,
+ CAIRO_GL_PRIMITIVE_TYPE_TRISTRIPS);
+
+ _cairo_gl_composite_emit_point (ctx, &quad[0]);
+ _cairo_gl_composite_emit_point (ctx, &quad[1]);
+
+ /* Cairo stores quad vertices in counter-clockwise order, but we need to
+ emit them from top to bottom in the triangle strip, so we need to reverse
+ the order of the last two vertices. */
+ _cairo_gl_composite_emit_point (ctx, &quad[3]);
+ _cairo_gl_composite_emit_point (ctx, &quad[2]);
+
+ return _cairo_gl_composite_append_vertex_indices (ctx, 4);
+}
+
+cairo_int_status_t
+_cairo_gl_composite_emit_triangle_as_tristrip (cairo_gl_context_t *ctx,
+ cairo_gl_composite_t *setup,
+ const cairo_point_t triangle[3])
+{
+ _cairo_gl_composite_prepare_buffer (ctx, 3,
+ CAIRO_GL_PRIMITIVE_TYPE_TRISTRIPS);
+
+ _cairo_gl_composite_emit_point (ctx, &triangle[0]);
+ _cairo_gl_composite_emit_point (ctx, &triangle[1]);
+ _cairo_gl_composite_emit_point (ctx, &triangle[2]);
+ return _cairo_gl_composite_append_vertex_indices (ctx, 3);
+}