clip: Rudimentary support for clip-polygon extraction

Step 1, fix the failings sighted recently by tracking clip-boxes as an
explicit property of the clipping and of composition.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 142 insertions, 0 deletions

diff --git a/src/cairo-clip-surface.c b/src/cairo-clip-surface.c
new file mode 100644
index 000000000..79e6a6274
--- /dev/null
+++ b/src/cairo-clip-surface.c
@@ -0,0 +1,142 @@
+/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
+/* cairo - a vector graphics library with display and print output
+ *
+ * Copyright © 2002 University of Southern California
+ * Copyright © 2005 Red Hat, Inc.
+ * Copyright © 2009 Chris Wilson
+ *
+ * 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 University of Southern
+ * California.
+ *
+ * Contributor(s):
+ *	Carl D. Worth <cworth@cworth.org>
+ *	Kristian Høgsberg <krh@redhat.com>
+ *	Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#include "cairoint.h"
+#include "cairo-clip-private.h"
+#include "cairo-error-private.h"
+#include "cairo-freed-pool-private.h"
+#include "cairo-gstate-private.h"
+#include "cairo-path-fixed-private.h"
+#include "cairo-pattern-private.h"
+#include "cairo-composite-rectangles-private.h"
+#include "cairo-region-private.h"
+
+cairo_status_t
+_cairo_clip_combine_with_surface (const cairo_clip_t *clip,
+				  cairo_surface_t *dst,
+				  int dst_x, int dst_y)
+{
+    cairo_clip_path_t *clip_path;
+    cairo_clip_path_t *copy_path;
+    cairo_clip_t *copy;
+    cairo_status_t status = CAIRO_STATUS_SUCCESS;
+
+    copy = _cairo_clip_copy_with_translation (clip, -dst_x, -dst_y);
+    copy_path = copy->path;
+    copy->path = NULL;
+
+    if (copy_path == NULL) {
+	assert (copy->num_boxes);
+	status = _cairo_surface_paint (dst,
+				       CAIRO_OPERATOR_IN,
+				       &_cairo_pattern_white.base,
+				       copy);
+    }
+
+    clip_path = copy_path;
+    while (status == CAIRO_STATUS_SUCCESS && clip_path) {
+	status = _cairo_surface_fill (dst,
+				      CAIRO_OPERATOR_IN,
+				      &_cairo_pattern_white.base,
+				      &clip_path->path,
+				      clip_path->fill_rule,
+				      clip_path->tolerance,
+				      clip_path->antialias,
+				      copy);
+	clip_path = clip_path->prev;
+    }
+
+    copy->path = copy_path;
+    _cairo_clip_destroy (copy);
+    return status;
+}
+
+cairo_surface_t *
+_cairo_clip_get_surface (const cairo_clip_t *clip,
+			 cairo_surface_t *target,
+			 int *tx, int *ty)
+{
+    cairo_surface_t *surface;
+    cairo_status_t status;
+    cairo_clip_t *copy;
+    cairo_clip_path_t *copy_path, *clip_path;
+
+    surface = _cairo_surface_create_similar_solid (target,
+						   CAIRO_CONTENT_ALPHA,
+						   clip->extents.width,
+						   clip->extents.height,
+						   CAIRO_COLOR_TRANSPARENT,
+						   TRUE);
+    if (unlikely (surface->status))
+	return surface;
+
+    copy = _cairo_clip_copy_with_translation (clip,
+					      -clip->extents.x,
+					      -clip->extents.y);
+    copy_path = copy->path;
+    copy->path = NULL;
+
+    assert (copy->num_boxes);
+    status = _cairo_surface_paint (surface,
+				   CAIRO_OPERATOR_ADD,
+				   &_cairo_pattern_white.base,
+				   copy);
+
+    clip_path = copy_path;
+    while (status == CAIRO_STATUS_SUCCESS && clip_path) {
+	status = _cairo_surface_fill (surface,
+				      CAIRO_OPERATOR_IN,
+				      &_cairo_pattern_white.base,
+				      &clip_path->path,
+				      clip_path->fill_rule,
+				      clip_path->tolerance,
+				      clip_path->antialias,
+				      copy);
+	clip_path = clip_path->prev;
+    }
+
+    copy->path = copy_path;
+    _cairo_clip_destroy (copy);
+
+    *tx = clip->extents.x;
+    *ty = clip->extents.y;
+    return surface;
+}