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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef SKIA_EXT_CANVAS_PAINT_LINUX_H_
#define SKIA_EXT_CANVAS_PAINT_LINUX_H_
#pragma once
#include "base/logging.h"
#include "skia/ext/canvas_paint_common.h"
#include "skia/ext/platform_canvas.h"
#include <gdk/gdk.h>
namespace skia {
// A class designed to translate skia painting into a region in a GdkWindow.
// On construction, it will set up a context for painting into, and on
// destruction, it will commit it to the GdkWindow.
// Note: The created context is always inialized to (0, 0, 0, 0).
template <class T>
class CanvasPaintT : public T {
public:
// This constructor assumes the result is opaque.
explicit CanvasPaintT(GdkEventExpose* event)
: context_(NULL),
window_(event->window),
region_(gdk_region_copy(event->region)),
composite_alpha_(false) {
init(true);
}
CanvasPaintT(GdkEventExpose* event, bool opaque)
: context_(NULL),
window_(event->window),
region_(gdk_region_copy(event->region)),
composite_alpha_(false) {
init(opaque);
}
virtual ~CanvasPaintT() {
if (!is_empty()) {
GetPlatformCanvas(this)->restoreToCount(1);
// Blit the dirty rect to the window.
CHECK(window_);
cairo_t* cr = gdk_cairo_create(window_);
CHECK(cr);
if (composite_alpha_)
cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
cairo_surface_t* source_surface = cairo_get_target(context_);
CHECK(source_surface);
// Flush cairo's cache of the surface.
cairo_surface_mark_dirty(source_surface);
GdkRectangle bounds = rectangle();
cairo_set_source_surface(cr, source_surface, bounds.x, bounds.y);
gdk_cairo_region(cr, region_);
cairo_fill(cr);
cairo_destroy(cr);
}
gdk_region_destroy(region_);
}
// Sets whether the bitmap is composited in such a way that the alpha channel
// is honored. This is only useful if you've enabled an RGBA colormap on the
// widget. The default is false.
void set_composite_alpha(bool composite_alpha) {
composite_alpha_ = composite_alpha;
}
// Returns true if the invalid region is empty. The caller should call this
// function to determine if anything needs painting.
bool is_empty() const {
return gdk_region_empty(region_);
}
GdkRectangle rectangle() const {
GdkRectangle bounds;
gdk_region_get_clipbox(region_, &bounds);
return bounds;
}
private:
void init(bool opaque) {
GdkRectangle bounds = rectangle();
PlatformCanvas* canvas = GetPlatformCanvas(this);
if (!canvas->initialize(bounds.width, bounds.height, opaque, NULL)) {
// Cause a deliberate crash;
CHECK(false);
}
// No need to clear the canvas, because cairo automatically performs the
// clear.
// Need to translate so that the dirty region appears at the origin of the
// surface.
canvas->translate(-SkIntToScalar(bounds.x), -SkIntToScalar(bounds.y));
context_ = BeginPlatformPaint(canvas);
}
cairo_t* context_;
GdkWindow* window_;
GdkRegion* region_;
// See description above setter.
bool composite_alpha_;
// Disallow copy and assign.
CanvasPaintT(const CanvasPaintT&);
CanvasPaintT& operator=(const CanvasPaintT&);
};
typedef CanvasPaintT<PlatformCanvas> PlatformCanvasPaint;
} // namespace skia
#endif // SKIA_EXT_CANVAS_PAINT_LINUX_H_
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