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// Copyright (c) 2009 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_
#include "skia/ext/platform_canvas.h"
namespace skia {
// A class designed to translate skia painting into a region in a
// GdkWindow. This class has been adapted from the class with the same name in
// platform_canvas_win.h. On construction, it will set up a context for
// painting into, and on destruction, it will commit it to the GdkWindow.
template <class T>
class CanvasPaintT : public T {
public:
// This constructor assumes the result is opaque.
explicit CanvasPaintT(GdkEventExpose* event)
: surface_(NULL),
window_(event->window),
rectangle_(event->area),
composite_alpha_(false) {
init(true);
}
CanvasPaintT(GdkEventExpose* event, bool opaque)
: surface_(NULL),
window_(event->window),
rectangle_(event->area),
composite_alpha_(false) {
init(opaque);
}
virtual ~CanvasPaintT() {
if (!is_empty()) {
T::restoreToCount(1);
// Blit the dirty rect to the window.
cairo_t* cr = gdk_cairo_create(window_);
if (composite_alpha_)
cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
cairo_set_source_surface(cr, surface_, rectangle_.x, rectangle_.y);
cairo_rectangle(cr, rectangle_.x, rectangle_.y,
rectangle_.width, rectangle_.height);
cairo_fill(cr);
cairo_destroy(cr);
}
}
// 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 rectangle_.width == 0 || rectangle_.height == 0;
}
const GdkRectangle& rectangle() const {
return rectangle_;
}
private:
void init(bool opaque) {
if (!T::initialize(rectangle_.width, rectangle_.height, opaque, NULL)) {
// Cause a deliberate crash;
*(char*) 0 = 0;
}
// Need to translate so that the dirty region appears at the origin of the
// surface.
T::translate(-SkIntToScalar(rectangle_.x), -SkIntToScalar(rectangle_.y));
surface_ = T::getTopPlatformDevice().beginPlatformPaint();
}
cairo_surface_t* surface_;
GdkWindow* window_;
GdkRectangle rectangle_;
// 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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