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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_PLATFORM_CANVAS_H_
#define SKIA_EXT_PLATFORM_CANVAS_H_
#include <stddef.h>
#include <stdint.h>
// The platform-specific device will include the necessary platform headers
// to get the surface type.
#include "build/build_config.h"
#include "skia/ext/platform_surface.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "third_party/skia/include/core/SkCanvas.h"
#include "third_party/skia/include/core/SkPixelRef.h"
#include "third_party/skia/include/core/SkPixmap.h"
class SkBaseDevice;
// A PlatformCanvas is a software-rasterized SkCanvas which is *also*
// addressable by the platform-specific drawing API (GDI, Core Graphics,
// Cairo...).
namespace skia {
//
// Note about error handling.
//
// Creating a canvas can fail at times, most often because we fail to allocate
// the backing-store (pixels). This can be from out-of-memory, or something
// more opaque, like GDI or cairo reported a failure.
//
// To allow the caller to handle the failure, every Create... factory takes an
// enum as its last parameter. The default value is kCrashOnFailure. If the
// caller passes kReturnNullOnFailure, then the caller is responsible to check
// the return result.
//
enum OnFailureType {
CRASH_ON_FAILURE,
RETURN_NULL_ON_FAILURE
};
#if defined(WIN32)
// The shared_section parameter is passed to gfx::PlatformDevice::create.
// See it for details.
SK_API SkCanvas* CreatePlatformCanvas(int width,
int height,
bool is_opaque,
HANDLE shared_section,
OnFailureType failure_type);
// Draws the top layer of the canvas into the specified HDC. Only works
// with a SkCanvas with a BitmapPlatformDevice. Will create a temporary
// HDC to back the canvas if one doesn't already exist, tearing it down
// before returning. If |src_rect| is null, copies the entire canvas.
SK_API void DrawToNativeContext(SkCanvas* canvas,
HDC hdc,
int x,
int y,
const RECT* src_rect);
#elif defined(__APPLE__)
SK_API SkCanvas* CreatePlatformCanvas(CGContextRef context,
int width,
int height,
bool is_opaque,
OnFailureType failure_type);
SK_API SkCanvas* CreatePlatformCanvas(int width,
int height,
bool is_opaque,
uint8_t* context,
OnFailureType failure_type);
#elif defined(__linux__) || defined(__FreeBSD__) || defined(__OpenBSD__) || \
defined(__sun) || defined(ANDROID)
// Linux ---------------------------------------------------------------------
// Construct a canvas from the given memory region. The memory is not cleared
// first. @data must be, at least, @height * StrideForWidth(@width) bytes.
SK_API SkCanvas* CreatePlatformCanvas(int width,
int height,
bool is_opaque,
uint8_t* data,
OnFailureType failure_type);
#endif
static inline SkCanvas* CreatePlatformCanvas(int width,
int height,
bool is_opaque) {
return CreatePlatformCanvas(width, height, is_opaque, 0, CRASH_ON_FAILURE);
}
SK_API SkCanvas* CreateCanvas(const sk_sp<SkBaseDevice>& device,
OnFailureType failure_type);
static inline SkCanvas* CreateBitmapCanvas(int width,
int height,
bool is_opaque) {
return CreatePlatformCanvas(width, height, is_opaque, 0, CRASH_ON_FAILURE);
}
static inline SkCanvas* TryCreateBitmapCanvas(int width,
int height,
bool is_opaque) {
return CreatePlatformCanvas(width, height, is_opaque, 0,
RETURN_NULL_ON_FAILURE);
}
// Return the stride (length of a line in bytes) for the given width. Because
// we use 32-bits per pixel, this will be roughly 4*width. However, for
// alignment reasons we may wish to increase that.
SK_API size_t PlatformCanvasStrideForWidth(unsigned width);
// Copies pixels from the SkCanvas into an SkBitmap, fetching pixels from
// GPU memory if necessary.
//
// The bitmap will remain empty if we can't allocate enough memory for a copy
// of the pixels.
SK_API SkBitmap ReadPixels(SkCanvas* canvas);
// Gives the pixmap passed in *writable* access to the pixels backing this
// canvas. All writes to the pixmap should be visible if the canvas is
// raster-backed.
//
// Returns false on failure: if either argument is nullptr, or if the
// pixels can not be retrieved from the canvas. In the latter case resets
// the pixmap to empty.
SK_API bool GetWritablePixels(SkCanvas* canvas, SkPixmap* pixmap);
// Returns true if native platform routines can be used to draw on the
// given canvas. If this function returns false,
// ScopedPlatformPaint::GetPlatformSurface() should return NULL.
SK_API bool SupportsPlatformPaint(const SkCanvas* canvas);
// This object guards calls to platform drawing routines. The surface
// returned from GetPlatformSurface() can be used with the native platform
// routines.
class SK_API ScopedPlatformPaint {
public:
explicit ScopedPlatformPaint(SkCanvas* canvas);
// Returns the PlatformSurface to use for native platform drawing calls.
PlatformSurface GetPlatformSurface() { return platform_surface_; }
private:
SkCanvas* canvas_;
PlatformSurface platform_surface_;
// Disallow copy and assign
ScopedPlatformPaint(const ScopedPlatformPaint&);
ScopedPlatformPaint& operator=(const ScopedPlatformPaint&);
};
// Following routines are used in print preview workflow to mark the
// preview metafile.
SK_API SkMetaData& GetMetaData(const SkCanvas& canvas);
#if defined(OS_MACOSX)
SK_API void SetIsPreviewMetafile(const SkCanvas& canvas, bool is_preview);
SK_API bool IsPreviewMetafile(const SkCanvas& canvas);
// Returns the CGContext that backing the SkCanvas.
// Returns NULL if none is bound.
SK_API CGContextRef GetBitmapContext(const SkCanvas& canvas);
#endif
} // namespace skia
#endif // SKIA_EXT_PLATFORM_CANVAS_H_