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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>
#include "build/build_config.h"
#if defined(OS_WIN)
#include <windows.h>
#endif
// The platform-specific device will include the necessary platform headers
// to get the surface type.
#include "third_party/skia/include/core/SkBitmap.h"
#include "third_party/skia/include/core/SkCanvas.h"
// 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 std::unique_ptr<SkCanvas> CreatePlatformCanvasWithSharedSection(
int width,
int height,
bool is_opaque,
HANDLE shared_section,
OnFailureType failure_type);
// Returns the NativeDrawingContext to use for native platform drawing calls.
SK_API HDC GetNativeDrawingContext(SkCanvas* canvas);
#elif defined(__linux__) || defined(__FreeBSD__) || defined(__OpenBSD__) || \
defined(__sun) || defined(ANDROID) || defined(__APPLE__) || \
defined(__Fuchsia__)
// 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 std::unique_ptr<SkCanvas> CreatePlatformCanvasWithPixels(
int width,
int height,
bool is_opaque,
uint8_t* data,
OnFailureType failure_type);
#endif
static inline std::unique_ptr<SkCanvas> CreatePlatformCanvas(int width,
int height,
bool is_opaque) {
#if defined(WIN32)
return CreatePlatformCanvasWithSharedSection(width, height, is_opaque, 0,
CRASH_ON_FAILURE);
#else
return CreatePlatformCanvasWithPixels(width, height, is_opaque, nullptr,
CRASH_ON_FAILURE);
#endif
}
static inline std::unique_ptr<SkCanvas> TryCreateBitmapCanvas(int width,
int height,
bool is_opaque) {
#if defined(WIN32)
return CreatePlatformCanvasWithSharedSection(width, height, is_opaque, 0,
RETURN_NULL_ON_FAILURE);
#else
return CreatePlatformCanvasWithPixels(width, height, is_opaque, nullptr,
RETURN_NULL_ON_FAILURE);
#endif
}
// 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);
} // namespace skia
#endif // SKIA_EXT_PLATFORM_CANVAS_H_
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