blob: ff29b8622c6c49b0d4e5c10f57d95dc83523ead3 [file] [log] [blame]
// Copyright (c) 2012 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.
#include <stddef.h>
#include <memory>
#include "base/macros.h"
#include "base/memory/shared_memory_mapping.h"
#include "base/memory/unsafe_shared_memory_region.h"
#include "build/build_config.h"
#include "ui/surface/surface_export.h"
class SkCanvas;
// -----------------------------------------------------------------------------
// A TransportDIB is a block of memory that is used to transport pixels
// between processes: from the renderer process to the browser, and
// between renderer and plugin processes.
// -----------------------------------------------------------------------------
class SURFACE_EXPORT TransportDIB {
// Creates and maps a new TransportDIB with a shared memory region.
// Returns nullptr on failure.
static std::unique_ptr<TransportDIB> Map(
base::UnsafeSharedMemoryRegion region);
// Creates a new TransportDIB with a shared memory region. This always returns
// a valid pointer. The DIB is not mapped.
static std::unique_ptr<TransportDIB> CreateWithHandle(
base::UnsafeSharedMemoryRegion region);
// Returns a canvas using the memory of this TransportDIB. The returned
// pointer will be owned by the caller. The bitmap will be of the given size,
// which should fit inside this memory. Bitmaps returned will be either
// opaque or have premultiplied alpha.
// On POSIX, this |TransportDIB| will be mapped if not already. On Windows,
// this |TransportDIB| will NOT be mapped and should not be mapped prior,
// because PlatformCanvas will map the file internally.
// Will return NULL on allocation failure. This could be because the image
// is too large to map into the current process' address space.
std::unique_ptr<SkCanvas> GetPlatformCanvas(int w, int h, bool opaque);
// Map the DIB into the current process if it is not already. This is used to
// map a DIB that has already been created. Returns true if the DIB is mapped.
bool Map();
// Return a pointer to the shared memory.
void* memory() const;
// Return the maximum size of the shared memory. This is not the amount of
// data which is valid, you have to know that via other means, this is simply
// the maximum amount that /could/ be valid.
size_t size() const { return size_; }
// Returns a pointer to the UnsafeSharedMemoryRegion object that backs the
// transport dib.
base::UnsafeSharedMemoryRegion* shared_memory_region();
// Verifies that the dib can hold a canvas of the requested dimensions.
bool VerifyCanvasSize(int w, int h);
explicit TransportDIB(base::UnsafeSharedMemoryRegion region);
base::UnsafeSharedMemoryRegion shm_region_;
base::WritableSharedMemoryMapping shm_mapping_;
size_t size_ = 0;