text: // 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 "ui/surface/transport_dib.h"
  
  #include <windows.h>
  #include <stddef.h>
  #include <stdint.h>
  
  #include <limits>
  
  #include "base/logging.h"
  #include "base/memory/scoped_ptr.h"
  #include "base/sys_info.h"
  #include "skia/ext/platform_canvas.h"
  
  TransportDIB::TransportDIB()
      : size_(0) {
  }
  
  TransportDIB::~TransportDIB() {
  }
  
  TransportDIB::TransportDIB(base::SharedMemoryHandle handle)
      : shared_memory_(handle, false /* read write */), size_(0) {}
  
  // static
  TransportDIB* TransportDIB::Create(size_t size, uint32_t sequence_num) {
    TransportDIB* dib = new TransportDIB;
  
    if (!dib->shared_memory_.CreateAnonymous(size)) {
      delete dib;
      return NULL;
    }
  
    dib->size_ = size;
    dib->sequence_num_ = sequence_num;
  
    return dib;
  }
  
  // static
  TransportDIB* TransportDIB::Map(Handle handle) {
    scoped_ptr<TransportDIB> dib(CreateWithHandle(handle));
    if (!dib->Map())
      return NULL;
    return dib.release();
  }
  
  // static
  TransportDIB* TransportDIB::CreateWithHandle(Handle handle) {
    return new TransportDIB(handle);
  }
  
  // static
  bool TransportDIB::is_valid_handle(Handle dib) {
    return dib.IsValid();
  }
  
  skia::PlatformCanvas* TransportDIB::GetPlatformCanvas(int w, int h,
                                                        bool opaque) {
    // This DIB already mapped the file into this process, but PlatformCanvas
    // will map it again.
    DCHECK(!memory()) << "Mapped file twice in the same process.";
  
    // We can't check the canvas size before mapping, but it's safe because
    // Windows will fail to map the section if the dimensions of the canvas
    // are too large.
    skia::PlatformCanvas* canvas = skia::CreatePlatformCanvas(
        w, h, opaque, shared_memory_.handle().GetHandle(),
        skia::RETURN_NULL_ON_FAILURE);
  
    // Calculate the size for the memory region backing the canvas.
    if (canvas)
      size_ = skia::PlatformCanvasStrideForWidth(w) * h;
  
    return canvas;
  }
  
  bool TransportDIB::Map() {
    if (!is_valid_handle(shared_memory_.handle()))
      return false;
    if (memory())
      return true;
  
    if (!shared_memory_.Map(0 /* map whole shared memory segment */)) {
      LOG(ERROR) << "Failed to map transport DIB"
                 << " handle:" << shared_memory_.handle().GetHandle()
                 << " error:" << ::GetLastError();
      return false;
    }
  
    size_ = shared_memory_.mapped_size();
    return true;
  }
  
  void* TransportDIB::memory() const {
    return shared_memory_.memory();
  }
  