SharedDIBWin.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "SharedDIBWin.h"
#include "gfxAlphaRecovery.h"
#include "nsMathUtils.h"
#include "nsDebug.h"

namespace mozilla {
namespace gfx {

static const uint32_t kByteAlign = 1 << gfxAlphaRecovery::GoodAlignmentLog2();
static const uint32_t kHeaderBytes =
    (uint32_t(sizeof(BITMAPV4HEADER)) + kByteAlign - 1) & ~(kByteAlign - 1);

SharedDIBWin::SharedDIBWin()
    : mSharedHdc(nullptr), mSharedBmp(nullptr), mOldObj(nullptr) {}

SharedDIBWin::~SharedDIBWin() { Close(); }

nsresult SharedDIBWin::Close() {
  if (mSharedHdc && mOldObj) ::SelectObject(mSharedHdc, mOldObj);

  if (mSharedHdc) ::DeleteObject(mSharedHdc);

  if (mSharedBmp) ::DeleteObject(mSharedBmp);

  mSharedHdc = nullptr;
  mOldObj = mSharedBmp = nullptr;

  SharedDIB::Close();

  return NS_OK;
}

nsresult SharedDIBWin::Create(HDC aHdc, uint32_t aWidth, uint32_t aHeight,
                              bool aTransparent) {
  Close();

  // create the offscreen shared dib
  BITMAPV4HEADER bmih;
  uint32_t size = SetupBitmapHeader(aWidth, aHeight, aTransparent, &bmih);

  nsresult rv = SharedDIB::Create(size);
  if (NS_FAILED(rv)) return rv;

  if (NS_FAILED(SetupSurface(aHdc, &bmih))) {
    Close();
    return NS_ERROR_FAILURE;
  }

  return NS_OK;
}

nsresult SharedDIBWin::Attach(Handle aHandle, uint32_t aWidth, uint32_t aHeight,
                              bool aTransparent) {
  Close();

  BITMAPV4HEADER bmih;
  SetupBitmapHeader(aWidth, aHeight, aTransparent, &bmih);

  nsresult rv = SharedDIB::Attach(aHandle, 0);
  if (NS_FAILED(rv)) return rv;

  if (NS_FAILED(SetupSurface(nullptr, &bmih))) {
    Close();
    return NS_ERROR_FAILURE;
  }

  return NS_OK;
}

uint32_t SharedDIBWin::SetupBitmapHeader(uint32_t aWidth, uint32_t aHeight,
                                         bool aTransparent,
                                         BITMAPV4HEADER* aHeader) {
  // D3D cannot handle an offscreen memory that pitch (SysMemPitch) is negative.
  // So we create top-to-bottom DIB.
  memset((void*)aHeader, 0, sizeof(BITMAPV4HEADER));
  aHeader->bV4Size = sizeof(BITMAPV4HEADER);
  aHeader->bV4Width = aWidth;
  aHeader->bV4Height = -LONG(aHeight);  // top-to-buttom DIB
  aHeader->bV4Planes = 1;
  aHeader->bV4BitCount = 32;
  aHeader->bV4V4Compression = BI_BITFIELDS;
  aHeader->bV4RedMask = 0x00FF0000;
  aHeader->bV4GreenMask = 0x0000FF00;
  aHeader->bV4BlueMask = 0x000000FF;

  if (aTransparent) aHeader->bV4AlphaMask = 0xFF000000;

  return (kHeaderBytes +
          (-aHeader->bV4Height * aHeader->bV4Width * kBytesPerPixel));
}

nsresult SharedDIBWin::SetupSurface(HDC aHdc, BITMAPV4HEADER* aHdr) {
  mSharedHdc = ::CreateCompatibleDC(aHdc);

  if (!mSharedHdc) return NS_ERROR_FAILURE;

  mSharedBmp =
      ::CreateDIBSection(mSharedHdc, (BITMAPINFO*)aHdr, DIB_RGB_COLORS,
                         &mBitmapBits, mShMem->GetHandle(), kHeaderBytes);
  if (!mSharedBmp) return NS_ERROR_FAILURE;

  mOldObj = SelectObject(mSharedHdc, mSharedBmp);

  return NS_OK;
}

}  // namespace gfx
}  // namespace mozilla