base/gfx/bitmap_header.cc

// Copyright 2008, Google Inc.
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#include "base/gfx/bitmap_header.h"

namespace gfx {

void CreateBitmapHeader(int width, int height, BITMAPINFOHEADER* hdr) {
  CreateBitmapHeaderWithColorDepth(width, height, 32, hdr);
}

void CreateBitmapHeaderWithColorDepth(int width, int height, int color_depth,
                                      BITMAPINFOHEADER* hdr) {
  // These values are shared with gfx::PlatformDevice
  hdr->biSize = sizeof(BITMAPINFOHEADER);
  hdr->biWidth = width;
  hdr->biHeight = -height;  // minus means top-down bitmap
  hdr->biPlanes = 1;
  hdr->biBitCount = color_depth;
  hdr->biCompression = BI_RGB;  // no compression
  hdr->biSizeImage = 0;
  hdr->biXPelsPerMeter = 1;
  hdr->biYPelsPerMeter = 1;
  hdr->biClrUsed = 0;
  hdr->biClrImportant = 0;
}


void CreateBitmapV4Header(int width, int height, BITMAPV4HEADER* hdr) {
  // Because bmp v4 header is just an extension, we just create a v3 header and
  // copy the bits over to the v4 header.
  BITMAPINFOHEADER header_v3;
  CreateBitmapHeader(width, height, &header_v3);
  memset(hdr, 0, sizeof(BITMAPV4HEADER));
  memcpy(hdr, &header_v3, sizeof(BITMAPINFOHEADER));

  // Correct the size of the header and fill in the mask values.
  hdr->bV4Size = sizeof(BITMAPV4HEADER);
  hdr->bV4RedMask   = 0x00ff0000;
  hdr->bV4GreenMask = 0x0000ff00;
  hdr->bV4BlueMask  = 0x000000ff;
  hdr->bV4AlphaMask = 0xff000000;
}

// Creates a monochrome bitmap header.
void CreateMonochromeBitmapHeader(int width,
                                  int height,
                                  BITMAPINFOHEADER* hdr) {
  hdr->biSize = sizeof(BITMAPINFOHEADER);
  hdr->biWidth = width;
  hdr->biHeight = -height;
  hdr->biPlanes = 1;
  hdr->biBitCount = 1;
  hdr->biCompression = BI_RGB;
  hdr->biSizeImage = 0;
  hdr->biXPelsPerMeter = 1;
  hdr->biYPelsPerMeter = 1;
  hdr->biClrUsed = 0;
  hdr->biClrImportant = 0;
}

}  // namespace gfx