gecko-dev/image/ICOFileHeaders.h

/* 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/. */

#ifndef mozilla_image_ICOFileHeaders_h
#define mozilla_image_ICOFileHeaders_h

namespace mozilla {
namespace image {

#define ICONFILEHEADERSIZE 6
#define ICODIRENTRYSIZE 16
#define PNGSIGNATURESIZE 8
#define BMPFILEHEADERSIZE 14

/**
 * The header that comes right at the start of an icon file. (This
 * corresponds to the Windows ICONDIR structure.)
 */
struct IconFileHeader {
  /**
   * Must be set to 0;
   */
  uint16_t mReserved;
  /**
   * 1 for icon (.ICO) image (or 2 for cursor (.CUR) image (icon with the
   * addition of a hotspot), but we don't support cursor).
   */
  uint16_t mType;
  /**
   * The number of BMP/PNG images contained in the icon file.
   */
  uint16_t mCount;
};

/**
 * For each BMP/PNG image that the icon file contains there must be a
 * corresponding icon dir entry. (This corresponds to the Windows
 * ICONDIRENTRY structure.) These entries are encoded directly after the
 * IconFileHeader.
 */
struct IconDirEntry {
  uint8_t mWidth;
  uint8_t mHeight;
  /**
   * The number of colors in the color palette of the BMP/PNG that this dir
   * entry corresponds to, or 0 if the image does not use a color palette.
   */
  uint8_t mColorCount;
  /**
   * Should be set to 0.
   */
  uint8_t mReserved;
  union {
    uint16_t mPlanes;    // ICO
    uint16_t mXHotspot;  // CUR
  };
  union {
    uint16_t mBitCount;  // ICO (bits per pixel)
    uint16_t mYHotspot;  // CUR
  };
  /**
   * "bytes in resource" is the length of the encoded BMP/PNG that this dir
   * entry corresponds to.
   */
  uint32_t mBytesInRes;
  /**
   * The offset of the start of the encoded BMP/PNG that this dir entry
   * corresponds to (from the start of the icon file).
   */
  uint32_t mImageOffset;
};

}  // namespace image
}  // namespace mozilla

#endif  // mozilla_image_ICOFileHeaders_h