gecko-dev/image/imgIEncoder.idl

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * 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 "nsISupports.idl"
#include "nsIAsyncInputStream.idl"
#include "nsIEventTarget.idl"

/**
 * imgIEncoder interface
 */
[scriptable, uuid(4baa2d6e-fee7-42df-ae3f-5fbebc0c267c)]
interface imgIEncoder : nsIAsyncInputStream
{
  // Possible values for outputOptions. Multiple values are semicolon-separated.
  //
  // PNG:
  // ----
  // transparency=[yes|no|none]  --  default: "yes"
  //     Overrides default from input format. "no" and "none" are equivalent.
  //
  //
  // APNG:
  // -----
  // The following options can be used with startImageEncode():
  //
  // transparency=[yes|no|none]  --  default: "yes"
  //     Overrides default from input format. "no" and "none" are equivalent.
  // skipfirstframe=[yes|no]  --  default: "no"
  //     Controls display of the first frame in animations. PNG-only clients
  //     always display the first frame (and only that frame).
  // frames=#  --  default: "1"
  //     Total number of frames in the image. The first frame, even if skipped,
  //     is always included in the count.
  // plays=#  --  default: "0"
  //     Number of times to play the animation sequence. "0" will repeat
  //     forever.
  //
  // The following options can be used for each frame, with addImageFrame():
  //
  // transparency=[yes|no|none]  --  default: "yes"
  //     Overrides default from input format. "no" and "none" are equivalent.
  // delay=#  --  default: "500"
  //     Number of milliseconds to display the frame, before moving to the next
  //     frame.
  // dispose=[none|background|previous]  --  default: "none"
  //     What to do with the image's canvas before rendering the next frame.
  //     See APNG spec.
  // blend=[source|over]  --  default: "source"
  //     How to render the new frame on the canvas. See APNG spec.
  // xoffset=#  --  default: "0"
  // yoffset=#  --  default: "0"
  //     Where to draw the frame, relative to the canvas.
  //
  //
  // JPEG:
  // -----
  //
  // quality=#  --  default: "92"
  //    Quality of compression, 0-100 (worst-best).
  //    Quality >= 90 prevents down-sampling of the color channels.


  // Possible values for input format (note that not all image formats
  // support saving alpha channels):

    // Input is RGB each pixel is represented by three bytes:
    // R, G, and B (in that order, regardless of host endianness)
  const uint32_t INPUT_FORMAT_RGB = 0;

    // Input is RGB each pixel is represented by four bytes:
    // R, G, and B (in that order, regardless of host endianness).
    // POST-MULTIPLIED alpha us used (50% transparent red is 0xff000080)
  const uint32_t INPUT_FORMAT_RGBA = 1;

    // Input is host-endian ARGB: On big-endian machines each pixel is therefore
    // ARGB, and for little-endian machiens (Intel) each pixel is BGRA
    // (This is used by canvas to match it's internal representation)
    //
    // PRE-MULTIPLIED alpha is used (That is, 50% transparent red is 0x80800000,
    // not 0x80ff0000
  const uint32_t INPUT_FORMAT_HOSTARGB = 2;

  /* data - list of bytes in the format specified by inputFormat
   * width  - width in pixels
   * height - height in pixels
   * stride - number of bytes per row in the image
   *          Normally (width*3) or (width*4), depending on your input format,
   *          but some data uses padding at the end of each row, which would
   *          be extra.
   * inputFormat - one of INPUT_FORMAT_* specifying the format of data
   * outputOptions - semicolon-delimited list of name=value pairs that can
   *                 give options to the output encoder. Options are encoder-
   *                 specific. Just give empty string for default behavior.
   */
  void initFromData([array, size_is(length), const] in uint8_t data,
                    in unsigned long length,
                    in uint32_t width,
                    in uint32_t height,
                    in uint32_t stride,
                    in uint32_t inputFormat,
                    in AString outputOptions);

  /*
   * For encoding images which may contain multiple frames, the 1-shot
   * initFromData() interface is too simplistic. The alternative is to
   * use startImageEncode(), call addImageFrame() one or more times, and
   * then finish initialization with endImageEncode().
   *
   * The arguments are basically the same as in initFromData().
   */
  void startImageEncode(in uint32_t width,
                    in uint32_t height,
                    in uint32_t inputFormat,
                    in AString outputOptions);

  void addImageFrame( [array, size_is(length), const] in uint8_t data,
                    in unsigned long length,
                    in uint32_t width,
                    in uint32_t height,
                    in uint32_t stride,
                    in uint32_t frameFormat,
                    in AString frameOptions);

  void endImageEncode();

  /*
   * Sometimes an encoder can contain another encoder and direct access
   * to its buffer is necessary.   It is only safe to assume that the buffer
   * returned from getImageBuffer() is of size equal to getImageBufferUsed().
   */
  [noscript] unsigned long getImageBufferUsed();
  [noscript] charPtr getImageBuffer();
};