tools/dom/templates/html/impl/impl_HTMLCanvasElement.darttemplate

// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

part of $LIBRARYNAME;

$(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS implements CanvasImageSource$IMPLEMENTS {
$!MEMBERS
  /** An API for drawing on this canvas. */
  CanvasRenderingContext2D get context2D =>
      JS('Null|CanvasRenderingContext2D', '#.getContext(#)', this, '2d');

  /**
   * Returns a new Web GL context for this canvas.
   *
   * ## Other resources
   *
   * * [WebGL fundamentals](http://www.html5rocks.com/en/tutorials/webgl/webgl_fundamentals/)
   *   from HTML5Rocks.
   * * [WebGL homepage](http://get.webgl.org/).
   */
  @SupportedBrowser(SupportedBrowser.CHROME)
  @SupportedBrowser(SupportedBrowser.FIREFOX)
  gl.RenderingContext$NULLABLE getContext3d({alpha: true, depth: true, stencil: false,
    antialias: true, premultipliedAlpha: true, preserveDrawingBuffer: false}) {

    var options = {
      'alpha': alpha,
      'depth': depth,
      'stencil': stencil,
      'antialias': antialias,
      'premultipliedAlpha': premultipliedAlpha,
      'preserveDrawingBuffer': preserveDrawingBuffer,
    };
    var context = getContext('webgl', options);
    if (context == null) {
      context = getContext('experimental-webgl', options);
    }
    return context $#NULLSAFECAST(as gl.RenderingContext$NULLABLE);
  }

  /**
   * Returns a data URI containing a representation of the image in the
   * format specified by type (defaults to 'image/png').
   *
   * Data Uri format is as follow
   * `data:[<MIME-type>][;charset=<encoding>][;base64],<data>`
   *
   * Optional parameter [quality] in the range of 0.0 and 1.0 can be used when
   * requesting [type] 'image/jpeg' or 'image/webp'. If [quality] is not passed
   * the default value is used. Note: the default value varies by browser.
   *
   * If the height or width of this canvas element is 0, then 'data:' is
   * returned, representing no data.
   *
   * If the type requested is not 'image/png', and the returned value is
   * 'data:image/png', then the requested type is not supported.
   *
   * Example usage:
   *
   *     CanvasElement canvas = new CanvasElement();
   *     var ctx = canvas.context2D
   *     ..fillStyle = "rgb(200,0,0)"
   *     ..fillRect(10, 10, 55, 50);
   *     var dataUrl = canvas.toDataUrl("image/jpeg", 0.95);
   *     // The Data Uri would look similar to
   *     // 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUA
   *     // AAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO
   *     // 9TXL0Y4OHwAAAABJRU5ErkJggg=='
   *     //Create a new image element from the data URI.
   *     var img = new ImageElement();
   *     img.src = dataUrl;
   *     document.body.children.add(img);
   *
   * See also:
   *
   * * [Data URI Scheme](http://en.wikipedia.org/wiki/Data_URI_scheme) from Wikipedia.
   *
   * * [HTMLCanvasElement](https://developer.mozilla.org/en-US/docs/DOM/HTMLCanvasElement) from MDN.
   *
   * * [toDataUrl](http://dev.w3.org/html5/spec/the-canvas-element.html#dom-canvas-todataurl) from W3C.
   */
  String toDataUrl([String type = 'image/png', num$NULLABLE quality]) =>
      _toDataUrl(type, quality);

  @JSName('toBlob')
  void _toBlob(BlobCallback callback, [String$NULLABLE type,
      Object$NULLABLE arguments]) native;

  Future<Blob> toBlob([String$NULLABLE type, Object$NULLABLE arguments]) {
    var completer = new Completer<Blob>();
      _toBlob((value) {
        completer.complete(value);
      }, type, arguments);
    return completer.future;
  }
}