description

# toDataUrl method Null safety

String toDataUrl (

1. [String type = 'image/png',
2. num? quality]

)

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 from Wikipedia.

- HTMLCanvasElement from MDN.

- toDataUrl from W3C.

## Implementation

    String toDataUrl([String type = 'image/png', num? quality]) =>
        _toDataUrl(type, quality);