HTMLCanvasElement.mozFetchAsStream() - Web APIs 编辑

Obsolete

This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

The HTMLCanvasElement.mozFetchAsStream() internal method used to create a new input stream that, when ready, would provide the contents of the canvas as image data. However, this non-standard and internal method has been removed.

Syntax

void canvas.mozFetchAsStream(callback, type);

Parameters

callback

An nsIInputStreamCallback.

type Optional

A DOMString indicating the image format. The default type is image/png.

Return value

None.

Examples

Save to disk with mozFetchAsStream (Chrome context only)

This technique also converts it to ico, however it will not work in Windows XP as WinXP cannot convert from PNG to ICO. It saves to the desktop it uses FileUtils.jsm. Also uses NetUtil.jsm

var canvas = document.getElementById('canvas');
var d = canvas.width;
ctx = canvas.getContext('2d');
ctx.beginPath();
ctx.moveTo(d / 2, 0);
ctx.lineTo(d, d);
ctx.lineTo(0, d);
ctx.closePath();
ctx.fillStyle = 'yellow';
ctx.fill();

var netutilCallback = function() {
    return function(result) {
       if (!Components.isSuccessCode(result)) {
          alert('FAILED to create icon');
       } else {
           alert('succesfully made');
       }
    };
}

var mfasCallback = function(iconName) {
    return function(inStream) {
       var file = FileUtils.getFile('Desk', [iconName + '.ico']);
       var outStream = FileUtils.openFileOutputStream(file);
       Cu.import('resource://gre/modules/NetUtil.jsm');
       NetUtil.asyncCopy(inStream, outStream, netutilCallback());
    }
}

canvas.mozFetchAsStream(mfasCallback('myIcon'), 'image/vnd.microsoft.icon');

Specifications

Not part of any specification.

Browser compatibility

BCD tables only load in the browser

See also

• The interface defining it, HTMLCanvasElement.