Question

5

Stream canvas to imgITools to make ico

rated 0 times [ 8] [ 3] / answers: 1 / hits: 16929 / 10 Years ago, mon, june 16, 2014, 12:00:00

So on WinXP I have been having a hard time converting a PNG file to an ICO with canvas. I found this method encodeImage. I don't know if it works but it looks promising but I can't figure out how to feed the image I drew on a canvas into imgITools.decodeData.

What should I use for aImageStream and/or aMimeType?

imgTools.decodeImageData(aImageStream, aMimeType, imgContainer);

This is more of my code:

 img['asdf'].file = new FileUtils.File(myPathHere);



let iconStream;

try {

  let imgTools = Cc[@mozilla.org/image/tools;1]

                    .createInstance(Ci.imgITools);

  let imgContainer = { value: null };



  imgTools.decodeImageData(aImageStream, aMimeType, imgContainer);

  iconStream = imgTools.encodeImage(imgContainer.value,

                                    image/vnd.microsoft.icon,

                                    format=bmp;bpp=32);

} catch (e) {

  alert('failure converting icon ' + e)

  throw(processIcon - Failure converting icon ( + e + ));

}



let outputStream = FileUtils.openSafeFileOutputStream(img['asdf'].file);

NetUtil.asyncCopy(iconStream, outStream, netutilCallback);

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kentrelle

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4 Years ago

answered 10 Years ago harleyaleenag · Accepted Answer

Since you're having a canvas already(?), it would be probably easier to use either on of the following canvas methods:

toDataURI/toDataURIHD

toBlob/toBlobHD

mozFetchAsStream

There is also the undocumented -moz-parse-options:, e.g -moz-parse-options:format=bmp;bpp=32. (ref-tests seem to depend on it, so it isn't going away anytime soon I'd think).

So, here is an example for loading stuff into an ArrayBuffer.

(canvas.toBlobHD || canvas.toBlob).call(canvas, function (b) {

    var r = new FileReader();

    r.onloadend = function () {

        // r.result contains the ArrayBuffer.

    };

    r.readAsArrayBuffer(b);

}, image/vnd.microsoft.icon, -moz-parse-options:format=bmp;bpp=32);

Here is a more complete example fiddle creating a 256x256 BMP icon.

Since you likely want to feed that data into js-ctypes, having an ArrayBuffer is great because you can create pointers from it directly, or write it to a file using OS.File.