javascript 将画布流式传输到 imgITools 以制作 ico
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/24251136/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Stream canvas to imgITools to make ico
提问by Noitidart
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.
因此，在 WinXP 上，我很难将 PNG 文件转换为带有画布的 ICO。我找到了这个方法encodeImage。我不知道它是否有效，但看起来很有希望，但我不知道如何将我在画布上绘制的图像输入imgITools.decodeData.
What should I use for aImageStreamand/or aMimeType?
我应该用什么aImageStream和/或aMimeType？
imgTools.decodeImageData(aImageStream, aMimeType, imgContainer);
This is more of my code:
这是我的更多代码：
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);
回答by nmaier
Since you're having a canvas already(?), it would be probably easier to use either on of the following canvas methods:
由于您已经有一个画布（？），使用以下任一画布方法可能会更容易：
toDataURI/toDataURIHDtoBlob/toBlobHDmozFetchAsStream
toDataURI/toDataURIHDtoBlob/toBlobHDmozFetchAsStream
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).
还有未记录的-moz-parse-options:，例如-moz-parse-options:format=bmp;bpp=32. （参考测试似乎取决于它，所以我认为它不会很快消失）。
So, here is an example for loading stuff into an ArrayBuffer.
因此，这是一个将内容加载到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 fiddlecreating a 256x256 BMP icon.
这是一个更完整的示例小提琴，可创建 256x256 BMP 图标。
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.
由于您可能希望将该数据提供给 js-ctypes，因此拥有 ArrayBuffer 非常棒，因为您可以直接从它创建指针，或使用OS.File.
