expose ImageData constructor

[targos]

I need the ImageData constructor and I currently have to get it with require('canvas/lib/bindings').ImageData

Example use: convert a pixel array to dataURL

function toDataURL(width, height, pixels) {
    var imgData = new ImageData(pixels, width, height);
    var canvas = new Canvas(width, height);
    var ctx = canvas.getContext('2d');
    ctx.putImageData(imgData, 0, 0);
    return canvas.toDataURL();
}

[kangax]

+1 from me, but we should add it to documentation too then.

[targos]

I will investigate further because it only works with the internal CanvasPixelArray objects.
new ImageData(new Uint8ClampedArray(4), 1, 1) fails

[eqyiel]

I also need the ImageData constructor.

The line @targos posted not fail since #604 (now that ImageData is using Uint8ClampedArray). Can we get this merged?

[LinusU]

@targos Could you rebase on master? Also, adding documentation and tests will greatly increase the chances of this getting merged.

[targos]

I just found that the constructor does not behave correctly. For example, new ImageData(2, 2) creates an array with 4 elements when it should be 16 (width * height * 4)
I will try to fix that and add tests.

[zbjornson]

@targos my mistake (never tested those since they weren't exposed). Let me know if you want help or want me to fix it. I'm going to change that area soon for #637.

[targos]

I pushed an update to ImageData.cc + tests. PTAL
For the error messages, I copied the output from Chrome.

[zbjornson]

Looks good!

[LinusU]

You don't need else here, please change to

}
if (size % width != 0) {

[LinusU]

One small nit and if you could please rebase on master again (sorry), we have updated the travis config and it will ensure that your tests runs with our new config. Thank you!

[targos]

@LinusU done :)

[LinusU]

Cool! Merging now 👍

[LinusU]

Released as 1.3.0 \o/

[targos]

Thank you!