Hooray, I did do some coding again for a change! One of the issues I had with submitting apps for the Firefox Marketplace is that the validator of the manifest always complains about me missing out on certain icon sizes. That’s why I thought it’d be sweet to have an in-browser tool to generate all of the icons one needs from an image. And here it is:

• The Icons Generator
• The Source

You can see a demo of it working on YouTube:

That’s all there is to it – it uses Canvas and the fileReader API to convert the images and create the files. JSZip, a neato library to create Zips was also in use.

For now your original image needs to be square and 512x512 pixels or the generator will just paste the first 512x512 pixels in. Images are automatically resized to 512 pixels and centered on a transparent background. A later version might allow you to move the image around. Let’s see when I get the time.

http://christianheilmann.com/2014/08/15/creating-a-set-of-icons-in-various-sizes-in-the-browser/