[devdocsgjs/main: 887/1867] Add transparent background to doc icon on favicon

[Andy Holmes <andyholmes src gnome org>]

commit 6efad323ff55edd81e72a699f55ae5e4d7c80c73
Author: Jasper van Merle <jaspervmerle gmail com>
Date:   Sat Aug 24 01:06:50 2019 +0200

    Add transparent background to doc icon on favicon

 assets/javascripts/lib/favicon.coffee | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/assets/javascripts/lib/favicon.coffee b/assets/javascripts/lib/favicon.coffee
index 2f2d9f93..c2da3300 100644
--- a/assets/javascripts/lib/favicon.coffee
+++ b/assets/javascripts/lib/favicon.coffee
@@ -49,6 +49,12 @@ withImage = (url, action) ->
       docIconPercentage = 65
       destinationCoords = size / 100 * (100 - docIconPercentage)
       destinationSize = size / 100 * docIconPercentage
+      paddingSize = destinationSize + 1
+
+      imageData = ctx.getImageData(destinationCoords, destinationCoords, paddingSize, paddingSize)
+      transparentImageData = new ImageData(new Uint8ClampedArray(imageData.data.length), paddingSize, 
paddingSize)
+      ctx.putImageData(transparentImageData, destinationCoords, destinationCoords)
+
       ctx.drawImage(docImg, sourceX, sourceY, sourceSize, sourceSize, destinationCoords, destinationCoords, 
destinationSize, destinationSize)
 
       urlCache[doc.slug] = canvas.toDataURL()