Automattic/node-canvas
Ver no GitHubIncorrect transparent GIF blending when it's transparent color is not black
Open
#116 aberto em 4 de set. de 2011
BugHelp wantedImages & Formats: GIF
Métricas do repositório
- Stars
- (9.524 stars)
- Métricas de merge de PR
- (Mesclagem média 34d 18h) (2 fundiu PRs em 30d)
Description
The value of the color marked as transparent is not discarded, but blended with background using "add" operation if the background isn't transparent.
For example, here is an image that is transparent, but the color of the transparent index in it's palette is set to #804000:
var assert = require('assert')
var Canvas = require('canvas')
var c = new Canvas(150, 150)
var ctx = c.getContext('2d')
// fill background with something non-transparent
ctx.fillStyle = 'rgb(0, 100, 200)'
ctx.fillRect(0, 0, 150, 150)
// load the (supposedly) transparent gif
var i = new Canvas.Image()
i.src = 'transparent.gif' // https://i.imgur.com/XCz0eVi.gif
// draw it on top of our background
ctx.drawImage(i, 0, 0)
// expect no visible change in the canvas
var pixel = ctx.getImageData(0, 0, 1, 1).data
assert.deepEqual(pixel, [0, 100, 200, 255])