Automattic/node-canvas

Use standard Canvas `ctx.filter` API (blur/grayscale/saturate/contrast)

Open

#1,063 opened on Dec 21, 2017

View on GitHub
 (19 comments) (24 reactions) (0 assignees)JavaScript (9,524 stars) (1,140 forks)batch import
FeatureHelp wanted

Description

HTML5 Canvas recently introduced support for filters like ctx.filter = "blur(5px)"; in the browser, for example to blur, saturate, grayscale and modify contrast.

Issue or Feature

API support for HTML5 Canvas ctx.filter from from MDN web docs

Steps to Reproduce

var Canvas = require('canvas');
var canvas = Canvas.createCanvas(200, 200);
var ctx = canvas.getContext('2d');
ctx.filter = "blur(5px)";
ctx.drawImage(img,0,0);

Your Environment

  • node-canvas: 2.0.0 alpha
  • node: v9.3.0
  • macOS: High Sierra

Contributor guide

Tech stack
javascriptnodejs
Domain
api
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaScriptNode.jsCanvas APInode canvas
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Review the MDN documentation for the CanvasRenderingContext2D filter property. Examine the node canvas C++ binding in src/Canvas.cc and src/CanvasRenderingContext2D.cc to understand how other properties like shadowBlur are implemented. Look at previous attempts or discussions in the issue comments to identify challenges.