GCanvas/node/examples/globalAlpha.js

33 lines
755 B
JavaScript

const { createCanvas, Image } = require('../export');
const canvas = createCanvas(150, 150)
const ctx = canvas.getContext('2d')
ctx.fillStyle = '#FD0'
ctx.fillRect(0, 0, 75, 75)
ctx.fillStyle = '#6C0'
ctx.fillRect(75, 0, 75, 75)
ctx.fillStyle = '#09F)'
ctx.fillRect(0, 75, 75, 75)
ctx.fillStyle = '#F30'
ctx.fillRect(75, 75, 150, 150)
ctx.fillStyle = '#FFF'
// set transparency value
ctx.globalAlpha = 0.2
// Draw semi transparent circles
for (var i = 0; i < 7; i++) {
ctx.beginPath()
ctx.arc(75, 75, 10 + 10 * i, 0, Math.PI * 2, true)
ctx.fill()
}
const fs = require('fs')
const path = require('path')
const out = fs.createWriteStream(path.join(__dirname, "..")+ '/globalAlpha.png');
var stream = canvas.createPNGStream();
stream.pipe(out);