在worker中使用offscreenCanvas-白红宇

在worker中使用offscreenCanvas

阅读量：6264 次

发布时间：2019-06-22

本文共 1177 字，大约阅读时间需要 3 分钟。

HTML为

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>worker基本使用</title>
</head>
<body>
    <canvas id="myCanvas"></canvas>
    <button onclick="click()"></button>
</body>
<script>
  var offscreen = null;
  var worker = new Worker('offscreencanvas.js')
  function click () { 
      if(offscreen == null){ 
          var htmlCanvas = document.getElementById('myCanvas')
          offscreen = htmlCanvas.ControlToOffscreen()
      }
      worker.postMessage({ 
canvas:offscreen},[offscreen])
  }
</script>
</html>

Js代码为

var x = 50;
var y = 50;
var offCanvas = null;
onmessage = function(evt){ 
    if(offCanvas === null){ 
        offCanvas = evt.data.canvas
    } else{ 
        if(offCanvas == evt.data.canvas){ 
            console.log('offCanvas == evt.data.canvas')
        } else { 
            console.log('offCanvas != evt.data.canvas')
        }
    }
    gl = offCanvas.getContext('webgl');
    gl.viewport(0, gl.drawingBufferWidth, gl.drawingBufferHeight);
    gl.enable(gl.SCLSSOR_TEST);
    gl.scissor(y, x, 60, 60);
    gl.clearColor(1.0, 0.0, 0.0, 1.0)//red
    gl.clear(gl.COLOR_BUFFER_BIT)
    gl.commit()
    x +=10
    y += 10
}