Canvas Pixel Manipulation

JavaScript performance comparison

Revision 116 of this test case created by ass

Preparation code 

<canvas id="canvas" height="600" width="600"></canvas>
      

      <script>

        Benchmark.prototype.setup = function() {

          
  var canvas = document.getElementById('canvas');
  var canvasWidth  = canvas.width;
  var canvasHeight = canvas.height;
  var ctx = canvas.getContext('2d');
  var imageData = ctx.getImageData(0, 0, canvasWidth, canvasHeight);
  
  var data = imageData.data;
  
  
  var buf = new ArrayBuffer(imageData.data.length);
  var buf8 = new Uint8ClampedArray(buf);
  var data32 = new Uint32Array(buf);

        
  };
          



        Benchmark.prototype.teardown = function() {

          
  ctx.putImageData(imageData, 0, 0);

        
  };

      
</script>

Preparation code output

<canvas id="canvas" height="600" width="600"></canvas>

Test runner

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
8-bit Pixel Manipulation 
for (var y = 0; y < canvasHeight; ++y) {
    for (var x = 0; x < canvasWidth; ++x) {
        var index = (y * canvasWidth + x) * 4;

        var value = x * y & 0xff;

        data[index]   = value;    // red
        data[++index] = value;    // green
        data[++index] = value;    // blue
        data[++index] = 255;      // alpha
    }
}
 pending…
32-bit Pixel Manipulation 
var index = 0;
for (var y = 0; y < canvasHeight; ++y) {
    for (var x = 0; x < canvasWidth; ++x, index += 4) {
        var value = x * y & 0xff;

        data32[index] =
            (255   << 24) |    // alpha
            (value << 16) |    // blue
            (value <<  8) |    // green
             value;            // red
    }
}

imageData.data.set(buf8);
 pending…

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