Canvas Pixel Manipulation (v151)

Revision 151 of this benchmark created on

Description

Tests two different methods of manipulating pixels using the canvas.

Preparation HTML

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

Setup

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);

Teardown


    ctx.putImageData(imageData, 0, 0);

Test runner

Ready to run.

Testing in
TestOps/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
    }
}
ready
32-bit Pixel Manipulation
for (var y = 0; y < canvasHeight; ++y) {
    for (var x = 0; x < canvasWidth; ++x) {
        var value = x * y & 0xff;

        data32[y * canvasWidth + x] =
            (255   << 24) |    // alpha
            (value << 16) |    // blue
            (value <<  8) |    // green
             value;            // red
    }
}

imageData.data.set(buf8);
ready
Pixel cached data
var pixel = data[(300 * canvasWidth + 300) * 4]
ready
Pixel new data
var pixel = ctx.getImageData(300, 300, 1, 1).data;
ready

Revisions

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