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I added the experimental folder to show some work on filters that
can be applied to an entire layer. Multiple filters can be applied
to a layer (in any order, multiple times). To hook into the layer I
use:
layer.on('draw', filterFunc);
Eventually, I would like to move that to `layer.filterFunc` and
automatically apply it after the draw. `filterFunc` looks like:
function filterFunc(){
// Get pixel data and create a temporary pixel buffer for working
var imageData = this.getContext().getImageData(0,0,this.getCanvas().width,this.getCanvas().height);
var scratchData = this.getContext().createImageData(imageData);
// Apply all filters here
ColorStretch(imageData,scratchData,{});
// Copy the pixel data back
this.getContext().putImageData(scratchData,0,0);
}
`ColorStretch` is an example of a filter. It takes 3 arguments: the
original image data, image data to write the result to, and an options
object.
17 lines
537 B
JavaScript
17 lines
537 B
JavaScript
Grayscale = (function () {
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var Grayscale = function (src, dst) {
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var srcPixels = src.data,
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dstPixels = dst.data,
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nPixels = srcPixels.length,
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i, brightness;
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for (i = 0; i < nPixels; i += 4) {
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brightness = 0.34 * srcPixels[i] + 0.5 * srcPixels[i + 1] + 0.16 * srcPixels[i + 2];
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dstPixels[i] = brightness; // r
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dstPixels[i + 1] = brightness; // g
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dstPixels[i + 2] = brightness; // b
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dstPixels[i + 3] = srcPixels[i + 3]; // alpha
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}
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};
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return Grayscale;
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})();
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