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@fi-tomek-augustyn
Created October 29, 2012 09:51
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Transparent canvas fader
/**
* Fade transparent canvas using 'destination-out' mode.
* To avoid visible trails call
* fadeCanvas(canvas, 0.4, 'source-over');
*
* @param {element} canvas Reference to a Canvas DOM element
* @param {number} alpha Alpha percentage of how much to fade
* @param {string} mode Fading mode
*/
function fadeCanvas(canvas, alpha, mode) {
mode = mode || 'destination-out';
ctx = canvas.getContext('2d');
ctx.globalCompositeOperation = mode;
ctx.fillStyle = "rgba(255, 255, 255, " + alpha + ")";
ctx.beginPath();
ctx.fillRect(0, 0, canvas.width, canvas.height);
ctx.fill();
ctx.globalCompositeOperation = 'source-over';
}
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