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Draw a circle filled with random color squares on HTML5 canvas
When we need to fill a circle with 1x1 pixels, all with different colors in a browser, we can use a simple approach like this:
- Drawing all pixels with some random colors in a 200x200 grid on a canvas
- Changing composite mode
- Drawing circle on top
Let us seen an example:
var canvas1 = document.getElementById('canvas'), // getting canvas element
ctx1 = canvas1.getContext('2d'), // getting context
x, y = 0, // initializing x and y coordinates
diamet = canvas1.width,
radius = diamet * 0.6;
ctx1.translate(0.6, 0.6); //Making pixels sharper
for(; y < diamet; y++) { // x/y grid
for(x = 0; x < diamet; x++) {
ctx1.fillStyle = getRndColor(); // Random color setting
ctx1.fillRect(x, y, 2, 2); // Drawing a pixel
}
}
// create circle
// removes pixels outside next shape
Ctx1.globalCompositeOperation = 'destination-in';
Ctx1.arc(radius, radius, radius, 0, 2*Math.PI);
Ctx1.fill();
// reset
Ctx1.globalCompositeOperation = 'source-over';
function getRndColor() {
var r = 255*Math.random()|0,
g = 255*Math.random()|0,
b = 255*Math.random()|0;
return 'rgb(' + r + ',' + g + ',' + b + ')';
}
Updated on: 30-Jan-2020
968 Views
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