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nanot1m/setCanvasImageOpacity.ts

Created September 27, 2021 07:26
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Function to add opacity to the canvas image
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setCanvasImageOpacity.ts
function setCanvasImageOpacity(ctx: CanvasRenderingContext2D, opacity: number) {
const {width, height} = ctx.canvas
const image = ctx.getImageData(0, 0, width, height)
for (let i = 3; i < image.data.length; i += 4) {
image.data[i] *= opacity
}
ctx.putImageData(image, 0, 0)
}
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