Created
November 20, 2023 08:57
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Draw canvas with path and backgroundSize(cover or percentage)
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function drawImage<Number extends number>({ | |
url, | |
width, | |
height, | |
path, | |
backgroundColor = 'transparent', | |
filter = 'none', | |
backgroundSize = 'cover' | |
}: { | |
url: string | |
width: number | |
height: number | |
path: string | |
backgroundColor?: string | |
filter?: string | |
backgroundSize?: 'cover' | `${Number}%` | |
}) { | |
const canvas = document.createElement('canvas') | |
canvas.width = width | |
canvas.height = height | |
const ctx = canvas.getContext('2d') | |
const clipPath = new Path2D(path) | |
ctx!.lineWidth = 6 | |
ctx!.lineCap = 'round' | |
ctx!.strokeStyle = '#4969aa' | |
ctx?.stroke(clipPath) | |
ctx!.fillStyle = backgroundColor | |
ctx?.fill(clipPath) | |
ctx?.clip(clipPath) | |
ctx!.filter = filter | |
const img = new Image() | |
img.src = url | |
img.onload = () => { | |
let ratio = Math.min(width / img.width, height / img.height) | |
let imgWidth = img.width * ratio | |
let imgHeight = img.height * ratio | |
let calcX = 1 | |
let calcY = 1 | |
let calcWidth = 1 | |
let calcHeight = 1 | |
if (backgroundSize === 'cover') { | |
let aspectRatio = 1 | |
// fill in the gaps | |
if (imgWidth < width) { | |
aspectRatio = width / imgWidth | |
} | |
if (Math.abs(aspectRatio - 1) < 1e-14 && imgHeight < height) { | |
aspectRatio = height / imgHeight | |
} | |
imgWidth *= aspectRatio | |
imgHeight *= aspectRatio | |
// calculate source rectangle | |
calcWidth = img.width / (imgWidth / width) | |
calcHeight = img.height / (imgHeight / height) | |
calcX = (img.width - calcWidth) * 0.5 | |
calcY = (img.height - calcHeight) * 0.5 | |
// make sure source rectangle is valid | |
if (calcX < 0) { | |
calcX = 0 | |
} | |
if (calcY < 0) { | |
calcY = 0 | |
} | |
if (calcWidth > img.width) { | |
calcWidth = img.width | |
} | |
if (calcHeight > img.height) { | |
calcHeight = img.height | |
} | |
console.log(calcX, calcY, calcWidth, calcHeight, width, height) | |
ctx?.drawImage( | |
img, | |
calcX, | |
calcY, | |
calcWidth, | |
calcHeight, | |
0, | |
0, | |
width, | |
height | |
) | |
} else if (backgroundSize.includes('%')) { | |
const scale = parseInt(backgroundSize.replace('%', ''), 10) / 100 | |
calcWidth = imgWidth * scale | |
calcHeight = imgHeight * scale | |
calcX = (width - calcWidth) / 2 | |
calcY = (height - calcHeight) / 2 | |
ctx?.drawImage(img, calcX, calcY, calcWidth, calcHeight) | |
} | |
console.log(canvas.toDataURL()) | |
} | |
} |
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