mirror of
https://github.com/NanmiCoder/cc-haha
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18 lines
949 B
TypeScript
18 lines
949 B
TypeScript
export function planResize(w: number, h: number, maxEdge: number): { width: number; height: number } {
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const longest = Math.max(w, h)
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if (longest <= maxEdge) return { width: w, height: h }
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const scale = maxEdge / longest
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return { width: Math.round(w * scale), height: Math.round(h * scale) }
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}
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/** 浏览器内：把 dataUrl 缩放到 maxEdge 内并以 quality 重新编码。 */
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export async function compressDataUrl(dataUrl: string, maxEdge = 1600, quality = 0.85): Promise<string> {
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const img = new Image()
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await new Promise<void>((res, rej) => { img.onload = () => res(); img.onerror = () => rej(new Error('load')); img.src = dataUrl })
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const { width, height } = planResize(img.naturalWidth, img.naturalHeight, maxEdge)
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const canvas = document.createElement('canvas')
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canvas.width = width; canvas.height = height
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canvas.getContext('2d')!.drawImage(img, 0, 0, width, height)
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return canvas.toDataURL('image/png', quality)
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}
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