Arjun PatelandGitHub
d6280439d0
* upload & view attachments to particles * allow download of attachments
25 lines
834 B
TypeScript
25 lines
834 B
TypeScript
/**
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* Downscale an image file to a thumbnail and return an object URL.
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* Returns undefined for non-image files.
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* Caller is responsible for revoking the URL via URL.revokeObjectURL().
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*/
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export async function createImageThumbnail(
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file: File,
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maxDim = 200,
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): Promise<string | undefined> {
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if (!file.type.startsWith("image/")) return undefined;
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const bitmap = await createImageBitmap(file);
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const scale = Math.min(1, maxDim / Math.max(bitmap.width, bitmap.height));
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const w = Math.round(bitmap.width * scale);
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const h = Math.round(bitmap.height * scale);
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const canvas = new OffscreenCanvas(w, h);
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const ctx = canvas.getContext("2d")!;
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ctx.drawImage(bitmap, 0, 0, w, h);
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bitmap.close();
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const blob = await canvas.convertToBlob({ type: "image/jpeg", quality: 0.7 });
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return URL.createObjectURL(blob);
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}
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