94 lines
4.7 KiB
TypeScript
94 lines
4.7 KiB
TypeScript
import { createFalClient } from "@fal-ai/client";
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import sharp from "sharp";
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export const FAL_OUTPAINT_MODEL = "fal-ai/flux-2-pro/outpaint";
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export function getOutpaintGeometry(width: number, height: number, xScale: number, yScale: number) {
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const targetWidth = Math.round(width * xScale);
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const targetHeight = Math.round(height * yScale);
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const ratio = Math.min(1, 2048 / Math.max(targetWidth, targetHeight));
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const modelWidth = Math.max(1, Math.floor(targetWidth * ratio));
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const modelHeight = Math.max(1, Math.floor(targetHeight * ratio));
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const sourceWidth = Math.max(1, Math.round(width * modelWidth / targetWidth));
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const sourceHeight = Math.max(1, Math.round(height * modelHeight / targetHeight));
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const left = Math.floor((targetWidth - width) / 2);
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const top = Math.floor((targetHeight - height) / 2);
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const modelLeft = Math.round(left * modelWidth / targetWidth);
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const modelTop = Math.round(top * modelHeight / targetHeight);
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// Align the model canvas to its 16-pixel grid, then remove the extra border.
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const extraWidth = (16 - modelWidth % 16) % 16;
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const extraHeight = (16 - modelHeight % 16) % 16;
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const cropLeft = Math.floor(extraWidth / 2);
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const cropTop = Math.floor(extraHeight / 2);
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return {
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targetWidth, targetHeight, left, top, modelWidth, modelHeight, sourceWidth, sourceHeight,
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paddedWidth: modelWidth + extraWidth,
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paddedHeight: modelHeight + extraHeight,
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cropLeft,
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cropTop,
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expandLeft: modelLeft + cropLeft,
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expandRight: modelWidth - sourceWidth - modelLeft + extraWidth - cropLeft,
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expandTop: modelTop + cropTop,
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expandBottom: modelHeight - sourceHeight - modelTop + extraHeight - cropTop,
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};
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}
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export async function composeOutpaint(source: Buffer, expanded: Buffer, geometry: ReturnType<typeof getOutpaintGeometry>) {
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const { targetWidth, targetHeight, left, top, modelWidth, modelHeight, paddedWidth, paddedHeight, cropLeft, cropTop } = geometry;
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const modelImage = sharp(expanded);
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const info = await modelImage.metadata();
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if (info.width !== paddedWidth || info.height !== paddedHeight) {
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throw new Error("扩图服务返回的图片尺寸不正确");
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}
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// Copy the source rectangle, including transparent pixels, without blending or resizing it.
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const { data: original, info: sourceInfo } = await sharp(source).toColourspace("srgb").ensureAlpha().raw().toBuffer({ resolveWithObject: true });
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const result = await modelImage
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.extract({ left: cropLeft, top: cropTop, width: modelWidth, height: modelHeight })
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.resize(targetWidth, targetHeight, { fit: "fill" })
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.toColourspace("srgb").ensureAlpha().raw().toBuffer();
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const stride = sourceInfo.width * 4;
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for (let row = 0; row < sourceInfo.height; row++) {
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original.copy(result, ((top + row) * targetWidth + left) * 4, row * stride, (row + 1) * stride);
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}
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return sharp(result, { raw: { width: targetWidth, height: targetHeight, channels: 4 } }).png().toBuffer();
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}
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export async function expandWithFalOutpaint({ imageUrl, apiKey, xScale, yScale }: {
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imageUrl: string;
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apiKey: string;
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xScale: number;
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yScale: number;
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}) {
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const response = await fetch(imageUrl, { signal: AbortSignal.timeout(45_000) });
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if (!response.ok) throw new Error("无法读取待扩展的原图");
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const { data: source, info } = await sharp(Buffer.from(await response.arrayBuffer()))
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.rotate().png().toBuffer({ resolveWithObject: true });
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const geometry = getOutpaintGeometry(info.width, info.height, xScale, yScale);
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if (geometry.targetWidth * geometry.targetHeight > 64_000_000) {
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throw new Error("扩图后的尺寸过大，请降低扩展倍数");
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}
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const fal = createFalClient({ credentials: apiKey });
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const modelSource = geometry.sourceWidth === info.width && geometry.sourceHeight === info.height
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? source
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: await sharp(source).resize(geometry.sourceWidth, geometry.sourceHeight, { fit: "fill" }).png().toBuffer();
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const image = await fal.storage.upload(new Blob([new Uint8Array(modelSource)], { type: "image/png" }));
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const { data } = await fal.subscribe(FAL_OUTPAINT_MODEL, {
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input: {
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image_url: image,
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expand_left: geometry.expandLeft,
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expand_right: geometry.expandRight,
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expand_top: geometry.expandTop,
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expand_bottom: geometry.expandBottom,
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mode: "high",
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output_format: "png",
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},
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timeout: 90_000,
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});
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const outputUrl = (data as { images?: Array<{ url?: string }> }).images?.[0]?.url;
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if (!outputUrl) throw new Error("扩图服务未返回图片");
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const output = await fetch(outputUrl, { signal: AbortSignal.timeout(25_000) });
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if (!output.ok) throw new Error("无法读取扩图结果");
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return composeOutpaint(source, Buffer.from(await output.arrayBuffer()), geometry);
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}
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