117 lines
3.0 KiB
TypeScript
117 lines
3.0 KiB
TypeScript
const IMAGE_PROXY_PATH = "/api/image-proxy";
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type ImageProxyFormat = "webp" | "avif" | "jpeg" | "png";
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export type ImageProxyOptions = {
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width?: number;
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quality?: number;
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format?: ImageProxyFormat;
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delivery?: "display" | "proxy";
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};
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function clamp(value: number, min: number, max: number): number {
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return Math.max(min, Math.min(max, value));
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}
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function normalizeWidth(width?: number): number | undefined {
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if (!Number.isFinite(width) || !width) return undefined;
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return clamp(Math.round(width), 64, 4096);
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}
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function normalizeQuality(quality?: number): number | undefined {
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if (!Number.isFinite(quality) || !quality) return undefined;
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return clamp(Math.round(quality), 40, 100);
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}
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function isAbsoluteHttpUrl(url: string): boolean {
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return /^https?:\/\//i.test(url);
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}
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function isBypassUrl(url: string): boolean {
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return (
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!url ||
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url.startsWith("data:") ||
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url.startsWith("blob:") ||
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url.startsWith(IMAGE_PROXY_PATH) ||
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!isAbsoluteHttpUrl(url)
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);
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}
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function isAliyunOssImageHost(hostname: string): boolean {
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const normalized = hostname.trim().toLowerCase();
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return normalized.endsWith(".aliyuncs.com") && normalized.includes(".oss-");
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}
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function resolveAliyunOssDisplayUrl(
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url: string,
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options: Pick<ImageProxyOptions, "width" | "quality" | "format">
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): string | null {
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let target: URL;
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try {
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target = new URL(url);
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} catch {
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return null;
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}
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if (!isAliyunOssImageHost(target.hostname)) {
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return null;
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}
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if (target.searchParams.has("x-oss-process")) {
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return target.toString();
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}
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const width = normalizeWidth(options.width);
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const quality = normalizeQuality(options.quality);
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const format = options.format;
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if (!width && !quality && !format) {
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return target.toString();
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}
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const processSteps = ["image"];
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if (width) {
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processSteps.push(`resize,w_${width}`);
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}
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if (quality) {
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processSteps.push(`quality,q_${quality}`);
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}
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if (format) {
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const ossFormat = format === "jpeg" ? "jpg" : format;
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if (ossFormat !== "webp" && ossFormat !== "jpg" && ossFormat !== "png") {
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return null;
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}
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processSteps.push(`format,${ossFormat}`);
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}
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target.searchParams.set("x-oss-process", processSteps.join("/"));
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return target.toString();
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}
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export function buildImageProxyUrl(url: string, options: ImageProxyOptions = {}): string {
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const source = String(url || "").trim();
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if (isBypassUrl(source)) {
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return source;
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}
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if (options.delivery !== "proxy") {
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const directDisplayUrl = resolveAliyunOssDisplayUrl(source, options);
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if (directDisplayUrl) {
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return directDisplayUrl;
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}
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return source;
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}
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const width = normalizeWidth(options.width);
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const quality = normalizeQuality(options.quality);
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const format = options.format;
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const params = new URLSearchParams();
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params.set("url", source);
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if (width) params.set("w", String(width));
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if (quality) params.set("q", String(quality));
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if (format) params.set("f", format);
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return `${IMAGE_PROXY_PATH}?${params.toString()}`;
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}
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