Add thumbnail support via ffmpeg API (incomplete

thumbnail/ffmpeg_api.ts

@@ -0,0 +1,68 @@
+/// <reference lib="deno.unstable" />
+import { Struct } from "pwn/mod.ts";
+import { ThumbnailGenMethod } from "./base.ts";
+
+let libSuffix = "";
+let libPrefix = "lib";
+switch (Deno.build.os) {
+    case "windows":
+        libSuffix = "dll";
+        libPrefix = "";
+        break;
+    case "darwin":
+        libSuffix = "dylib";
+        break;
+    default:
+        libSuffix = "so";
+        break;
+}
+
+let libPath = import.meta.resolve(`../lib/${libPrefix}thumbnail.${libSuffix}`)
+    .slice(7);
+if (Deno.build.os === "windows") {
+    libPath = libPath.slice(1);
+}
+
+const lib = Deno.dlopen(
+    libPath,
+    {
+        "gen_thumbnail": {
+            "parameters": ["buffer", "buffer", "i32", "i32", "i32"],
+            "result": { struct: ["i32", "i32"] },
+            "nonblocking": true,
+        },
+        "thumbnail_error": {
+            "parameters": [{ struct: ["i32", "i32"] }, "buffer", "usize"],
+            "result": "void",
+        },
+    } as const,
+);
+const _Result = new Struct({ e: "s32", fferr: "s32" });
+
+function get_error(fferr: Uint8Array) {
+    const u = new Uint8Array(64);
+    lib.symbols.thumbnail_error(fferr, u, u.length);
+    let len = u.findIndex((i) => i === 0);
+    if (len === -1) len = u.length;
+    return (new TextDecoder()).decode(u.slice(0, len));
+}
+
+export async function gen_thumbnail(
+    src: string,
+    dest: string,
+    width: number,
+    height: number,
+    method: ThumbnailGenMethod,
+) {
+    const t = new TextEncoder();
+    const ore = await lib.symbols.gen_thumbnail(
+        t.encode(`${src}\0`),
+        t.encode(`${dest}\0`),
+        width,
+        height,
+        method,
+    );
+    const re = _Result.unpack(ore);
+    if (re.e) return get_error(ore);
+    return;
+}