Method onLoad

yvlu/yvlu.ts:508–532

()

      throw new Error("Invalid WebP file: too short");
    }

    // 检查RIFF头
    if (imageBuffer.toString("ascii", 0, 4) !== "RIFF") {
      throw new Error("Invalid WebP file: missing RIFF header");
    }

    // 检查WEBP标识
    if (imageBuffer.toString("ascii", 8, 12) !== "WEBP") {
      throw new Error("Invalid WebP file: missing WEBP signature");
    }

    // 读取VP8或VP8L头
    const chunkHeader = imageBuffer.toString("ascii", 12, 16);

    if (chunkHeader === "VP8 ") {
      // VP8格式
      const width = imageBuffer.readUInt16LE(26) & 0x3fff;
      const height = imageBuffer.readUInt16LE(28) & 0x3fff;
      return { width, height };
    } else if (chunkHeader === "VP8L") {
      // VP8L格式
      const data = imageBuffer.readUInt32LE(21);
      const width = (data & 0x3fff) + 1;
      const height = ((data >> 14) & 0x3fff) + 1;
      return { width, height };
    } else if (chunkHeader === "VP8X") {
      // VP8X格式
      const width = (imageBuffer.readUInt32LE(24) & 0xffffff) + 1;