🎉 完成

init.go

@@ -0,0 +1,19 @@
+package imgsz
+
+import "io"
+
+func init() {
+	RegisterFormat("jpeg", "\xff\xd8", func(r io.Reader) (Size, error) {
+		var d jpgdecoder
+		return d.decode(r)
+	})
+	RegisterFormat("png", pngHeader, decodepng)
+	RegisterFormat("gif", "GIF8?a", func(r io.Reader) (Size, error) {
+		var d gifdecoder
+		if err := d.readHeaderAndScreenDescriptor(r); err != nil {
+			return Size{}, err
+		}
+		return Size{d.width, d.height}, nil
+	})
+	RegisterFormat("webp", "RIFF????WEBPVP8", decodewebp)
+}