a little more flexibility with scaling images by url

media.go

@@ -66,6 +66,25 @@ func (ms *MediaSource) receiveNewMedia(name string, r io.Reader) error {
 type Media struct {
 	Type string
 	Name string
+	Size image.Rectangle
+}
+
+func (ms *MediaSource) Size(name string) (image.Rectangle, error) {
+	f, err := os.Open(name)
+	if err != nil {
+		return image.ZR, err
+	}
+	defer f.Close()
+
+	cfg, _, err := image.DecodeConfig(f)
+	if err != nil {
+		return image.ZR, err
+	}
+
+	width := cfg.Width
+	height := cfg.Height
+
+	return image.Rect(0, 0, width, height), nil
 }
 
 func (ms *MediaSource) ThumbMax(m Media, maxDim int) (string, image.Rectangle, error) {
@@ -116,9 +135,11 @@ func (ms *MediaSource) HasThumb(m Media, size image.Rectangle) bool {
 }
 
 func (ms *MediaSource) ByName(name string) *Media {
+	size, _ := ms.Size(path.Join(ms.StorageDir, name))
 	return &Media{
 		Type: "image",
 		Name: name,
+		Size: size,
 	}
 }
 
@@ -280,14 +301,14 @@ func (ch *CaddyHugo) serveMediaPage(w http.ResponseWriter, r *http.Request) (int
 }
 
 var (
-	sizeString = regexp.MustCompile(`([0-9]*)x([0-9]*)`)
+	sizeString = regexp.MustCompile(`([0-9]*)(x)?([0-9]*)`)
 )
 
-func parseSizeString(str string) (image.Rectangle, error) {
+func parseSizeString(str string, actual image.Rectangle) (image.Rectangle, error) {
 	var err = fmt.Errorf("expected a size string {width}x{height}, saw %q", str)
 
 	strs := sizeString.FindStringSubmatch(str)
-	if len(strs) < 3 {
+	if len(strs) < 4 {
 		return image.ZR, err
 	}
 
@@ -301,13 +322,25 @@ func parseSizeString(str string) (image.Rectangle, error) {
 		}
 	}
 
-	if strs[2] != "" {
-		h, strconvErr = strconv.Atoi(strs[2])
+	if strs[3] != "" {
+		h, strconvErr = strconv.Atoi(strs[3])
 		if strconvErr != nil {
 			return image.ZR, err
 		}
 	}
 
+	if strs[2] != "x" {
+		// w was the only dimension given, so set it to the greater dimension
+		// of the actual image size
+		if actual.Dx() > actual.Dy() {
+			w = w
+			h = 0
+		} else {
+			h = w
+			w = 0
+		}
+	}
+
 	return image.Rect(0, 0, w, h), nil
 }
 
@@ -326,7 +359,7 @@ func (ch *CaddyHugo) serveMedia(w http.ResponseWriter, r *http.Request) (int, er
 
 	if len(segs) >= 4 && len(segs) > 2 {
 		var err error
-		size, err = parseSizeString(segs[len(segs)-2])
+		size, err = parseSizeString(segs[len(segs)-2], m.Size)
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusBadRequest)
 			return 400, nil