Return with and heigh of the generated images (#382)

* Return with and heigh of the generated images

Use case:

When using the fit image transformation, it is helpful to know the size
of the resulting image without having to either read the image locally
or do another request to the info endpoint.

Used in: https://github.com/nextcloud/server/pull/24166

Signed-off-by: Carl Schwan <carl@carlschwan.eu>

* Make mimetype support always return true

* Add command line option to enable this feature

Signed-off-by: Carl Schwan <carl@carlschwan.eu>

* refactor: remove deprecated X- prefix in response headers

Co-authored-by: Tom <tomas@aparicio.me>

controllers.go

@@ -133,6 +133,13 @@ func imageHandler(w http.ResponseWriter, r *http.Request, buf []byte, operation
 	// Expose Content-Length response header
 	w.Header().Set("Content-Length", strconv.Itoa(len(image.Body)))
 	w.Header().Set("Content-Type", image.Mime)
+	if image.Mime != "application/json" && o.ReturnSize {
+		meta, err := bimg.Metadata(image.Body)
+		if err == nil {
+			w.Header().Set("Image-Width", strconv.Itoa(meta.Size.Width))
+			w.Header().Set("Image-Height", strconv.Itoa(meta.Size.Height))
+		}
+	}
 	if vary != "" {
 		w.Header().Set("Vary", vary)
 	}

imaginary.go

@@ -50,6 +50,7 @@ var (
 	aMRelease           = flag.Int("mrelease", 30, "OS memory release interval in seconds")
 	aCpus               = flag.Int("cpus", runtime.GOMAXPROCS(-1), "Number of cpu cores to use")
 	aLogLevel           = flag.String("log-level", "info", "Define log level for http-server. E.g: info,warning,error")
+	aReturnSize         = flag.Bool("return-size", false, "Return the image size in the HTTP headers")
 )
 
 const usage = `imaginary %s
@@ -106,6 +107,7 @@ Options:
                              (default for current machine is %d cores)
   -log-level                 Set log level for http-server. E.g: info,warning,error [default: info].
                              Or can use the environment variable GOLANG_LOG=info.
+  -return-size               Return the image size with X-Width and X-Height HTTP header. [default: disabled].
 `
 
 type URLSignature struct {
@@ -157,6 +159,7 @@ func main() {
 		AllowedOrigins:     parseOrigins(*aAllowedOrigins),
 		MaxAllowedSize:     *aMaxAllowedSize,
 		LogLevel:           getLogLevel(*aLogLevel),
+		ReturnSize:         *aReturnSize,
 	}
 
 	// Show warning if gzip flag is passed

server.go

@@ -43,6 +43,7 @@ type ServerOptions struct {
 	Endpoints          Endpoints
 	AllowedOrigins     []*url.URL
 	LogLevel           string
+	ReturnSize         bool
 }
 
 // Endpoints represents a list of endpoint names to disable.