Add SVG studio image support, and studio image caching (#418)

* Support SVGs for studio images and add ETAGs
* Add SVG to studio image input
* Update content sniffing

pkg/api/routes_studio.go

@@ -2,10 +2,13 @@ package api
 
 import (
 	"context"
+	"crypto/md5"
+	"fmt"
 	"github.com/go-chi/chi"
 	"github.com/stashapp/stash/pkg/models"
 	"net/http"
 	"strconv"
+	"strings"
 )
 
 type studioRoutes struct{}
@@ -23,6 +26,21 @@ func (rs studioRoutes) Routes() chi.Router {
 
 func (rs studioRoutes) Image(w http.ResponseWriter, r *http.Request) {
 	studio := r.Context().Value(studioKey).(*models.Studio)
+	etag := fmt.Sprintf("%x", md5.Sum(studio.Image))
+	if match := r.Header.Get("If-None-Match"); match != "" {
+		if strings.Contains(match, etag) {
+			w.WriteHeader(http.StatusNotModified)
+			return
+		}
+	}
+
+	contentType := http.DetectContentType(studio.Image)
+	if contentType == "text/xml; charset=utf-8" || contentType == "text/plain; charset=utf-8" {
+		contentType = "image/svg+xml"
+	}
+
+	w.Header().Set("Content-Type", contentType)
+	w.Header().Add("Etag", etag)
 	_, _ = w.Write(studio.Image)
 }