Fix thumbnail editing, add blobtodataurl method

projects/common/src/fm/services/image.service.ts

@@ -48,4 +48,18 @@ export class ImageService {
   blobToFile(blob:Blob, filename:string):File {
     return new File([blob],filename,{type:blob.type});
   }
+
+  blobToDataUrl(blob:File):Promise<string> {
+
+    return new Promise<string>((resolve) => {
+      let reader = new FileReader();
+      reader.addEventListener('error', () => {
+        resolve("");
+      });
+      reader.addEventListener("load", function () {
+        resolve(reader.result as string);
+      }, false);
+      reader.readAsDataURL(blob);
+    });
+  }
 }