eliminate flicker for live previews

javascript/progressbar.js

@@ -184,15 +184,15 @@ function requestProgress(id_task, progressbarContainer, gallery, atEnd, onProgre
 
 
             if(res.live_preview){
-                var img = new Image();
-                img.onload = function() {
+
                 var rect = gallery.getBoundingClientRect()
                 if(rect.width){
                     livePreview.style.width = rect.width + "px"
                     livePreview.style.height = rect.height + "px"
                 }
 
-                    livePreview.innerHTML = ''
+                var img = new Image();
+                img.onload = function() {
                     livePreview.appendChild(img)
                     if(livePreview.childElementCount > 2){
                         livePreview.removeChild(livePreview.firstElementChild)

style.css

@@ -338,6 +338,7 @@ input[type="range"]{
 }
 
 .livePreview img{
+    position: absolute;
     object-fit: contain;
     width: 100%;
     height: 100%;