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 rect = gallery.getBoundingClientRect()
+                if(rect.width){
+                    livePreview.style.width = rect.width + "px"
+                    livePreview.style.height = rect.height + "px"
+                }
+
                 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 = ''
                     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%;