[gtk: 3/8] broadway: Ensure images are decoded, not only loaded

[Matthias Clasen <matthiasc src gnome org>]

commit 43598fc5f2ed2bc1b1655b593172b8378cb1cfce
Author: Alexander Larsson <alexl redhat com>
Date:   Fri Mar 13 08:56:56 2020 +0100

    broadway: Ensure images are decoded, not only loaded
    
    In firefox, onload will trigger when the image is loaded, but at
    that point it may not be decoded yet so showing it will sometimers
    trigger flashes. We use the new decode() feature instead which ensures
    both that the image is loaded *and* decoded, thus fixing the flashes.

 gdk/broadway/broadway.js | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)
---
diff --git a/gdk/broadway/broadway.js b/gdk/broadway/broadway.js
index 2478aacc7c..5b8311427c 100644
--- a/gdk/broadway/broadway.js
+++ b/gdk/broadway/broadway.js
@@ -274,6 +274,7 @@ function Texture(id, data) {
     var image = new Image();
     image.src = this.url;
     this.image = image;
+    this.decoded = image.decode();
     textures[id] = this;
 }
 
@@ -1237,16 +1238,14 @@ function handleOutstanding()
         outstandingDisplayCommands = display_commands;
 
     if (new_textures.length > 0) {
-        var n_textures = new_textures.length;
+        var decodes = [];
         for (var i = 0; i < new_textures.length; i++) {
-            var t = new_textures[i];
-            t.image.onload = function() {
-                n_textures -= 1;
-                if (n_textures == 0) {
-                    handleOutstandingDisplayCommands();
-                }
-            };
+            decodes.push(new_textures[i].decoded);
         }
+        Promise.allSettled(decodes).then(
+            () => {
+                handleOutstandingDisplayCommands();
+            });
     } else {
         handleOutstandingDisplayCommands();
     }