[gnome-games/async-cover: 3/3] game-thumbnail: Use size-allocate to load thumbnails

[Abhinav Singh <abhinavsingh src gnome org>]

commit d05a6501cae39484550366eca2a44db0f27d6f49
Author: theawless <theawless gmail com>
Date:   Sat Oct 6 23:01:56 2018 +0530

    game-thumbnail: Use size-allocate to load thumbnails
    
    This reduces the number of calls being to load the thumbnails, thereby
    improving performance.

 src/ui/game-thumbnail.vala | 70 ++++++++++++++++++++++++----------------------
 1 file changed, 36 insertions(+), 34 deletions(-)
---
diff --git a/src/ui/game-thumbnail.vala b/src/ui/game-thumbnail.vala
index 77ae4b3e..f34e8ed8 100644
--- a/src/ui/game-thumbnail.vala
+++ b/src/ui/game-thumbnail.vala
@@ -13,8 +13,7 @@ private class Games.GameThumbnail: Gtk.DrawingArea {
 
                        _uid = value;
 
-                       icon_cache = null;
-                       invalidate_cover ();
+                       load_cache.begin (cache_width, cache_height);
                }
        }
 
@@ -27,8 +26,7 @@ private class Games.GameThumbnail: Gtk.DrawingArea {
 
                        _icon = value;
 
-                       icon_cache = null;
-                       queue_draw ();
+                       load_cache.begin (cache_width, cache_height);
                }
        }
 
@@ -41,15 +39,15 @@ private class Games.GameThumbnail: Gtk.DrawingArea {
 
                        _cover = value;
 
-                       invalidate_cover ();
+                       load_cache.begin (cache_width, cache_height);
                }
        }
 
-       private bool tried_loading_cover;
        private Gdk.Pixbuf? icon_cache;
        private Gdk.Pixbuf? cover_cache;
        private int cache_width;
        private int cache_height;
+       private GenericSet<Gtk.Allocation?> allocations;
 
        public struct DrawingContext {
                Cairo.Context cr;
@@ -64,6 +62,12 @@ private class Games.GameThumbnail: Gtk.DrawingArea {
                set_css_name ("gamesgamethumbnail");
        }
 
+       construct {
+               // Use a custom equal function because we do not need to check the other members of the 
allocation.
+               allocations = new GenericSet<Gtk.Allocation?> ((a) => a.width,
+                                                              (a, b) => a.width == b.width && a.height == 
b.height);
+       }
+
        public override Gtk.SizeRequestMode get_request_mode () {
                return Gtk.SizeRequestMode.HEIGHT_FOR_WIDTH;
        }
@@ -83,16 +87,6 @@ private class Games.GameThumbnail: Gtk.DrawingArea {
                        cr, window, style, state, width, height
                };
 
-               if (cache_height != context.height || cache_width != context.width) {
-                       cache_height = context.height;
-                       cache_width = context.width;
-                       icon_cache = null;
-                       cover_cache = null;
-                       tried_loading_cover = false;
-               }
-
-               load_cache.begin (context.width, context.height);
-
                draw_border (context);
                if (cover_cache != null)
                        draw_black_background (context);
@@ -106,14 +100,33 @@ private class Games.GameThumbnail: Gtk.DrawingArea {
                return true;
        }
 
-       private async void load_cache (int width, int height) {
-               if (cover_cache == null && icon_cache == null) {
-                       var cache = yield get_cover_cache (width, height);
-                       if (width == cache_width && height == cache_height)
-                               cover_cache = cache;
+       public override void size_allocate (Gtk.Allocation allocation) {
+               base.size_allocate (allocation);
+
+               if (cache_height != allocation.height || cache_width != allocation.width) {
+                       cache_height = allocation.height;
+                       cache_width = allocation.width;
+                       icon_cache = null;
+                       cover_cache = null;
+
+                       if (!allocations.contains (allocation)) {
+                               allocations.add (allocation);
+                               load_cache.begin (cache_width, cache_height, () => {
+                                       allocations.remove (allocation);
+                               });
+                       }
                }
-               if (cover_cache == null && icon_cache == null) {
-                       var cache = yield get_icon_cache (width, height);
+       }
+
+       private async void load_cache (int width, int height) {
+               if (width == 0 || height == 0)
+                       return;
+
+               var cache = yield get_cover_cache (width, height);
+               if (width == cache_width && height == cache_height)
+                       cover_cache = cache;
+               if (cover_cache == null) {
+                       cache = yield get_icon_cache (width, height);
                        if (width == cache_width && height == cache_height)
                                icon_cache = cache;
                }
@@ -199,11 +212,6 @@ private class Games.GameThumbnail: Gtk.DrawingArea {
        }
 
        private Gdk.Pixbuf? load_cover_cache_from_disk (int width, int height) {
-               if (tried_loading_cover)
-                       return null;
-
-               tried_loading_cover = true;
-
                var size = int.min (width, height);
                string cover_cache_path;
                try {
@@ -249,12 +257,6 @@ private class Games.GameThumbnail: Gtk.DrawingArea {
                return @"$dir/$uid.png";
        }
 
-       private void invalidate_cover () {
-               cover_cache = null;
-               tried_loading_cover = false;
-               queue_draw ();
-       }
-
        private void draw_pixbuf (DrawingContext context, Gdk.Pixbuf pixbuf) {
                var surface = Gdk.cairo_surface_create_from_pixbuf (pixbuf, 1, context.window);