[gnome-games] game-thumbnail: Support HiDPI

[Alexander Mikhaylenko <alexm src gnome org>]

commit 2c694894772cc35cbb2fe1241c9a082bf9fdceeb
Author: Alexander Mikhaylenko <exalm7659 gmail com>
Date:   Sat Aug 17 15:20:48 2019 +0500

    game-thumbnail: Support HiDPI
    
    Load larger covers, and draw them downscaled, ensuring they are as crisp
    as possible.

 src/ui/game-thumbnail.vala | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)
---
diff --git a/src/ui/game-thumbnail.vala b/src/ui/game-thumbnail.vala
index 05f8776f..b7238735 100644
--- a/src/ui/game-thumbnail.vala
+++ b/src/ui/game-thumbnail.vala
@@ -196,14 +196,14 @@ private class Games.GameThumbnail : Gtk.DrawingArea {
        }
 
        private Gdk.Pixbuf? get_scaled_cover (DrawingContext context) {
-               if (previous_cover_width != context.width) {
-                       previous_cover_width = context.width;
+               if (previous_cover_width != context.width * scale_factor) {
+                       previous_cover_width = context.width * scale_factor;
                        cover_cache = null;
                        tried_loading_cover = false;
                }
 
-               if (previous_cover_height != context.height) {
-                       previous_cover_height = context.height;
+               if (previous_cover_height != context.height * scale_factor) {
+                       previous_cover_height = context.height * scale_factor;
                        cover_cache = null;
                        tried_loading_cover = false;
                }
@@ -211,7 +211,7 @@ private class Games.GameThumbnail : Gtk.DrawingArea {
                if (cover_cache != null)
                        return cover_cache;
 
-               var size = int.min (context.width, context.height);
+               var size = int.min (context.width, context.height) * scale_factor;
 
                load_cover_cache_from_disk (context, size);
                if (cover_cache != null)
@@ -253,8 +253,10 @@ private class Games.GameThumbnail : Gtk.DrawingArea {
                }
 
                try {
-                       cover_cache = new Gdk.Pixbuf.from_file_at_scale (cover_cache_path, context.width,
-                                                                        context.height, true);
+                       cover_cache = new Gdk.Pixbuf.from_file_at_scale (cover_cache_path,
+                                                                        context.width * scale_factor,
+                                                                        context.height * scale_factor,
+                                                                        true);
                }
                catch (Error e) {
                        debug (e.message);
@@ -300,22 +302,28 @@ private class Games.GameThumbnail : Gtk.DrawingArea {
        private void draw_pixbuf (DrawingContext context, Gdk.Pixbuf pixbuf) {
                var surface = Gdk.cairo_surface_create_from_pixbuf (pixbuf, 1, context.window);
 
+               context.cr.save ();
+               context.cr.scale (1.0 / scale_factor, 1.0 / scale_factor);
+
                var mask = get_mask (context);
 
-               var x_offset = (context.width - pixbuf.width) / 2;
-               var y_offset = (context.height - pixbuf.height) / 2;
+               var x_offset = (context.width * scale_factor - pixbuf.width) / 2;
+               var y_offset = (context.height * scale_factor - pixbuf.height) / 2;
 
                context.cr.set_source_surface (surface, x_offset, y_offset);
                context.cr.mask_surface (mask, 0, 0);
+
+               context.cr.restore ();
        }
 
        private Cairo.Surface get_mask (DrawingContext context) {
-               var mask = new Cairo.ImageSurface (Cairo.Format.A8, context.width, context.height);
+               var mask = new Cairo.ImageSurface (Cairo.Format.A8, context.width * scale_factor, 
context.height * scale_factor);
 
                var border_radius = (int) context.style.get_property (Gtk.STYLE_PROPERTY_BORDER_RADIUS, 
context.state);
                border_radius = border_radius.clamp (0, int.max (context.width / 2, context.height / 2));
 
                var cr = new Cairo.Context (mask);
+               cr.scale (scale_factor, scale_factor);
                cr.set_source_rgb (0, 0, 0);
                rounded_rectangle (cr, 0.5, 0.5, context.width - 1, context.height - 1, border_radius);
                cr.fill ();