[mutter/23-fix-icon-scaling: 4/4] theme: Fix icon scaling

[Florian Müllner <fmuellner src gnome org>]

commit 67bf936ef8a963cfe3d55913541fbce05dfa0878
Author: Egmont Koblinger <egmont gmail com>
Date:   Thu Mar 1 17:08:41 2018 +0100

    theme: Fix icon scaling
    
    When painting the titlebar, button icons that aren't available in the
    desired size need to be scaled. However the current code inverses the
    scale factor, with the result that the adjusted icons are much worse
    than the original icons, whoops.
    
    This went unnoticed for a long time given that most icons are availa-
    ble in the desired 16x16 size, and the most likely exceptions - window
    icons - are not shown by default.
    
    https://gitlab.gnome.org/GNOME/mutter/issues/23

 src/core/window.c | 4 ++--
 src/ui/theme.c    | 8 ++++----
 2 files changed, 6 insertions(+), 6 deletions(-)
---
diff --git a/src/core/window.c b/src/core/window.c
index 1a277ff12..f4ed4633b 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -446,12 +446,12 @@ meta_window_class_init (MetaWindowClass *klass)
   obj_props[PROP_ICON] =
     g_param_spec_pointer ("icon",
                           "Icon",
-                          "96 pixel sized icon",
+                          "Normal icon, usually 96x96 pixels",
                           G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
   obj_props[PROP_MINI_ICON] =
     g_param_spec_pointer ("mini-icon",
                           "Mini Icon",
-                          "16 pixel sized icon",
+                          "Mini icon, usually 16x16 pixels",
                           G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
   obj_props[PROP_DECORATED] =
     g_param_spec_boolean ("decorated",
diff --git a/src/ui/theme.c b/src/ui/theme.c
index 2f527fb24..2b3cd5eaf 100644
--- a/src/ui/theme.c
+++ b/src/ui/theme.c
@@ -885,13 +885,13 @@ meta_frame_layout_draw_with_style (MetaFrameLayout         *layout,
 
               width = cairo_image_surface_get_width (surface) / scale;
               height = cairo_image_surface_get_height (surface) / scale;
-              x = button_rect.x + (button_rect.width - width) / 2;
-              y = button_rect.y + (button_rect.height - height) / 2;
+              x = button_rect.x + (button_rect.width - layout->icon_size) / 2;
+              y = button_rect.y + (button_rect.height - layout->icon_size) / 2;
 
               cairo_translate (cr, x, y);
               cairo_scale (cr,
-                           width / layout->icon_size,
-                           height / layout->icon_size);
+                           layout->icon_size / width,
+                           layout->icon_size / height);
               cairo_set_source_surface (cr, surface, 0, 0);
               cairo_paint (cr);