[gtk+] GtkSpinButton: don't constantly recreate style contexts for buttons

[Owen Taylor <otaylor src gnome org>]

commit 0032b2dc5ad4c5faffb58565a3e4589335005c9e
Author: Owen W. Taylor <otaylor fishsoup net>
Date:   Tue Apr 23 13:12:07 2013 -0400

    GtkSpinButton: don't constantly recreate style contexts for buttons
    
    Cache the style contexts for the up and down panels, instead of recreating
    them each time they are drawn or size requested. GtkSpinButtons were
    many times slower to draw than other widgets because of the constant
    style matching.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=698682

 gtk/gtkspinbutton.c |   58 ++++++++++++++++++++++++++++++++++++++++++--------
 1 files changed, 48 insertions(+), 10 deletions(-)
---
diff --git a/gtk/gtkspinbutton.c b/gtk/gtkspinbutton.c
index 0928d9e..0f97078 100644
--- a/gtk/gtkspinbutton.c
+++ b/gtk/gtkspinbutton.c
@@ -156,6 +156,9 @@ struct _GtkSpinButtonPrivate
   GdkWindow     *down_panel;
   GdkWindow     *up_panel;
 
+  GtkStyleContext *down_panel_context;
+  GtkStyleContext *up_panel_context;
+
   GdkWindow     *click_child;
   GdkWindow     *in_child;
 
@@ -248,6 +251,7 @@ static void gtk_spin_button_grab_notify    (GtkWidget          *widget,
                                             gboolean            was_grabbed);
 static void gtk_spin_button_state_flags_changed  (GtkWidget     *widget,
                                                   GtkStateFlags  previous_state);
+static void gtk_spin_button_style_updated   (GtkWidget         *widget);
 static gboolean gtk_spin_button_timer          (GtkSpinButton      *spin_button);
 static gboolean gtk_spin_button_stop_spinning  (GtkSpinButton      *spin);
 static void gtk_spin_button_value_changed  (GtkAdjustment      *adjustment,
@@ -328,6 +332,7 @@ gtk_spin_button_class_init (GtkSpinButtonClass *class)
   widget_class->focus_out_event = gtk_spin_button_focus_out;
   widget_class->grab_notify = gtk_spin_button_grab_notify;
   widget_class->state_flags_changed = gtk_spin_button_state_flags_changed;
+  widget_class->style_updated = gtk_spin_button_style_updated;
 
   entry_class->activate = gtk_spin_button_activate;
   entry_class->get_text_area_size = gtk_spin_button_get_text_area_size;
@@ -684,7 +689,16 @@ gtk_spin_button_init (GtkSpinButton *spin_button)
 static void
 gtk_spin_button_finalize (GObject *object)
 {
-  gtk_spin_button_set_adjustment (GTK_SPIN_BUTTON (object), NULL);
+  GtkSpinButton *spin_button = GTK_SPIN_BUTTON (object);
+  GtkSpinButtonPrivate *priv = spin_button->priv;
+
+  gtk_spin_button_set_adjustment (spin_button, NULL);
+
+  if (priv->down_panel_context)
+    g_object_unref (priv->down_panel_context);
+
+  if (priv->up_panel_context)
+    g_object_unref (priv->up_panel_context);
 
   G_OBJECT_CLASS (gtk_spin_button_parent_class)->finalize (object);
 }
@@ -730,7 +744,7 @@ gtk_spin_button_unmap (GtkWidget *widget)
 static void
 gtk_spin_button_panel_nthchildize_context (GtkSpinButton *spin_button,
                                            GtkStyleContext *context,
-                                           GdkWindow *panel)
+                                           gboolean         is_down_panel)
 {
   GtkSpinButtonPrivate *priv = spin_button->priv;
   GtkWidget *widget = GTK_WIDGET (spin_button);
@@ -777,7 +791,7 @@ gtk_spin_button_panel_nthchildize_context (GtkSpinButton *spin_button,
   gtk_widget_path_iter_add_class (siblings_path, up_pos, GTK_STYLE_CLASS_SPINBUTTON);
   gtk_widget_path_iter_add_class (siblings_path, down_pos, GTK_STYLE_CLASS_SPINBUTTON);
 
-  if (panel == priv->down_panel)
+  if (is_down_panel)
     gtk_widget_path_append_with_siblings (path, siblings_path, down_pos);
   else
     gtk_widget_path_append_with_siblings (path, siblings_path, up_pos);
@@ -846,12 +860,20 @@ static GtkStyleContext *
 gtk_spin_button_panel_get_context (GtkSpinButton *spin_button,
                                    GdkWindow *panel)
 {
-  GtkStyleContext *context;
+  GtkSpinButtonPrivate *priv = spin_button->priv;
+  GtkStyleContext **contextp;
 
-  context = gtk_style_context_new ();
-  gtk_spin_button_panel_nthchildize_context (spin_button, context, panel);
+  contextp = (panel == priv->down_panel) ?
+    &priv->down_panel_context : &priv->up_panel_context;
+
+  if (*contextp == NULL)
+    {
+      *contextp = gtk_style_context_new ();
+      gtk_spin_button_panel_nthchildize_context (spin_button, *contextp,
+                                                 panel == priv->down_panel);
+    }
 
-  return context;
+  return *contextp;
 }
 
 static void
@@ -874,8 +896,6 @@ gtk_spin_button_panel_get_size (GtkSpinButton *spin_button,
   gtk_style_context_get_padding (context, state, &button_padding);
   gtk_style_context_get_border (context, state, &button_border);
 
-  g_object_unref (context);
-
   if (width)
     *width = icon_size + button_padding.left + button_padding.right +
              button_border.left + button_border.right;
@@ -1004,7 +1024,6 @@ gtk_spin_button_panel_draw (GtkSpinButton   *spin_button,
   cairo_restore (cr);
 
   g_object_unref (icon_helper);
-  g_object_unref (context);
 }
 
 static void
@@ -1361,6 +1380,25 @@ gtk_spin_button_state_flags_changed (GtkWidget     *widget,
     }
 }
 
+static void
+gtk_spin_button_style_updated (GtkWidget *widget)
+{
+  GtkSpinButton *spin = GTK_SPIN_BUTTON (widget);
+  GtkSpinButtonPrivate *priv = spin->priv;
+
+  if (priv->down_panel_context)
+    gtk_spin_button_panel_nthchildize_context (spin,
+                                               priv->down_panel_context,
+                                               TRUE);
+
+  if (priv->up_panel_context)
+    gtk_spin_button_panel_nthchildize_context (spin,
+                                               priv->up_panel_context,
+                                               FALSE);
+
+  GTK_WIDGET_CLASS (gtk_spin_button_parent_class)->style_updated (widget);
+}
+
 static gint
 gtk_spin_button_scroll (GtkWidget      *widget,
                         GdkEventScroll *event)