[gtk+] scrolledwindow: Port to CSS nodes

[Matthias Clasen <matthiasc src gnome org>]

commit 80af6ff1307d151d27fc8a3f44098a58ed202ec5
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Nov 4 07:29:33 2015 -0500

    scrolledwindow: Port to CSS nodes
    
    Change GtkScrolledWindow to use transient named CSS nodes for
    drawing the overshoot, undershoot and scrollbar junction.

 gtk/gtkscrolledwindow.c |   41 +++++++++++++++++++++++------------------
 1 files changed, 23 insertions(+), 18 deletions(-)
---
diff --git a/gtk/gtkscrolledwindow.c b/gtk/gtkscrolledwindow.c
index e679c4f..7afdead 100644
--- a/gtk/gtkscrolledwindow.c
+++ b/gtk/gtkscrolledwindow.c
@@ -43,6 +43,7 @@
 #include "gtkwindow.h"
 #include "gtkkineticscrolling.h"
 #include "a11y/gtkscrolledwindowaccessible.h"
+#include "gtkstylecontextprivate.h"
 
 #include <math.h>
 
@@ -104,6 +105,16 @@
  * scrollbars are desired although no mouse is present, this behaviour
  * can be turned off with the #GtkScrolledWindow:overlay-scrolling
  * property.
+ *
+ * # CSS nodes
+ *
+ * GtkScrolledWindow has a main CSS node with name scrolledwindow.
+ * It uses transient subnodes with names overshoot and undershoot to
+ * draw the overflow and underflow indications. These nodes get
+ * the .left, .right, .top or .bottom style class added depending
+ * on where the indictaion is drawn. If both scrollbars are visible,
+ * the area where they meet is drawn with a transient subnode named
+ * junction.
  */
 
 
@@ -722,6 +733,7 @@ gtk_scrolled_window_class_init (GtkScrolledWindowClass *class)
   add_tab_bindings (binding_set, GDK_CONTROL_MASK | GDK_SHIFT_MASK, GTK_DIR_TAB_BACKWARD);
 
   gtk_widget_class_set_accessible_type (widget_class, GTK_TYPE_SCROLLED_WINDOW_ACCESSIBLE);
+  gtk_widget_class_set_css_name (widget_class, "scrolledwindow");
 }
 
 static gboolean
@@ -2142,8 +2154,7 @@ gtk_scrolled_window_draw_scrollbars_junction (GtkScrolledWindow *scrolled_window
       priv->window_placement == GTK_CORNER_TOP_RIGHT)
     junction_rect.y += vscr_allocation.height;
 
-  gtk_style_context_save (context);
-  gtk_style_context_add_class (context, GTK_STYLE_CLASS_SCROLLBARS_JUNCTION);
+  gtk_style_context_save_named (context, "junction");
 
   gtk_render_background (context, cr,
                          junction_rect.x, junction_rect.y,
@@ -2193,9 +2204,7 @@ gtk_scrolled_window_draw_overshoot (GtkScrolledWindow *scrolled_window,
   overshoot_x = CLAMP (overshoot_x, - MAX_OVERSHOOT_DISTANCE, MAX_OVERSHOOT_DISTANCE);
   overshoot_y = CLAMP (overshoot_y, - MAX_OVERSHOOT_DISTANCE, MAX_OVERSHOOT_DISTANCE);
 
-  gtk_style_context_save (context);
-  gtk_style_context_remove_class (context, GTK_STYLE_CLASS_FRAME);
-  gtk_style_context_add_class (context, GTK_STYLE_CLASS_OVERSHOOT);
+  gtk_style_context_save_named (context, "overshoot");
 
   if (overshoot_x > 0)
     {
@@ -2214,9 +2223,7 @@ gtk_scrolled_window_draw_overshoot (GtkScrolledWindow *scrolled_window,
 
   gtk_style_context_restore (context);
 
-  gtk_style_context_save (context);
-  gtk_style_context_remove_class (context, GTK_STYLE_CLASS_FRAME);
-  gtk_style_context_add_class (context, GTK_STYLE_CLASS_OVERSHOOT);
+  gtk_style_context_save_named (context, "overshoot");
 
   if (overshoot_y > 0)
     {
@@ -2249,51 +2256,49 @@ gtk_scrolled_window_draw_undershoot (GtkScrolledWindow *scrolled_window,
   context = gtk_widget_get_style_context (widget);
   gtk_scrolled_window_inner_allocation (widget, &rect);
 
-  gtk_style_context_save (context);
-  gtk_style_context_remove_class (context, GTK_STYLE_CLASS_FRAME);
-  gtk_style_context_add_class (context, GTK_STYLE_CLASS_UNDERSHOOT);
-
   adj = gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar));
   if (gtk_adjustment_get_value (adj) < gtk_adjustment_get_upper (adj) - gtk_adjustment_get_page_size (adj))
     {
+      gtk_style_context_save_named (context, "undershoot");
       gtk_style_context_add_class (context, GTK_STYLE_CLASS_RIGHT);
 
       gtk_render_background (context, cr, rect.x + rect.width - UNDERSHOOT_SIZE, rect.y, UNDERSHOOT_SIZE, 
rect.height);
       gtk_render_frame (context, cr, rect.x + rect.width - UNDERSHOOT_SIZE, rect.y, UNDERSHOOT_SIZE, 
rect.height);
 
-      gtk_style_context_remove_class (context, GTK_STYLE_CLASS_RIGHT);
+      gtk_style_context_restore (context);
     }
   if (gtk_adjustment_get_value (adj) > gtk_adjustment_get_lower (adj))
     {
+      gtk_style_context_save_named (context, "undershoot");
       gtk_style_context_add_class (context, GTK_STYLE_CLASS_LEFT);
 
       gtk_render_background (context, cr, rect.x, rect.y, UNDERSHOOT_SIZE, rect.height);
       gtk_render_frame (context, cr, rect.x, rect.y, UNDERSHOOT_SIZE, rect.height);
 
-      gtk_style_context_remove_class (context, GTK_STYLE_CLASS_LEFT);
+      gtk_style_context_restore (context);
     }
 
   adj = gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar));
   if (gtk_adjustment_get_value (adj) < gtk_adjustment_get_upper (adj) - gtk_adjustment_get_page_size (adj))
     {
+      gtk_style_context_save_named (context, "undershoot");
       gtk_style_context_add_class (context, GTK_STYLE_CLASS_BOTTOM);
 
       gtk_render_background (context, cr, rect.x, rect.y + rect.height - UNDERSHOOT_SIZE, rect.width, 
UNDERSHOOT_SIZE);
       gtk_render_frame (context, cr, rect.x, rect.y + rect.height - UNDERSHOOT_SIZE, rect.width, 
UNDERSHOOT_SIZE);
 
-      gtk_style_context_remove_class (context, GTK_STYLE_CLASS_BOTTOM);
+      gtk_style_context_restore (context);
     }
   if (gtk_adjustment_get_value (adj) > gtk_adjustment_get_lower (adj))
     {
+      gtk_style_context_save_named (context, "undershoot");
       gtk_style_context_add_class (context, GTK_STYLE_CLASS_TOP);
 
       gtk_render_background (context, cr, rect.x, rect.y, rect.width, UNDERSHOOT_SIZE);
       gtk_render_frame (context, cr, rect.x, rect.y, rect.width, UNDERSHOOT_SIZE);
 
-      gtk_style_context_remove_class (context, GTK_STYLE_CLASS_TOP);
+      gtk_style_context_restore (context);
     }
-
-  gtk_style_context_restore (context);
 }
 
 static gboolean