range: read and use CSS margin values for the trough component

Many themes want to render the trough background/stroke thinner than the
full height/width (which is constructed around the value of the
'slider-width' style property).
Read and apply the CSS margin from the theme on the trough component, so
that themes can make it smaller at their will without the need to
override the render_background, render_frame and render_activity methods
of GtkThemingEngine.

https://bugzilla.gnome.org/show_bug.cgi?id=676196

diff --git a/gtk/gtkrange.c b/gtk/gtkrange.c
index 981d700e8df6493997d3b4fb7d93b03b33d14889..529a8d76a96a4ce5f698e26b27731ee1fb3e18ea 100644 (file)
--- a/gtk/gtkrange.c
+++ b/gtk/gtkrange.c
@@ -2010,6 +2010,7 @@ gtk_range_draw (GtkWidget *widget,
   gboolean draw_trough = TRUE;
   gboolean draw_slider = TRUE;
   GtkStyleContext *context;
+  GtkBorder margin;
 
   context = gtk_widget_get_style_context (widget);
 
@@ -2107,6 +2108,12 @@ gtk_range_draw (GtkWidget *widget,
 
       gtk_style_context_save (context);
       gtk_style_context_add_class (context, GTK_STYLE_CLASS_TROUGH);
+      gtk_style_context_get_margin (context, widget_state, &margin);
+
+      x += margin.left;
+      y += margin.top;
+      width -= margin.left + margin.right;
+      height -= margin.top + margin.bottom;
 
       if (draw_trough)
         {
@@ -3576,13 +3583,15 @@ gtk_range_calc_layout (GtkRange *range,
   GtkRangePrivate *priv = range->priv;
   gint slider_width, stepper_size, focus_width, trough_border, stepper_spacing;
   gint slider_length;
-  GtkBorder border;
+  GtkBorder border, trough_margin;
   gint n_steppers;
   gboolean has_steppers_ab;
   gboolean has_steppers_cd;
   gboolean trough_under_steppers;
   GdkRectangle range_rect;
   GtkWidget *widget;
+  GtkStyleContext *context;
+  GtkStateFlags state;
 
   if (!priv->need_recalc)
     return;
@@ -3598,6 +3607,13 @@ gtk_range_calc_layout (GtkRange *range,
    */
 
   widget = GTK_WIDGET (range);
+  context = gtk_widget_get_style_context (widget);
+
+  state = gtk_widget_get_state_flags (widget);
+  gtk_style_context_save (context);
+  gtk_style_context_add_class (context, GTK_STYLE_CLASS_TROUGH);
+  gtk_style_context_get_margin (context, state, &trough_margin);
+  gtk_style_context_restore (context);
 
   gtk_range_get_props (range,
                        &slider_width, &stepper_size,
@@ -3716,16 +3732,16 @@ gtk_range_calc_layout (GtkRange *range,
       /* Now the trough is the remaining space between steppers B and C,
        * if any, minus spacing
        */
-      priv->trough.x = range_rect.x;
-      priv->trough.y = priv->stepper_b.y + priv->stepper_b.height + stepper_spacing * has_steppers_ab;
-      priv->trough.width = range_rect.width;
-      priv->trough.height = priv->stepper_c.y - priv->trough.y - stepper_spacing * has_steppers_cd;
+      priv->trough.x = range_rect.x + trough_margin.left;
+      priv->trough.y = priv->stepper_b.y + priv->stepper_b.height + stepper_spacing * has_steppers_ab + trough_margin.top;
+      priv->trough.width = range_rect.width - trough_margin.left - trough_margin.right;
+      priv->trough.height = priv->stepper_c.y - priv->trough.y - stepper_spacing * has_steppers_cd - trough_margin.bottom;
 
       /* Slider fits into the trough, with stepper_spacing on either side,
        * and the size/position based on the adjustment or fixed, depending.
        */
-      priv->slider.x = priv->trough.x + focus_width + trough_border;
-      priv->slider.width = priv->trough.width - (focus_width + trough_border) * 2;
+      priv->slider.x = range_rect.x + focus_width + trough_border;
+      priv->slider.width = range_rect.width - (focus_width + trough_border) * 2;
 
       /* Compute slider position/length */
       {
@@ -3864,17 +3880,16 @@ gtk_range_calc_layout (GtkRange *range,
       /* Now the trough is the remaining space between steppers B and C,
        * if any
        */
-      priv->trough.x = priv->stepper_b.x + priv->stepper_b.width + stepper_spacing * has_steppers_ab;
-      priv->trough.y = range_rect.y;
-
-      priv->trough.width = priv->stepper_c.x - priv->trough.x - stepper_spacing * has_steppers_cd;
-      priv->trough.height = range_rect.height;
+      priv->trough.x = priv->stepper_b.x + priv->stepper_b.width + stepper_spacing * has_steppers_ab + trough_margin.left;
+      priv->trough.y = range_rect.y + trough_margin.top;
+      priv->trough.width = priv->stepper_c.x - priv->trough.x - stepper_spacing * has_steppers_cd - trough_margin.right;
+      priv->trough.height = range_rect.height - trough_margin.top - trough_margin.bottom;
 
       /* Slider fits into the trough, with stepper_spacing on either side,
        * and the size/position based on the adjustment or fixed, depending.
        */
-      priv->slider.y = priv->trough.y + focus_width + trough_border;
-      priv->slider.height = priv->trough.height - (focus_width + trough_border) * 2;
+      priv->slider.y = range_rect.y + focus_width + trough_border;
+      priv->slider.height = range_rect.height - (focus_width + trough_border) * 2;
 
       /* Compute slider position/length */
       {