[gtk+] range: Have slider jump to the pointer coordinates on touch devices

[Matthias Clasen <matthiasc src gnome org>]

commit 518a5798383b54c19ab535462b0251863c1a4079
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu Jan 5 00:21:36 2012 +0100

    range: Have slider jump to the pointer coordinates on touch devices
    
    This widget is too narrow to make touch interaction tricky enough, so
    don't add the penalty of having the slider run farther from the touch
    coordinates if it happens to miss the slider.

 gtk/gtkrange.c |   23 ++++++++++++++---------
 1 files changed, 14 insertions(+), 9 deletions(-)
---
diff --git a/gtk/gtkrange.c b/gtk/gtkrange.c
index 23a4991..b920d00 100644
--- a/gtk/gtkrange.c
+++ b/gtk/gtkrange.c
@@ -2522,7 +2522,8 @@ gtk_range_button_press (GtkWidget      *widget,
 {
   GtkRange *range = GTK_RANGE (widget);
   GtkRangePrivate *priv = range->priv;
-  GdkDevice *device;
+  GdkDevice *device, *source_device;
+  GdkInputSource source;
 
   if (!gtk_widget_has_focus (widget))
     gtk_widget_grab_focus (widget);
@@ -2532,6 +2533,9 @@ gtk_range_button_press (GtkWidget      *widget,
     return FALSE;
 
   device = gdk_event_get_device ((GdkEvent *) event);
+  source_device = gdk_event_get_source_device ((GdkEvent *) event);
+  source = gdk_device_get_source (source_device);
+
   priv->mouse_x = event->x;
   priv->mouse_y = event->y;
 
@@ -2548,23 +2552,24 @@ gtk_range_button_press (GtkWidget      *widget,
       return TRUE;
     }
 
-  if (priv->mouse_location == MOUSE_TROUGH  &&
+  if (source != GDK_SOURCE_TOUCHSCREEN &&
+      priv->mouse_location == MOUSE_TROUGH &&
       event->button == GDK_BUTTON_PRIMARY)
     {
       /* button 1 steps by page increment, as with button 2 on a stepper
        */
       GtkScrollType scroll;
       gdouble click_value;
-      
+
       click_value = coord_to_value (range,
                                     priv->orientation == GTK_ORIENTATION_VERTICAL ?
                                     event->y : event->x);
 
       priv->trough_click_forward = click_value > gtk_adjustment_get_value (priv->adjustment);
       range_grab_add (range, device, MOUSE_TROUGH, event->button);
-      
+
       scroll = range_get_scroll_for_grab (range);
-      
+
       gtk_range_add_step_timer (range, scroll);
 
       return TRUE;
@@ -2599,17 +2604,17 @@ gtk_range_button_press (GtkWidget      *widget,
       return TRUE;
     }
   else if ((priv->mouse_location == MOUSE_TROUGH &&
-            event->button == GDK_BUTTON_MIDDLE) ||
+            (source == GDK_SOURCE_TOUCHSCREEN || event->button == GDK_BUTTON_MIDDLE)) ||
            priv->mouse_location == MOUSE_SLIDER)
     {
       gboolean need_value_update = FALSE;
 
       /* Any button can be used to drag the slider, but you can start
        * dragging the slider with a trough click using button 2;
-       * On button 2 press, we warp the slider to mouse position,
-       * then begin the slider drag.
+       * On button 2 press and touch devices, we warp the slider to
+       * mouse position, then begin the slider drag.
        */
-      if (event->button == GDK_BUTTON_MIDDLE)
+      if (event->button == GDK_BUTTON_MIDDLE || source == GDK_SOURCE_TOUCHSCREEN)
         {
           gdouble slider_low_value, slider_high_value, new_value;