From 1c780beb8b194d18ff86ca53f30b0c6c522bfc0d Mon Sep 17 00:00:00 2001
From: Matthias Clasen <mclasen@redhat.com>
Date: Sun, 12 Jul 2015 01:36:17 -0400
Subject: [PATCH] range: Add a stepper alternative

Make shift right-click on the trough start autoscrolling. The
autoscrolling is similar to the way steppers operate now, with
the difference that we vary the scrolling speed based on the
distance of the pointer from the widget.
---
 gtk/gtkrange.c | 60 +++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 50 insertions(+), 10 deletions(-)

diff --git a/gtk/gtkrange.c b/gtk/gtkrange.c
index d65364a648..9a41f20e04 100644
--- a/gtk/gtkrange.c
+++ b/gtk/gtkrange.c
@@ -752,6 +752,7 @@ gtk_range_init (GtkRange *range)
    * widget.
    */
   priv->drag_gesture = gtk_gesture_drag_new (GTK_WIDGET (range));
+  gtk_gesture_single_set_button (GTK_GESTURE_SINGLE (priv->drag_gesture), 0);
   g_signal_connect (priv->drag_gesture, "drag-begin",
                     G_CALLBACK (gtk_range_drag_gesture_begin), range);
   g_signal_connect (priv->drag_gesture, "drag-update",
@@ -2479,6 +2480,7 @@ gtk_range_multipress_gesture_pressed (GtkGestureMultiPress *gesture,
   gboolean primary_warps;
   gint page_increment_button, warp_button;
   guint button;
+  GdkModifierType state_mask;
 
   if (!gtk_widget_has_focus (widget))
     gtk_widget_grab_focus (widget);
@@ -2486,6 +2488,7 @@ gtk_range_multipress_gesture_pressed (GtkGestureMultiPress *gesture,
   sequence = gtk_gesture_single_get_current_sequence (GTK_GESTURE_SINGLE (gesture));
   button = gtk_gesture_single_get_current_button (GTK_GESTURE_SINGLE (gesture));
   event = gtk_gesture_get_last_event (GTK_GESTURE (gesture), sequence);
+  gdk_event_get_state (event, &state_mask);
 
   source_device = gdk_event_get_source_device ((GdkEvent *) event);
   source = gdk_device_get_source (source_device);
@@ -2537,7 +2540,16 @@ gtk_range_multipress_gesture_pressed (GtkGestureMultiPress *gesture,
 
       scroll = range_get_scroll_for_grab (range);
 
-      gtk_range_add_step_timer (range, scroll);
+      if (state_mask & GDK_SHIFT_MASK)
+        {
+          remove_autoscroll (range);
+          range->priv->autoscroll_mode = priv->trough_click_forward ? GTK_SCROLL_END : GTK_SCROLL_START;
+          add_autoscroll (range);
+        }
+      else
+        {
+          gtk_range_add_step_timer (range, scroll);
+        }
     }
   else if ((priv->mouse_location == MOUSE_STEPPER_A ||
             priv->mouse_location == MOUSE_STEPPER_B ||
@@ -2601,10 +2613,6 @@ gtk_range_multipress_gesture_pressed (GtkGestureMultiPress *gesture,
         }
       else
         {
-          GdkModifierType state_mask;
-
-          gdk_event_get_state (event, &state_mask);
-
           /* Shift-click in the slider = fine adjustment */
           if (state_mask & GDK_SHIFT_MASK)
             update_zoom_state (range, TRUE);
@@ -2748,20 +2756,53 @@ autoscroll_cb (GtkWidget     *widget,
   gdouble increment;
   gdouble value;
   gboolean handled;
+  gdouble step, page;
+
+  step = gtk_adjustment_get_step_increment (adj);
+  page = gtk_adjustment_get_page_increment (adj);
 
   switch (priv->autoscroll_mode)
     {
     case GTK_SCROLL_STEP_FORWARD:
-      increment = gtk_adjustment_get_step_increment (adj) / AUTOSCROLL_FACTOR;
+      increment = step / AUTOSCROLL_FACTOR;
       break;
     case GTK_SCROLL_PAGE_FORWARD:
-      increment = gtk_adjustment_get_page_increment (adj) / AUTOSCROLL_FACTOR;
+      increment = page / AUTOSCROLL_FACTOR;
       break;
     case GTK_SCROLL_STEP_BACKWARD:
-      increment = - gtk_adjustment_get_step_increment (adj) / AUTOSCROLL_FACTOR;
+      increment = - step / AUTOSCROLL_FACTOR;
       break;
     case GTK_SCROLL_PAGE_BACKWARD:
-      increment = - gtk_adjustment_get_page_increment (adj) / AUTOSCROLL_FACTOR;
+      increment = - page / AUTOSCROLL_FACTOR;
+      break;
+    case GTK_SCROLL_START:
+    case GTK_SCROLL_END:
+      {
+        gdouble x, y;
+        gdouble distance, t;
+
+        /* Vary scrolling speed from slow (ie step) to fast (2 * page),
+         * based on the distance of the pointer from the widget. We start
+         * speeding up if the pointer moves at least 20 pixels away, and
+         * we reach maximum speed when it is 220 pixels away.
+         */
+        if (!gtk_gesture_drag_get_offset (GTK_GESTURE_DRAG (priv->drag_gesture), &x, &y))
+          {
+            x = 0.0;
+            y = 0.0;
+          }
+        if (gtk_orientable_get_orientation (GTK_ORIENTABLE (range)) == GTK_ORIENTATION_HORIZONTAL)
+          distance = fabs (y);
+        else
+          distance = fabs (x);
+        distance = CLAMP (distance - 20, 0.0, 200);
+        t = distance / 100.0;
+        step = (1 - t) * step + t * page;
+        if (priv->autoscroll_mode == GTK_SCROLL_END)
+          increment = step / AUTOSCROLL_FACTOR;
+        else
+          increment = - step / AUTOSCROLL_FACTOR;
+      }
       break;
     default:
       g_assert_not_reached ();
@@ -2944,7 +2985,6 @@ gtk_range_drag_gesture_begin (GtkGestureDrag *gesture,
 {
   if (range->priv->grab_location == MOUSE_SLIDER)
     gtk_gesture_set_state (range->priv->drag_gesture, GTK_EVENT_SEQUENCE_CLAIMED);
-
 }
 
 static void
-- 
2.30.2