Kinetic scrolling implemented as requested in bug #461271. Thanks to David

2007-12-25  Nickolay V. Shmyrev  <nshmyrev@yandex.ru>

	* shell/ev-view-private.h:
	* shell/ev-view.c: (ev_view_drag_update_momentum),
	(ev_view_scroll_drag_release), (ev_view_motion_notify_event),
	(ev_view_button_release_event), (ev_view_destroy):

	Kinetic scrolling implemented as requested in
	bug #461271. Thanks to David Turner <cillian64@googlemail.com>.

svn path=/trunk/; revision=2783

diff --git a/ChangeLog b/ChangeLog
index 6561210618a4e3430037bccbd359d18db68d6427..cb0830ab655eda9beee17880a30dc1fb3abc3ae4 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2007-12-25  Nickolay V. Shmyrev  <nshmyrev@yandex.ru>
+
+       * shell/ev-view-private.h:
+       * shell/ev-view.c: (ev_view_drag_update_momentum),
+       (ev_view_scroll_drag_release), (ev_view_motion_notify_event),
+       (ev_view_button_release_event), (ev_view_destroy):
+       
+       Kinetic scrolling implemented as requested in
+       bug #461271. Thanks to David Turner <cillian64@googlemail.com>.
+
 2007-12-23  Nickolay V. Shmyrev  <nshmyrev@yandex.ru>
 
        * data/evince-toolbar.xml:

diff --git a/shell/ev-view-private.h b/shell/ev-view-private.h
index 22bd7a0e76b7863c15822c5e806e3d44d52331c8..a2a2812541554d65c1f687ac2c47ee13213230f4 100644 (file)
--- a/shell/ev-view-private.h
+++ b/shell/ev-view-private.h
@@ -28,12 +28,18 @@
 #include "ev-form-field.h"
 #include "ev-selection.h"
 
+#define DRAG_HISTORY 10
+
 /* Information for middle clicking and moving around the doc */
 typedef struct {
         gboolean in_drag;
        GdkPoint start;
        gdouble hadj;
        gdouble vadj;
+       guint drag_timeout_id;
+       guint release_timeout_id;
+       GdkPoint buffer[DRAG_HISTORY];
+       GdkPoint momentum;
 } DragInfo;
 
 /* Autoscrolling */

diff --git a/shell/ev-view.c b/shell/ev-view.c
index c4baa7c19a5131ff492a16c4f8813032eb1e5410..9782d0b1a472c3682dc01e01b34d3a4ee29555b3 100644 (file)
--- a/shell/ev-view.c
+++ b/shell/ev-view.c
@@ -2892,6 +2892,66 @@ selection_scroll_timeout_cb (EvView *view)
        return TRUE;
 }
 
+static gboolean
+ev_view_drag_update_momentum (EvView *view)
+{
+       int i;
+       if (!view->drag_info.in_drag)
+               return FALSE;
+       
+       for (i = DRAG_HISTORY - 1; i > 0; i--) {
+               view->drag_info.buffer[i].x = view->drag_info.buffer[i-1].x;
+               view->drag_info.buffer[i].y = view->drag_info.buffer[i-1].y;
+       }
+
+       /* Momentum is a moving average of 10ms granularity over
+        * the last 100ms with each 10ms stored in buffer. 
+        */
+       
+       view->drag_info.momentum.x = (view->drag_info.buffer[DRAG_HISTORY - 1].x - view->drag_info.buffer[0].x);
+       view->drag_info.momentum.y = (view->drag_info.buffer[DRAG_HISTORY - 1].y - view->drag_info.buffer[0].y);
+
+       return TRUE;
+}
+
+static gboolean
+ev_view_scroll_drag_release (EvView *view)
+{
+       gdouble dhadj_value, dvadj_value;
+       gdouble oldhadjustment, oldvadjustment;
+
+       view->drag_info.momentum.x /= 1.2;
+       view->drag_info.momentum.y /= 1.2; /* Alter these constants to change "friction" */
+
+       dhadj_value = view->hadjustment->page_size *
+                     (gdouble)view->drag_info.momentum.x / GTK_WIDGET (view)->allocation.width;
+       dvadj_value = view->vadjustment->page_size *
+                     (gdouble)view->drag_info.momentum.y / GTK_WIDGET (view)->allocation.height;
+
+       oldhadjustment = gtk_adjustment_get_value (view->hadjustment);
+       oldvadjustment = gtk_adjustment_get_value (view->vadjustment);
+
+       if (((oldhadjustment + dhadj_value) > (view->hadjustment->upper - view->hadjustment->page_size)) ||
+          ((oldhadjustment + dhadj_value) < 0))
+               view->drag_info.momentum.x *= -0.5; /* 0.5 rather than 1 means the edges absorb some momentum */
+       if (((oldvadjustment + dvadj_value) > (view->vadjustment->upper - view->vadjustment->page_size)) ||
+          ((oldvadjustment + dvadj_value) < 0))
+               view->drag_info.momentum.y *= -0.5;
+
+       gtk_adjustment_set_value (view->hadjustment,
+                               MIN (oldhadjustment + dhadj_value,
+                               view->hadjustment->upper - view->hadjustment->page_size));
+       gtk_adjustment_set_value (view->vadjustment,
+                               MIN (oldvadjustment + dvadj_value,
+                               view->vadjustment->upper - view->vadjustment->page_size));
+
+       if (((view->drag_info.momentum.x < 1) && (view->drag_info.momentum.x > -1)) &&
+          ((view->drag_info.momentum.y < 1) && (view->drag_info.momentum.y > -1)))
+               return FALSE;
+       else
+               return TRUE;
+}
+
 static gboolean
 ev_view_motion_notify_event (GtkWidget      *widget,
                             GdkEventMotion *event)
@@ -2983,6 +3043,7 @@ ev_view_motion_notify_event (GtkWidget      *widget,
        } else if (view->pressed_button == 2) {
                if (!view->drag_info.in_drag) {
                        gboolean start;
+                       int i;
 
                        start = gtk_drag_check_threshold (widget,
                                                          view->drag_info.start.x,
@@ -2990,12 +3051,25 @@ ev_view_motion_notify_event (GtkWidget      *widget,
                                                          event->x_root,
                                                          event->y_root);
                        view->drag_info.in_drag = start;
+                       view->drag_info.drag_timeout_id = g_timeout_add (10,
+                               (GSourceFunc)ev_view_drag_update_momentum, view);
+                       /* Set 100 to choose how long it takes to build up momentum */
+                       /* Clear out previous momentum info: */
+                       for (i = 0; i < DRAG_HISTORY; i++) {
+                               view->drag_info.buffer[i].x = event->x;
+                               view->drag_info.buffer[i].y = event->y;
+                       }
+                       view->drag_info.momentum.x = 0;
+                       view->drag_info.momentum.y = 0;
                }
 
                if (view->drag_info.in_drag) {
                        int dx, dy;
                        gdouble dhadj_value, dvadj_value;
 
+                       view->drag_info.buffer[0].x = event->x;
+                       view->drag_info.buffer[0].y = event->y;
+
                        dx = event->x_root - view->drag_info.start.x;
                        dy = event->y_root - view->drag_info.start.y;
 
@@ -3033,6 +3107,9 @@ ev_view_button_release_event (GtkWidget      *widget,
 
        view->drag_info.in_drag = FALSE;
        view->image_dnd_info.in_drag = FALSE;
+       
+       view->drag_info.release_timeout_id = g_timeout_add (20,
+                       (GSourceFunc)ev_view_scroll_drag_release, view);
 
        if (view->pressed_button == 2) {
                ev_view_handle_cursor_over_xy (view, event->x, event->y);
@@ -3048,10 +3125,6 @@ ev_view_button_release_event (GtkWidget      *widget,
            g_source_remove (view->selection_scroll_id);
            view->selection_scroll_id = 0;
        }
-       if (view->scroll_info.timeout_id) {
-           g_source_remove (view->scroll_info.timeout_id);
-           view->scroll_info.timeout_id = 0;
-       }
        if (view->selection_update_id) {
            g_source_remove (view->selection_update_id);
            view->selection_update_id = 0;
@@ -3764,6 +3837,21 @@ ev_view_destroy (GtkObject *object)
                view->loading_text = NULL;
        }
 
+       if (view->scroll_info.timeout_id) {
+           g_source_remove (view->scroll_info.timeout_id);
+           view->scroll_info.timeout_id = 0;
+       }
+
+       if (view->drag_info.drag_timeout_id) {
+               g_source_remove (view->drag_info.drag_timeout_id);
+               view->drag_info.drag_timeout_id = 0;
+       }
+
+       if (view->drag_info.release_timeout_id) {
+               g_source_remove (view->drag_info.release_timeout_id);
+               view->drag_info.release_timeout_id = 0;
+       }
+
        ev_view_presentation_transition_stop (view);
 
        ev_view_set_scroll_adjustments (GTK_LAYOUT (view), NULL, NULL);