[eog/wip/baedert/gtkimageview] scroll-view: Use a gesture for dragging

[Timm Bäder <baedert src gnome org>]

commit 7465284be25cd253917d8e4f283eaea9595d6040
Author: Timm Bäder <mail baedert org>
Date:   Sat Mar 19 20:02:25 2016 +0100

    scroll-view: Use a gesture for dragging

 src/eog-scroll-view.c |  220 +++++++++++++++++--------------------------------
 1 files changed, 77 insertions(+), 143 deletions(-)
---
diff --git a/src/eog-scroll-view.c b/src/eog-scroll-view.c
index 2c86bf8..4fced9b 100644
--- a/src/eog-scroll-view.c
+++ b/src/eog-scroll-view.c
@@ -131,9 +131,8 @@ struct _EogScrollViewPrivate {
        gdouble zoom_multiplier;
 
        /* dragging stuff */
-       int drag_anchor_x, drag_anchor_y;
-       int drag_ofs_x, drag_ofs_y;
-       guint dragging : 1;
+       double drag_anchor_x;
+       double drag_anchor_y;
 
        /* how to indicate transparency in images */
        EogTransparencyStyle transp_style;
@@ -149,6 +148,8 @@ struct _EogScrollViewPrivate {
        cairo_surface_t *background_surface;
 
        GtkGesture *pan_gesture;
+       GtkGesture *drag_gesture;
+
        gdouble initial_zoom;
        EogRotationState rotate_state;
        EogPanAction pan_action;
@@ -439,24 +440,6 @@ scroll_by (EogScrollView *view, int xofs, int yofs)
        scroll_to (view, _xofs + xofs, _yofs + yofs);
 }
 
-/* Drags the image to the specified position */
-static void
-drag_to (EogScrollView *view, int x, int y)
-{
-       EogScrollViewPrivate *priv;
-       int dx, dy;
-
-       priv = view->priv;
-
-       dx = priv->drag_anchor_x - x;
-       dy = priv->drag_anchor_y - y;
-
-       x = priv->drag_ofs_x + dx;
-       y = priv->drag_ofs_y + dy;
-
-       scroll_to (view, x, y);
-}
-
 static void
 set_minimum_zoom_factor (EogScrollView *view)
 {
@@ -675,105 +658,6 @@ display_key_press_event (GtkWidget *widget, GdkEventKey *event, gpointer data)
        return TRUE;
 }
 
-
-/* Button press event handler for the image view */
-static gboolean
-eog_scroll_view_button_press_event (GtkWidget *widget, GdkEventButton *event, gpointer data)
-{
-       EogScrollView *view;
-       EogScrollViewPrivate *priv;
-
-       view = EOG_SCROLL_VIEW (data);
-       priv = view->priv;
-
-       if (!gtk_widget_has_focus (priv->display))
-               gtk_widget_grab_focus (GTK_WIDGET (priv->display));
-
-       if (priv->dragging)
-               return GDK_EVENT_PROPAGATE;
-
-       switch (event->button) {
-               case 1:
-               case 2:
-                       if (event->button == 1 && !priv->scroll_wheel_zoom &&
-                           !(event->state & GDK_CONTROL_MASK))
-                               break;
-
-                       if (is_image_movable (view)) {
-                           eog_scroll_view_set_cursor (view, EOG_SCROLL_VIEW_CURSOR_DRAG);
-
-                               priv->dragging = TRUE;
-                               priv->drag_anchor_x = event->x;
-                               priv->drag_anchor_y = event->y;
-
-                               priv->drag_ofs_x = (int) gtk_adjustment_get_value (priv->hadj);
-                               priv->drag_ofs_y = (int) gtk_adjustment_get_value (priv->vadj);
-
-                               return GDK_EVENT_STOP;
-                       }
-               default:
-                       break;
-       }
-
-       return GDK_EVENT_PROPAGATE;
-}
-
-/* Button release event handler for the image view */
-static gboolean
-eog_scroll_view_button_release_event (GtkWidget *widget, GdkEventButton *event, gpointer data)
-{
-       EogScrollView *view;
-       EogScrollViewPrivate *priv;
-
-       view = EOG_SCROLL_VIEW (data);
-       priv = view->priv;
-
-       if (!priv->dragging)
-               return FALSE;
-
-       switch (event->button) {
-               case 1:
-               case 2:
-                       drag_to (view, event->x, event->y);
-                       priv->dragging = FALSE;
-
-                       eog_scroll_view_set_cursor (view, EOG_SCROLL_VIEW_CURSOR_NORMAL);
-                       break;
-
-               default:
-                       break;
-       }
-
-       return TRUE;
-}
-
-/* Motion event handler for the image view */
-static gboolean
-eog_scroll_view_motion_event (GtkWidget *widget, GdkEventMotion *event, gpointer data)
-{
-       EogScrollView *view;
-       EogScrollViewPrivate *priv;
-       gint x, y;
-       GdkModifierType mods;
-
-       view = EOG_SCROLL_VIEW (data);
-       priv = view->priv;
-
-       if (!priv->dragging)
-               return GDK_EVENT_PROPAGATE;
-
-       if (event->is_hint) {
-               gdk_window_get_device_position (gtk_widget_get_window (GTK_WIDGET (priv->display)),
-                                               event->device, &x, &y, &mods);
-       } else {
-               x = event->x;
-               y = event->y;
-       }
-
-       drag_to (view, x, y);
-       return GDK_EVENT_STOP;
-}
-
 static void
 display_size_change (GtkWidget *widget, GdkEventConfigure *event, gpointer data)
 {
@@ -928,9 +812,9 @@ display_draw (GtkWidget *widget, cairo_t *cr, gpointer data)
 
 static void
 pan_gesture_pan_cb (GtkGesturePan   *gesture,
-                   GtkPanDirection  direction,
-                   gdouble          offset,
-                   EogScrollView   *view)
+                    GtkPanDirection  direction,
+                    gdouble          offset,
+                    EogScrollView   *view)
 {
        EogScrollViewPrivate *priv;
 
@@ -958,8 +842,8 @@ pan_gesture_pan_cb (GtkGesturePan   *gesture,
 
 static void
 pan_gesture_end_cb (GtkGesture       *gesture,
-                   GdkEventSequence *sequence,
-                   EogScrollView    *view)
+                    GdkEventSequence *sequence,
+                    EogScrollView    *view)
 {
        EogScrollViewPrivate *priv;
 
@@ -976,6 +860,56 @@ pan_gesture_end_cb (GtkGesture       *gesture,
        priv->pan_action = EOG_PAN_ACTION_NONE;
 }
 
+static void
+drag_begin_cb (GtkGesture *gesture,
+               double      start_x,
+               double      start_y,
+               gpointer    user_data)
+{
+       EogScrollView *view = user_data;
+       EogScrollViewPrivate *priv = view->priv;
+
+       if (!is_image_movable (view)) {
+               g_message ("not movable");
+               gtk_gesture_set_state (gesture, GTK_EVENT_SEQUENCE_DENIED);
+               return;
+       }
+
+       gtk_gesture_set_state (gesture, GTK_EVENT_SEQUENCE_CLAIMED);
+
+       g_message (__FUNCTION__);
+       priv->drag_anchor_x = gtk_adjustment_get_value (priv->hadj);
+       priv->drag_anchor_y = gtk_adjustment_get_value (priv->vadj);
+
+       eog_scroll_view_set_cursor (view, EOG_SCROLL_VIEW_CURSOR_DRAG);
+}
+
+static void
+drag_update_cb (GtkGesture *gesture,
+                double      offset_x,
+                double      offset_y,
+                gpointer    user_data)
+{
+       EogScrollViewPrivate *priv = EOG_SCROLL_VIEW (user_data)->priv;
+       double new_value_x;
+       double new_value_y;
+
+       new_value_x = priv->drag_anchor_x - offset_x;
+       new_value_y = priv->drag_anchor_y - offset_y;
+
+       gtk_adjustment_set_value (priv->hadj, new_value_x);
+       gtk_adjustment_set_value (priv->vadj, new_value_y);
+}
+
+static void
+drag_end_cb (GtkGesture *gesture,
+             double      offset_x,
+             double      offset_y,
+             gpointer    user_data)
+{
+       eog_scroll_view_set_cursor (user_data, EOG_SCROLL_VIEW_CURSOR_NORMAL);
+}
+
 /*===================================
          public API
   ---------------------------------*/
@@ -1470,19 +1404,9 @@ eog_scroll_view_init (EogScrollView *view)
        g_signal_connect (G_OBJECT (priv->display), "configure_event",
                          G_CALLBACK (display_size_change), view);
 
-
        g_signal_connect (G_OBJECT (priv->display), "draw",
                          G_CALLBACK (display_draw), view);
 
-
-       g_signal_connect (G_OBJECT (priv->display), "button_press_event",
-                         G_CALLBACK (eog_scroll_view_button_press_event),
-                         view);
-       g_signal_connect (G_OBJECT (priv->display), "motion_notify_event",
-                         G_CALLBACK (eog_scroll_view_motion_event), view);
-       g_signal_connect (G_OBJECT (priv->display), "button_release_event",
-                         G_CALLBACK (eog_scroll_view_button_release_event),
-                         view);
        g_signal_connect (G_OBJECT (priv->display), "focus_in_event",
                          G_CALLBACK (eog_scroll_view_focus_in_event), NULL);
        g_signal_connect (G_OBJECT (priv->display), "focus_out_event",
@@ -1524,16 +1448,25 @@ eog_scroll_view_init (EogScrollView *view)
 
        g_object_unref (settings);
 
-       priv->pan_gesture = gtk_gesture_pan_new (GTK_WIDGET (view),
-                                                GTK_ORIENTATION_HORIZONTAL);
+
+
+
+       priv->pan_gesture = gtk_gesture_pan_new (GTK_WIDGET (view), GTK_ORIENTATION_HORIZONTAL);
        g_signal_connect (priv->pan_gesture, "pan",
-                         G_CALLBACK (pan_gesture_pan_cb), view);
+                         G_CALLBACK (pan_gesture_pan_cb), view);
        g_signal_connect (priv->pan_gesture, "end",
-                         G_CALLBACK (pan_gesture_end_cb), view);
-       gtk_gesture_single_set_touch_only (GTK_GESTURE_SINGLE (priv->pan_gesture),
-                                          TRUE);
+                         G_CALLBACK (pan_gesture_end_cb), view);
+       gtk_gesture_single_set_touch_only (GTK_GESTURE_SINGLE (priv->pan_gesture), TRUE);
        gtk_event_controller_set_propagation_phase (GTK_EVENT_CONTROLLER (priv->pan_gesture),
-                                                   GTK_PHASE_CAPTURE);
+                                                   GTK_PHASE_CAPTURE);
+
+       priv->drag_gesture = gtk_gesture_drag_new (GTK_WIDGET (view));
+       g_signal_connect (priv->drag_gesture, "drag-begin",
+                         G_CALLBACK (drag_begin_cb), view);
+       g_signal_connect (priv->drag_gesture, "drag-update",
+                         G_CALLBACK (drag_update_cb), view);
+       g_signal_connect (priv->drag_gesture, "drag-end",
+                         G_CALLBACK (drag_end_cb), view);
 
        /* left revealer */
        priv->left_revealer = gtk_revealer_new ();
@@ -1667,7 +1600,8 @@ eog_scroll_view_dispose (GObject *object)
 
        free_image_resources (view);
 
-       g_clear_object(&priv->pan_gesture);
+       g_clear_object (&priv->pan_gesture);
+       g_clear_object (&priv->drag_gesture);
 
        G_OBJECT_CLASS (eog_scroll_view_parent_class)->dispose (object);
 }