+
+enum {
+ GIS_DRAG_NONE,
+ GIS_DRAG_PAN,
+ GIS_DRAG_ZOOM,
+ GIS_DRAG_TILT,
+};
+
+static gboolean on_button_press(GisViewer *viewer, GdkEventButton *event, gpointer _)
+{
+ g_debug("GisViewer: on_button_press - %d", event->button);
+ gtk_widget_grab_focus(GTK_WIDGET(viewer));
+ switch (event->button) {
+ case 1: viewer->drag_mode = GIS_DRAG_PAN; break;
+ case 2: viewer->drag_mode = GIS_DRAG_ZOOM; break;
+ case 3: viewer->drag_mode = GIS_DRAG_TILT; break;
+ defualt: viewer->drag_mode = GIS_DRAG_NONE; break;
+ }
+ viewer->drag_x = event->x;
+ viewer->drag_y = event->y;
+ return FALSE;
+}
+
+static gboolean on_button_release(GisViewer *viewer, GdkEventButton *event, gpointer _)
+{
+ g_debug("GisViewer: on_button_release");
+ viewer->drag_mode = GIS_DRAG_NONE;
+ return FALSE;
+}
+
+static gboolean on_motion_notify(GisViewer *viewer, GdkEventMotion *event, gpointer _)
+{
+ gdouble x_dist = viewer->drag_x - event->x;
+ gdouble y_dist = viewer->drag_y - event->y;
+ gdouble lat, lon, elev, scale;
+ gis_viewer_get_location(GIS_VIEWER(viewer), &lat, &lon, &elev);
+ scale = elev/EARTH_R/15;
+ switch (viewer->drag_mode) {
+ case GIS_DRAG_PAN:
+ gis_viewer_pan(viewer, -y_dist*scale, x_dist*scale, 0);
+ break;
+ case GIS_DRAG_ZOOM:
+ gis_viewer_zoom(viewer, pow(2, -y_dist/500));
+ break;
+ case GIS_DRAG_TILT:
+ gis_viewer_rotate(viewer, y_dist/10, 0, x_dist/10);
+ break;
+ }
+ viewer->drag_x = event->x;
+ viewer->drag_y = event->y;
+ return FALSE;
+}
+
+static void on_view_changed(GisViewer *viewer,