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