gtk-stats: Support trackpad zoom/pan gestures in Timeline view

pandatool/src/gtk-stats/gtkStatsTimeline.cxx

@@ -54,7 +54,8 @@ GtkStatsTimeline(GtkStatsMonitor *monitor) :
                    G_CALLBACK(thread_area_draw_callback), this);
 
   // Listen for mouse wheel and keyboard events.
-  gtk_widget_add_events(_graph_window, GDK_SCROLL_MASK |
+  gtk_widget_add_events(_graph_window, GDK_SMOOTH_SCROLL_MASK |
+                                       GDK_SCROLL_MASK |
                                        GDK_KEY_PRESS_MASK |
                                        GDK_KEY_RELEASE_MASK);
   gtk_widget_set_can_focus(_graph_window, TRUE);
@@ -65,6 +66,25 @@ GtkStatsTimeline(GtkStatsMonitor *monitor) :
   g_signal_connect(G_OBJECT(_graph_window), "key_release_event",
                    G_CALLBACK(key_release_callback), this);
 
+  // Set up trackpad pinch and swipe gestures.
+  _zoom_gesture = gtk_gesture_zoom_new(_graph_window);
+  g_signal_connect(_zoom_gesture, "begin",
+    G_CALLBACK(+[](GtkGestureZoom *gesture, GdkEventSequence *sequence, gpointer data) {
+      GtkStatsTimeline *self = (GtkStatsTimeline *)data;
+      self->_zoom_scale = self->get_horizontal_scale();
+    }), this);
+
+  g_signal_connect(_zoom_gesture, "scale-changed",
+    G_CALLBACK((+[](GtkGestureZoom *gesture, gdouble scale, gpointer data) {
+      GtkStatsTimeline *self = (GtkStatsTimeline *)data;
+      gdouble x, y;
+      if (gtk_gesture_get_point(GTK_GESTURE(gesture), NULL, &x, &y)) {
+        int graph_x = (int)(x * self->_cr_scale);
+        self->zoom_by(log(scale) * 0.8, self->pixel_to_timestamp(graph_x));
+        self->start_animation();
+      }
+    })), this);
+
   int min_height = 0;
   if (!_threads.empty()) {
     double height = row_to_pixel(get_num_rows()) + _pixel_scale * 2.5;
@@ -100,6 +120,7 @@ GtkStatsTimeline(GtkStatsMonitor *monitor) :
 GtkStatsTimeline::
 ~GtkStatsTimeline() {
   cairo_pattern_destroy(_grid_pattern);
+  g_object_unref(_zoom_gesture);
 }
 
 /**
@@ -627,6 +648,16 @@ handle_scroll(int graph_x, int graph_y, double dx, double dy, bool ctrl_held) {
   return handled;
 }
 
+/**
+ *
+ */
+gboolean GtkStatsTimeline::
+handle_zoom(int graph_x, int graph_y, double scale) {
+  zoom_to(get_horizontal_scale() / scale, pixel_to_timestamp(graph_x));
+  start_animation();
+  return TRUE;
+}
+
 /**
  *
  */

pandatool/src/gtk-stats/gtkStatsTimeline.h

@@ -63,6 +63,7 @@ protected:
   virtual gboolean handle_leave();
   gboolean handle_scroll(int graph_x, int graph_y,
                          double dx, double dy, bool ctrl_held);
+  gboolean handle_zoom(int graph_x, int graph_y, double scale);
   gboolean handle_key(bool pressed, guint val, guint16 hw_code);
 
 private:
@@ -92,6 +93,9 @@ private:
   int _highlighted_x = 0;
   int _scroll = 0;
   ColorBar _popup_bar;
+
+  double _zoom_scale = 1.0;
+  GtkGesture *_zoom_gesture = nullptr;
 };
 
 #endif