GLUI: support click & drag in instrument editor sample to scroll & zoom

Fixes #22.

Signed-off-by: Stefan Westerfeld <[email protected]>

glui/sminsteditwindow.cc

@@ -207,13 +207,14 @@ InstEditWindow::InstEditWindow (EventLoop& event_loop, Instrument *edit_instrume
   grid.add_widget (sample_scroll_view, 1, 8, 91, 46);
 
   sample_widget = new SampleWidget (sample_scroll_view);
+  connect (sample_widget->signal_drag_scroll, this, &InstEditWindow::on_drag_scroll);
 
   grid.add_widget (sample_widget, 1, 1, 100, 42);
   sample_scroll_view->set_scroll_widget (sample_widget, true, false, /* center_zoom */ true);
 
   /*----- hzoom -----*/
   grid.add_widget (new Label (this, "HZoom"), 1, 54, 6, 3);
-  Slider *hzoom_slider = new Slider (this, 0.0);
+  hzoom_slider = new Slider (this, 0.0);
   grid.add_widget (hzoom_slider, 7, 54, 28, 3);
   connect (hzoom_slider->signal_value_changed, this, &InstEditWindow::on_update_hzoom);
 
@@ -623,6 +624,15 @@ InstEditWindow::on_remove_sample_clicked()
   instrument->remove_sample();
 }
 
+void
+InstEditWindow::on_drag_scroll (double cx, double dx, double dy)
+{
+  hzoom_slider->set_value (std::clamp<double> (hzoom_slider->value() - dy * 0.003, 0, 1));
+  double factor = pow (2, hzoom_slider->value() * 10);
+  sample_scroll_view->change_widget_x_and_width (cx, dx, 89 * factor * 8);
+  hzoom_label->set_text (string_printf ("%.1f %%", factor * 100));
+}
+
 void
 InstEditWindow::on_update_hzoom (float value)
 {

glui/sminsteditwindow.hh

@@ -27,6 +27,7 @@ class CheckBox;
 class Button;
 class Timer;
 class ComboBox;
+class Slider;
 class SampleWidget;
 class SynthInterface;
 
@@ -73,10 +74,11 @@ class InstEditWindow : public Window
   Sample::Loop  text_to_loop (const std::string& text);
   std::string   loop_to_text (const Sample::Loop loop);
 
-  ComboBox *sample_combobox;
-  ScrollView *sample_scroll_view;
-  Label *hzoom_label;
-  Label *vzoom_label;
+  ComboBox    *sample_combobox;
+  ScrollView  *sample_scroll_view;
+  Label       *hzoom_label = nullptr;
+  Label       *vzoom_label = nullptr;
+  Slider      *hzoom_slider = nullptr;
   PlayMode play_mode = PlayMode::SPECTMORPH;
   ComboBox *play_mode_combobox;
   ComboBox *loop_combobox;
@@ -114,6 +116,7 @@ public:
   void on_remove_sample_clicked();
   void on_update_hzoom (float value);
   void on_update_vzoom (float value);
+  void on_drag_scroll (double cx, double dx, double dy);
   void on_show_hide_params();
   void on_show_hide_note();
   void on_import_clicked();

glui/smsamplewidget.hh

@@ -56,6 +56,9 @@ private:
   Sample       *m_sample = nullptr;
   MarkerType    selected_marker = MARKER_NONE;
   bool          mouse_down = false;
+  double        mouse_click_x = 0;
+  double        mouse_click_y = 0;
+  double        mouse_click_pos = 0;
   DisplayTuning m_display_tuning;
 
   std::map<MarkerType, Rect> marker_rect;
@@ -298,7 +301,15 @@ public:
     if (mouse_down)
       {
         if (selected_marker == MARKER_NONE)
-          return;
+          {
+            double dx = event.x + abs_x() - mouse_click_x;
+            double dy = event.y - mouse_click_y;
+            mouse_click_x = event.x + abs_x();
+            mouse_click_y = event.y;
+
+            signal_drag_scroll (mouse_click_pos, dx, dy);
+            return;
+          }
 
         const double sample_len_ms = m_sample->wav_data().samples().size() / m_sample->wav_data().mix_freq() * 1000.0;
         const double x_ms = sm_bound<double> (0, event.x / width() * sample_len_ms, sample_len_ms);
@@ -332,7 +343,12 @@ public:
   mouse_press (const MouseEvent& event) override
   {
     if (event.button == LEFT_BUTTON)
-      mouse_down = true;
+      {
+        mouse_down = true;
+        mouse_click_x = event.x + abs_x();
+        mouse_click_y = event.y;
+        mouse_click_pos = event.x / width();
+      }
   }
   void
   mouse_release (const MouseEvent& event) override
@@ -413,6 +429,7 @@ public:
   {
     update();
   }
+  Signal<double, double, double> signal_drag_scroll;
 };
 
 }

glui/smscrollview.hh

@@ -144,6 +144,19 @@ public:
     // reposition widget on screen if necessary
     on_scroll_bar_changed (0);
   }
+  void
+  change_widget_x_and_width (double cx, double dx, double width)
+  {
+    double old_width = scroll_widget->width();
+    scroll_widget->set_width (width);
+    double x = scroll_widget->x() + dx - (width - old_width) * cx;
+    double new_page_size = view_width / (scroll_widget->width() + 16);
+    h_scroll_bar->set_page_size (new_page_size);
+    double new_pos = (8 - x) / (scroll_widget->width() + 16);
+    new_pos = std::clamp (new_pos, 0.0, 1 - new_page_size);
+    h_scroll_bar->set_pos (new_pos);
+    on_scroll_bar_changed (0);
+  }
 };
 
 }