Add scrolling with mouse to editor (#2028)

* Add scrolling with mouse to editor

* Fix compilation

Author: mrkubax10

src/editor/overlay_widget.cpp

@@ -60,8 +60,10 @@ EditorOverlayWidget::EditorOverlayWidget(Editor& editor) :
   m_hovered_corner(0, 0),
   m_sector_pos(0, 0),
   m_mouse_pos(0, 0),
+  m_previous_mouse_pos(0, 0),
   m_dragging(false),
   m_dragging_right(false),
+  m_scrolling(false),
   m_drag_start(0, 0),
   m_dragged_object(nullptr),
   m_hovered_object(nullptr),
@@ -859,6 +861,13 @@ EditorOverlayWidget::process_right_click()
   }
 }
 
+void
+EditorOverlayWidget::process_middle_click()
+{
+  m_previous_mouse_pos = m_mouse_pos;
+  m_scrolling = true;
+}
+
 Rectf
 EditorOverlayWidget::tile_drag_rect() const
 {
@@ -926,6 +935,8 @@ EditorOverlayWidget::on_mouse_button_up(const SDL_MouseButtonEvent& button)
       }
     }
   }
+  else if (button.button == SDL_BUTTON_MIDDLE)
+    m_scrolling = false;
 
   m_dragging = false;
 
@@ -947,6 +958,10 @@ EditorOverlayWidget::on_mouse_button_down(const SDL_MouseButtonEvent& button)
       process_right_click();
       return true;
 
+    case SDL_BUTTON_MIDDLE:
+      process_middle_click();
+      return true;
+
     default:
       return false;
   }
@@ -994,6 +1009,12 @@ EditorOverlayWidget::on_mouse_motion(const SDL_MouseMotionEvent& motion)
     }
     return true;
   }
+  else if (m_scrolling)
+  {
+    m_editor.scroll(m_previous_mouse_pos - m_mouse_pos);
+    m_previous_mouse_pos = m_mouse_pos;
+    return true;
+  }
   else
   {
     return false;

src/editor/overlay_widget.hpp

@@ -102,6 +102,7 @@ class EditorOverlayWidget final : public Widget
 
   void process_left_click();
   void process_right_click();
+  void process_middle_click();
 
   // sp is sector pos, tp is pos on tilemap.
   Vector tp_to_sp(const Vector& tp, int tile_size = 32) const;
@@ -121,9 +122,11 @@ class EditorOverlayWidget final : public Widget
   Vector m_hovered_corner;
   Vector m_sector_pos;
   Vector m_mouse_pos;
+  Vector m_previous_mouse_pos;
 
   bool m_dragging;
   bool m_dragging_right;
+  bool m_scrolling;
   Vector m_drag_start;
   TypedUID<MovingObject> m_dragged_object;