Define drawing function of CellularPanel, which visits nodes

src/TrackPanelDrawable.h

@@ -0,0 +1,51 @@
+/**********************************************************************
+
+Audacity: A Digital Audio Editor
+
+TrackPanelDrawable.h
+
+Paul Licameli
+
+**********************************************************************/
+
+#ifndef __AUDACITY_TRACK_PANEL_DRAWABLE__
+#define __AUDACITY_TRACK_PANEL_DRAWABLE__
+
+struct TrackPanelDrawingContext;
+struct wxRect;
+
+/// \brief Drawing interface common to cells, groups of cells, and temporary handles in CellularPanel
+class TrackPanelDrawable {
+public:
+   virtual ~TrackPanelDrawable() = 0;
+
+   // Drawing functions of the subdivision are visited repeatedly in one
+   // painting if their areas (as computed by DrawingArea) intersect the
+   // panel area, and depending on iPass may overpaint results of previous
+   // passes.
+   // Drawing function is given the rectangle computed by DrawingArea.
+   // iPass counts zero-based up to some limit given to CellularPanel::Draw.
+   // Default implementation does nothing.
+   virtual void Draw(
+      TrackPanelDrawingContext &context, const wxRect &rect, unsigned iPass );
+
+   // For drawing purposes, a cell might require a bigger rectangle than for
+   // hit-test purposes, spilling over into other parts of the partition of the
+   // panel area.
+   // Default implementation returns rect unchanged.
+   virtual wxRect DrawingArea(
+      const wxRect &rect, const wxRect &panelRect, unsigned iPass );
+
+   // Utilities for implementing DrawingArea:
+   static inline wxRect MaximizeWidth(
+      const wxRect &rect, const wxRect &panelRect ) {
+      return { panelRect.x, rect.y, panelRect.width, rect.height };
+   }
+
+   static inline wxRect MaximizeHeight(
+      const wxRect &rect, const wxRect &panelRect ) {
+      return { rect.x, panelRect.y, rect.width, panelRect.height };
+   }
+};
+
+#endif