#pragma once

#include "HashableRect.h"

class ImageGroup;

// This class implements a cached bitmap of a given OZO_XXX zorder layer.

class OverlayCachedLayer
{
  public:
    OverlayCachedLayer(void);
    virtual ~OverlayCachedLayer(void);

    // Draws this cached layer onto the given dc.
    void draw(HDC dcHandle);

    // Locks for drawing.
    HDC lock(void);

    // Unlocks from drawing.
    void unlock(void)

    // Updates the dimension of the overlay canvas.
    void setDimensions(const CSize& dimensions);

  private:
    // The bitmap used to provide flicker-free update of the canvas.
    ImageGroup* m_offscreen;

    // Map of rects that need to be redrawn.
    // This is a hash table to make sure all rects are unique --- this has
    // the nice side-effect that if an overlay makes its rect dirty a
    // successive number of times and does not move, only one dirty
    // rect will be stored.
    // The bool values mean nothing.
    CMap<HashableRect, const HashableRect&, bool, bool> m_dirtyRectMap;
};

void
OverlayCachedLayer::unlock(const CSize& dimensions)
{
  
}