2D Water Effect in WTL

// WaterEffectImplBase.h : the WaterEffectImplBase & WaterEffectCtl classes
// Written by Tan, Zhi(tomgee) 4/28/2011
/////////////////////////////////////////////////////////////////////////////

#pragma once

#include "WaterEffect.h"
#include "Renderer.h"

#include <atlcrack.h>
#include <atlimage.h>
#include <atltrace.h>


// for usage as a base class
template<class Derived>
class WaterEffectImplBase : public CMessageMap
{
private:
	CRenderer m_renderer;
	CWaterEffect m_waterEffect;
	CRect m_rectDraw;
private:
	enum
	{
		DRAW	 = 1,
		BLOB	 = 2
	};
public:
	BEGIN_MSG_MAP_EX(WaterEffectImplBase)
		MSG_WM_TIMER(OnTimer)
		MSG_WM_MOUSEMOVE(OnMouseMove)
	END_MSG_MAP()

public:
	void init(_U_STRINGorID  nIDResource, const CPoint& topleft = CPoint(0,0))
	{		
		CImage m_image;
		m_image.LoadFromResource(_Module.m_hInst, nIDResource.m_lpstr);

		init(m_image, topleft);
	}

	void init(const CImage& image, const CPoint& topleft = CPoint(0,0))
	{		
		CClientDC dc(static_cast<Derived*>(this)->m_hWnd);

		m_renderer.init(image, dc);
		m_waterEffect.Init(m_renderer);  

		m_rectDraw.SetRect(topleft, CPoint(topleft.x + image.GetWidth(), topleft.y + image.GetHeight()));

		CWindow hwnd = static_cast<Derived*>(this)->m_hWnd;
		SetTimer(hwnd, DRAW, 40, NULL);
		SetTimer(hwnd, BLOB, 1500, NULL);    	
	}

private:
	void OnTimer(UINT_PTR id)
	{
		if (id == DRAW)
		{
			m_waterEffect.Commit();

			CClientDC dc(static_cast<Derived*>(this)->m_hWnd);
			m_renderer.Draw(m_rectDraw.TopLeft(), dc);

		}
		if (id == BLOB)
		{
			m_waterEffect.BlobOnce(
					random(m_rectDraw.left,m_rectDraw.right), 
					random(m_rectDraw.top, m_rectDraw.bottom), 
					5, 
					800, 
					m_waterEffect.m_iHpage
				);
		}
	}

	void OnMouseMove(UINT nFlags, CPoint point)
	{
		if(m_rectDraw.PtInRect(point) == TRUE)
		{
			// dibs are drawn upside down...
			point.y -= m_rectDraw.top;

			// position relative to m_rectDraw.TopLeft()
			point.x -= m_rectDraw.left;
			point.y  = m_rectDraw.Height() - point.y;

			if (nFlags & MK_LBUTTON)
				m_waterEffect.BlobOnce(point, 10, 1600);
			else
				m_waterEffect.BlobOnce(point, 5, 50);
		}
	}    
};


// for usage as a member control 
class WaterEffectCtl :  public CWindowImpl<WaterEffectCtl, CWindow>, 
						public WaterEffectImplBase<WaterEffectCtl>
{
public:
	BEGIN_MSG_MAP(WaterEffectCtl)    
        CHAIN_MSG_MAP(WaterEffectImplBase<WaterEffectCtl>)
	END_MSG_MAP()
public:
	void init(HWND hWnd, _U_STRINGorID nIDResource, const CPoint& topleft = CPoint(0,0))
	{
		Attach(hWnd);

		// call base class method
		WaterEffectImplBase<WaterEffectCtl>::init(nIDResource, topleft); 	
	}   

	void init(HWND hWnd, const CImage& image, const CPoint& topleft = CPoint(0,0))
	{
		Attach(hWnd);

		// call base class method
		WaterEffectImplBase<WaterEffectCtl>::init(image, topleft); 
	}

private:
	BOOL Attach(HWND hWnd)
	{
		//subclass
		ATLASSERT(m_hWnd==NULL);
		ATLASSERT(::IsWindow(hWnd));
		BOOL bRet = CWindowImpl<WaterEffectCtl, CWindow>::SubclassWindow(hWnd);
		
		return bRet;
	}
};