VC下利用Picture控件实现png图片按钮（鼠标初始、按下、松开、获得焦点四种状态）

/************************************************************
* 类名:CPngStatic
* 作用：在vc dialog中使用picture控件显示png图片，并相应鼠标
*       消息，可做picture button使用
* 注意：如果有背景时，背景控件必须在pngButton控件之下（tab=1）
* 原理：使用控件背景覆盖法实现png图片的重画和透明效果
*************************************************************/
#ifndef _PNGBUTTON_ZZZILI
#define _PNGBUTTON_ZZZILI
#include "stdafx.h"
class CMyImage:public Image
{
public:
 CMyImage(UINT uID)
 {
  // 初始化 Image 成员变量
  nativeImage = NULL;
  lastResult = InvalidParameter;
  // 查找图片资源
  HINSTANCE hInst =  GetModuleHandle(NULL);
  HRSRC hRsrc = FindResource(hInst, MAKEINTRESOURCE(uID), _T("PNG"));
  if (!hRsrc) {
   return;
  }
  // 加载资源并获取其指针
  HGLOBAL hMemRsrc = LoadResource(hInst, hRsrc);
  BYTE * pMemRsrc = (BYTE *)LockResource(hMemRsrc);
  // 为流分配全局内存空间
  size_t sizeRsrc = SizeofResource(hInst, hRsrc);
  HGLOBAL hMemStrm = GlobalAlloc(GMEM_FIXED, sizeRsrc);
  if (!hMemStrm) {
   return;
  }
  // 拷贝图片资源到全局内存空间中
  BYTE * pMemStrm = (BYTE *)GlobalLock(hMemStrm);
  memcpy(pMemStrm, pMemRsrc, sizeRsrc);
  // 使用图片资源流构造 Image 对象
  IStream * pStrm = NULL;
  CreateStreamOnHGlobal(hMemStrm, TRUE, &pStrm);
  lastResult = DllExports::GdipLoadImageFromStream(pStrm, &nativeImage);
  pStrm->Release();
 } 
}; 
class CPngStatic : public CStatic
{
public:
 CPngStatic();
 ~CPngStatic();
 void SetInitPngPic(int id);//设置初始png图片
 void SetClickDownPngPic(int id);//设置鼠标左键按下时png图片
 void SetClickUpPngPic(int id);//设置鼠标左键松开时png图片
 void SetMouseOnPngPic(int id);//设置鼠标在控件上时png图片
private:
 RECT rp,lp;
 CDC *parentCDC;
 CDC* pFgndMemDC;
 BOOL isGetBj;
 CString pngFile;
 RECT m_rect;
 RECT m_bjRect;
 Image *m_image;
private:
 CDC* GetParentBkgnd(CWnd *pWnd, CPoint ptDrawStart, int nWidth,int nHeight);
 CDC* CreateMixDC(CDC* pParentMemDC, Image* image);
 void AlphaGradientDraw(CWnd* pWnd, CDC* pFgndMemDC, CDC* pBkgndMemDC,CPoint ptDrawStart, int nWidth, int nHeight, int nTransparence);
private:
 Image *ClickDownImage;
 Image *ClickUpImage;
 Image *MouseOnImage;
 Image *InitImage;
 BOOL isMouseOnPic;
 BOOL isSetClickDownImage;
 BOOL isSetClickUpImage;
 BOOL isSetMouseOnImage;
 BOOL isSetInitImage;
private:
 void SetBj();
 void SetBitmap(Image *image);
public:
 DECLARE_MESSAGE_MAP()
 afx_msg void OnPaint();
 afx_msg BOOL OnSetCursor(CWnd* pWnd, UINT nHitTest, UINT message);
 afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
 afx_msg void OnLButtonUp(UINT nFlags, CPoint point);
 afx_msg void OnMouseLeave();
 afx_msg void OnMouseMove(UINT nFlags, CPoint point);
};
#endif