位图操作与GDI对象管理

来源：萌宠菠菠乐园时间：2024-12-21 17:57 更新：2024-12-25 02:10

CMemDC的功能：

最新推荐文章于 2021-03-08 16:43:36 发布

qiukapi 于 2018-10-29 20:39:58 发布

a)通过资源ID加载进程内位图：BOOL LoadBitmap(UINT nBitmap, CDC* pDC = NULL);
B)通过文件名加载进程外位图：BOOL LoadBitmap(LPCSTR szFile, CDC* pDC = NULL);
C)在构造对象时加载进程内位图：CMemDC(UINT nBitmap, CDC* pDC = NULL);
D)在构造对象时加载进程外位图：CMemDC(LPCSTR szFile, CDC* pDC = NULL);
E)获取位图信息：int GetWidth();和int GetHeigth();
F)摧毁时检查和处理GDI泄露问题(在析构函数中调用)：BOOL DeleteDC();
G)创建一个指定高宽的空白位图：BOOL Create(int cx, int cy, CDC* pDC = NULL);

#pragma once

class My_CMemDC : public CDC
{
   CSize m_size;
public:
   My_CMemDC()
   {
       m_size.cx = m_size.cy = 0;
   }
   My_CMemDC(UINT nBitmap, CDC * pDC = NULL)
   {
       LoadBitmap(nBitmap, pDC);
   }
   My_CMemDC(CString szFile, CDC *pDC = NULL)
   {
       LoadBitmap(szFile, pDC );
   }
   ~My_CMemDC()
   {
       DeleteDC();
   }
   int GetWidth(){ return m_size.cx; }
   int GetHeight(){ return m_size.cy; }
   BOOL DeleteDC()
   {
       if (!GetSafeHdc())
           return FALSE;
       CBitmap *pBitmap = GetCurrentBitmap();
       if (pBitmap)
           pBitmap->DeleteObject();
       return CDC::DeleteDC();
   }
   BOOL Create(int cx, int cy, CDC* pDC = NULL)
   {//创建空白位图
       CBitmap bmp;
       bmp.CreateCompatibleBitmap(pDC, cx, cy);
       CreateCompatibleDC(pDC);
       SelectObject(&bmp);
       return TRUE;
   }
   BOOL LoadBitmap(UINT nBitmap, CDC * pDC = NULL)
   {
       CBitmap bmp;
       if (!bmp.LoadBitmap(nBitmap))
           return FALSE;
       BITMAP bm;
       bmp.GetBitmap(&bm);
       m_size.cx = bm.bmWidth;
       m_size.cy = bm.bmHeight;
       CreateCompatibleDC(pDC);
       SelectObject(&bmp);
       return TRUE;
   }
   BOOL LoadBitmap(CString szFile, CDC *pDC = NULL)
   {
       HBITMAP hBitmap = (HBITMAP)LoadImage(NULL, szFile, IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
       if (!hBitmap)
           return FALSE;
       //CBitmap *pBitmap = CBitmap::FromHandle(hBitmap);
       BITMAP bm;
       //pBitmap->GetBitmap(&bm);
       GetObject(hBitmap, sizeof(bm), &bm);
       m_size.cx = bm.bmWidth;
       m_size.cy = bm.bmHeight;
       CreateCompatibleDC(pDC);
       SelectObject(hBitmap);
       return TRUE;
   }
};