SelectObject()函數__MFC用戶端

SelectObject 
把一個對象(位元影像、畫筆、畫刷等)選入指定的裝置描述表。新的對象代替同一類型的老對象。

HGDIOBJ  SelectObject(    HDC  hdc,          // handle to DC    HGDIOBJ  hgdiobj   // handle to object );

 

參數 hdc 裝置描述表控制代碼(要載入的裝置描述表控制代碼) hgdiobj 選擇要載入的對象的控制代碼

但該對象的控制代碼必須使用以下函數建立才有效：

Bitmap(位元影像)          CreateBitmap, CreateBitmapIndirect, 
                            CreateCompatibleBitmap, CreateDIBitmap, 
                            CreateDIBSection 
Brush(畫刷)           CreateBrushIndirect, eateDIBPatternBrush,  
                            CreateDIBPatternBrushPt, CreateHatchBrush,  
                            CreatePatternBrush, CreateSolidBrush 
Font(字型)              CreateFont, CreateFontIndirect

Pen(畫筆)               CreatePen, CreatePenIndirect

Region(地區)             CombineRgn, CreateEllipticRgn,  
                               CreateEllipticRgnIndirect,  
                               CreatePolygonRgn, CreateRectRgn,  
                               CreateRectRgnIndirect 
傳回值：如果選擇對象不是地區並且函數執行成功，那麼傳回值是被取代的對象的控制代碼；如果選擇對象是地區並且函數執行成功，返回如下一值；

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1、看MSDN中的解釋：

Selects an object into the device context（選擇一個對象到裝置上下文中去）.

[cpp]  view plain copy CPen* SelectObject(      CPen* pPen    );   CBrush* SelectObject(      CBrush* pBrush    );   virtual CFont* SelectObject(      CFont* pFont    );   CBitmap* SelectObject(      CBitmap* pBitmap    );   int SelectObject(      CRgn* pRgn    );   CGdiObject* SelectObject(      CGdiObject* pObject   );  

 

參數： pPen

A pointer to a CPen object to be selected. pBrush

A pointer to a CBrush object to be selected. pFont

A pointer to a CFont object to be selected. pBitmap

A pointer to a CBitmap object to be selected. pRgn

A pointer to a CRgn object to be selected. pObject

A pointer to a CGdiObject object to be selected.

 

傳回值：

A pointer to the object being replaced. This is a pointer to an object of one of the classes derived fromCGdiObject, such as CPen, depending on which version of the function is used.

 

返回一個指向被代替的對象的指標。這個真正指向的對象是重載於CGdiObject類的一種，比如CPen，具體以來與所使用的函數版本。

 

2、測試代碼

[cpp]  view plain copy void CDrawView::OnLButtonDown(UINT nFlags, CPoint point)   {       // TODO: Add your message handler code here and/or call default       m_ptBegin=point;//m_ptBegin是類的成員，類型為CPoint          CView::OnLButtonDown(nFlags, point);   }      void CDrawView::OnLButtonUp(UINT nFlags, CPoint point)   {       // TODO: Add your message handler code here and/or call default       CPen pen(PS_SOLID, 1, RGB(255, 0, 0));       CClientDC dc(this);       CPen*&n