CDC中的SelectObject

1、看MSDN中的解释：

Selects an object into the device context（选择一个对象到设备上下文中去）.

[cpp] view plaincopy

1. CPen* SelectObject(  
2.    CPen* pPen   
3. );  
4. CBrush* SelectObject(  
5.    CBrush* pBrush   
6. );  
7. virtual CFont* SelectObject(  
8.    CFont* pFont   
9. );  
10. CBitmap* SelectObject(  
11.    CBitmap* pBitmap   
12. );  
13. int SelectObject(  
14.    CRgn* pRgn   
15. );  
16. CGdiObject* SelectObject(  
17.    CGdiObject* pObject  
18. );  

 

参数：

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.

 

返回值：

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.

 

返回一个指向被代替的对象的指针。这个真正指向的对象是重载于CGdiObject类的一种，比如CPen，具体以来与所使用的函数版本。

 

2、测试代码

[cpp] view plaincopy

1. void CDrawView::OnLButtonDown(UINT nFlags, CPoint point)  
2. {  
3.     // TODO: Add your message handler code here and/or call default  
4.     m_ptBegin=point;//m_ptBegin是类的成员，类型为CPoint  
5.   
6.     CView::OnLButtonDown(nFlags, point);  
7. }  
8.   
9. void CDrawView::OnLButtonUp(UINT nFlags, CPoint point)  
10. {  
11.     // TODO: Add your message handler code here and/or call default  
12.     CPen pen(PS_SOLID, 1, RGB(255, 0, 0));  
13.     CClientDC dc(this);  
14.     CPen* pOldPen=dc.SelectObject(&pen);//保存原始的CPen，即黑色的CPen  
15.     dc.MoveTo(m_ptBegin);  
16.     dc.LineTo(point);  
17.     dc.SelectObject(pOldPen);//恢复原始的CPen  
18.     dc.MoveTo(m_ptBegin);  
19.     dc.LineTo(point.x+100, point.y);  
20.     CView::OnLButtonUp(nFlags, point);  
21. }  

 

3、运行结果：

 

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