ReleaseDC 和 DeleteDC 的区别

技术文章 11个月前 完美者
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简单的说,GetDC和ReleaseDC的调用配对,CreateDC和DeleteDC的调用配对。

GetDC是从窗口获取现有的DC,而CreateDC是创建DC,所以ReleaseDC和DeleteDC的作用一个是释放,一个是销毁。

 

叁考:https://blog.csdn.net/business122/article/details/9612299

 

API原文

intReleaseDC(CDC*pDC);

Return Value

Nonzero if successful; otherwise 0.

Parameters

pDC

Identifies the device context to be released.

Remarks

Releases a device context, freeing it for use by other applications. The effect of the ReleaseDCmember function depends on the device-context type.

The application must call the ReleaseDCmember function for each call to the member function and for each call to the member function.

这里最后一句提到了

The application must call the ReleaseDCmember function for each call to the member function and for each call to the member function.

所有调用GetWindowDC和GetDC获取的DC对象必须使用ReleaseDC来释放

 

然后又查看了DeleteDC的API内容

CDC::DeleteDC

virtualBOOLDeleteDC();

Return Value

Nonzero if the function completed successfully; otherwise 0.

Remarks

In general, do not call this function; the destructor will do it for you. The DeleteDCmember function deletes the Windows device contexts that are associated with m_hDCin the current CDCobject. If this CDCobject is the last active device context for a given device, the device is notified and all storage and system resources used by the device are released.

An application should not call DeleteDCif objects have been selected into the device context. Objects must first be selected out of the device context before it it is deleted.

An application must not delete a device context whose handle was obtained by calling . Instead, it must call to free the device context. The and classes are provided to wrap this functionality.

The DeleteDCfunction is generally used to delete device contexts created with , , or .

 

看了最后一句就可以区分什么时候调用ReleaseDC了

就是GetDC或GetWindowDC获得的DC要使用ReleaseDC释放

Create得到的DC要用Delete释放

这样就不会出现内存泄露事情了

ReleaseDC 和 DeleteDC 的区别

标签:简单   sse   select   创建   you   The   col   gen   success   

原文地址:https://www.cnblogs.com/personnel/p/14260887.html

版权声明:完美者 发表于 2021-01-13 10:44:38。
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