如何清除cclientdc完成的图纸？ [英] How can I clear drawings done by cclientdc?

问题描述

大家好，

i我在MFC vc ++上用拨号做图纸。



i我根据我得到的不同输入绘制线条从序列号。



现在我想在我得到另一个输入时清除图纸。



< b>我尝试了什么：

Hello people,
i am doing drawings on dialof in MFC vc++.

i am drawing lines as per the different inputs i am getting from the serial.

now i want to clear the drawings when i get another input.

What I have tried:

CClientDC dc(GetDlgItem(IDC_STATICDISPLAY));

CPen lDot(PS_DASH, 2, RGB(255, 255, 255));

dc.SelectObject(&lDot);
	dc.Rectangle(a,b,c,d);

这里a，b，c，d是我的不同输入，我从串口通信。

每个输入我想要清除旧图纸并用新数据绘制新行。



和

Here a,b,c,d are my different inputs which i am getting from the serial communication.
at each input i want to clear the older drawings and draw a new lines with new data.

And

GetDlgItem(IDC_STATICDISPLAY)

是我在对话框中绘制线条的组框。

is the group box in which i am drawing lines in dialog.

推荐答案

GetDlgItem（IDC_STATICDISPLAY） - > ;无效（true）;



这将导致组框被删除并重新绘制。擦除意味着将为控件绘制默认背景。

GetDlgItem(IDC_STATICDISPLAY)->Invalidate( true );

That will cause the group box to be erased and redrawn. Erased means the default background will be drawn for the control.

如果控件是完全所有者绘制的，您应该在第一次绘制调用时使用带有bckground颜色的FillRect。



我建议您将控件的Windows控件和其他常量对象（如笔）存储为成员变量，以提高性能。

If the control is completly owner drawn that you should use FillRect with your bckground color at first draw call.

And I would suggest that you store the Windows-handle of the control and other constant objects (like the pen) as member variables to improve performance.

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