猎豹MFC--备用对象和取消选定 画直尺
右击view视图 属性 Onpaint消息
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155208224-1500149240.png)
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155208490-377829640.png)
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155209209-242490667.png)
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155209553-689485848.png)
![](4476e19b-4125-4dc0-9f1e-2f1e13b0f9bc_files/e0853516-8f87-46a3-ae64-f90da3af5f86.png)
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155239428-1195517572.png)
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155239849-2014192459.png)
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155240443-1497521373.png)
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155240959-1771354520.png)
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155241224-26728793.png)
![](4476e19b-4125-4dc0-9f1e-2f1e13b0f9bc_files/2c7f85c2-62ea-448c-b7fe-6318a625c071.png)
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155208224-1500149240.png)
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155208490-377829640.png)
备用对象:
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155209209-242490667.png)
备用对象创建画笔和画刷 法3
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155209553-689485848.png)
以上是用堆栈变量实现,下面用指针实现:
CPen * pPen =new CPen(PS_SOLID,1,RGB(0,255,0));
CPen * pOldPen = dc.SelectObject(pPen);//把pPen给dc并用指针保存旧笔,
dc.Ellipse(0,0,100,100);
dc.SelectObject(pOldPen);//把旧的笔重新选入dc,新的笔也就取消了或者说选出 了
delete pPen;
改变坐标为改变映射模式
DC默认坐标垂直向下是正。改变映射模式 即改为垂直向下是负的
![](4476e19b-4125-4dc0-9f1e-2f1e13b0f9bc_files/e0853516-8f87-46a3-ae64-f90da3af5f86.png)
画直尺
注意对齐方式 阴影处设置:
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155239428-1195517572.png)
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155239849-2014192459.png)
到时第二行 除以100 转换为 英寸单位
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155240443-1497521373.png)
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155240959-1771354520.png)
![](https://images2015.cnblogs.com/blog/751322/201603/751322-20160320155241224-26728793.png)
![](4476e19b-4125-4dc0-9f1e-2f1e13b0f9bc_files/2c7f85c2-62ea-448c-b7fe-6318a625c071.png)