MFC截图工具（不断更新）

基于MFC 开发的截图工具
文件名:Draw
创建单个文档，MFC标准
一.将视图显示
			1.MainFrm.cpp 中
			int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
							SetMenu(NULL);  去掉菜单
							CBRS_BOTTOM  将工具栏现实在下面
							将状态显示的代码去掉
			BOOL CMainFrame::PreCreateWindow(CREATESTRUCT& cs)
			cs.style=WS_POPUP;
			2.Draw.cpp(App类)
			BOOL CDrawApp::InitInstance()
			m_pMainWnd->ShowWindow(SW_MAXIMIZE);
			3.添加按ESC退出界面
			在类视图CDrawView添加消息OnKeyDown
			if(nChar ==VK_ESCAPE)
			{
				::PostQuitMessage(0);
			}
			4.在资源视图新创建一个ToolBar，并添加消息处理
			在CDrawView.h
				afx_msg void OnQuit();//退出
				afx_msg void OnCureve();
				afx_msg void OnLine();
				afx_msg void OnEllipse();
				afx_msg void OnRect();
				afx_msg void OnTriangle();
				afx_msg void OnFill();
				afx_msg void OnColor();
				afx_msg void OnSave();
			在CDrawView.cpp
				ON_COMMAND(ID_QUIT,&CMainFrame::OnQuit)
				ON_COMMAND(ID_CURVE,&CMainFrame::OnCureve)
				ON_COMMAND(ID_ONLINE,&CMainFrame::OnLine)
				ON_COMMAND(ID_ELS,&CMainFrame::OnEllipse)
				ON_COMMAND(ID_RECT,&CMainFrame::OnRect)
				ON_COMMAND(ID_TRA,&CMainFrame::OnTriangle)
				ON_COMMAND(ID_RECT,&CMainFrame::OnRect)
				ON_COMMAND(ID_FILL,&CMainFrame::OnFill)
				ON_COMMAND(ID_SAVE,&CMainFrame::OnSave)
				ON_COMMAND(ID_COLOR,&CMainFrame::OnColor)
			5.将桌面图片显示到视图上
			在CMainFram.h
				list m_lstDesktopBmp;//每次画一笔都要装到链表里
				int m_nScreenX;
				int m_nScreenY;
			在CMainFrame.cpp
			CMainFrame::CMainFrame()
			{
				m_nScreenX=GetSystemMetrics(SM_CXSCREEN);
				m_nScreenY=GetSystemMetrics(SM_CYSCREEN);
				//获取桌面的图片
				CWindowDC m_dcDesktop(GetDesktopWindow());
				//保存这张图片
				CBitmap *bitmap=new CBitmap;
				bitmap->CreateCompatibleBitmap(&m_dcDesktop,m_nScreenX,m_nScreenY);
				//创建一个DC
				CDC cdc;
				cdc.CreateCompatibleDC(&m_dcDesktop);
				cdc.SelectObject(bitmap);
				//把桌面的图片放到cdc里
				cdc.BitBlt(0,0,m_nScreenX,m_nScreenY,&m_dcDesktop,0,0,SRCCOPY);
				//把bitmap放到链表里
				m_lstDesktopBmp.push_back(bitmap);
			}
			在CDrawView.h中
			void CDrawView::OnDraw(CDC* /*pDC*/)
				//  把 链表的  尾节点的图片 放到 view 上
			CMainFrame* frame = (CMainFrame*)AfxGetMainWnd();
			
			CClientDC dc(this);  //  窗口
			
			CDC cdc;               //  装 链表 尾节点里的 图片
			cdc.CreateCompatibleDC(&dc);
			cdc.SelectObject(frame->m_lstDesktopBmp.back());    // 把 链表 尾节点里的 图片 装到 cdc

			dc.BitBlt(0,0,frame->m_nScreenX,frame->m_nScreenY,&cdc,0,0,SRCCOPY);
二.画图
            1,鼠标左键抬起保存图片到链表尾部(m_nDrawStyle判断画的是什么图形,m_nbDrawFlag判断是否画图,要在构造函数初始化)
			void CDrawView::OnLButtonUp(UINT nFlags, CPoint point)
			{
				// TODO: 在此添加消息处理程序代码和/或调用默认值
				m_bDrawFlag=false;
				//保存图片到链表
				CMainFrame *frame=(CMainFrame*)AfxGetMainWnd();
				CClientDC dc(this);

				CBitmap *bitmap=new CBitmap;
				bitmap->CreateCompatibleBitmap(&dc,frame->m_nScreenX,frame->m_nScreenY);

				CDC cdc;
				cdc.CreateCompatibleDC(&dc);
				cdc.SelectObject(bitmap);
				cdc.BitBlt(0,0,frame->m_nScreenX,frame->m_nScreenY,&dc,0,0,SRCCOPY);
				frame->m_lstDesktopBmp.push_back(bitmap);
				CView::OnLButtonUp(nFlags, point);
			}
			2.画图
			void CDrawView::OnMouseMove(UINT nFlags, CPoint point)
			{
				// TODO: 在此添加消息处理程序代码和/或调用默认值
				if(m_bDrawFlag==true)
				{
					CMainFrame *frame=(CMainFrame*)AfxGetMainWnd();
					CClientDC dc(this);
					//创建兼容性  DC
					//拿链表的最后一张图片刷新
					CDC cdc;
					cdc.CreateCompatibleDC(&dc);
					cdc.SelectObject(frame->m_lstDesktopBmp.back());
					//创建一个位图Bitmap
					//复制链表尾结点的图片
					CBitmap bitmap;
					bitmap.CreateCompatibleBitmap(&dc,frame->m_nScreenX,frame->m_nScreenY);

					CDC tempdc;
					tempdc.CreateCompatibleDC(&dc);
					tempdc.SelectObject(bitmap);
					tempdc.BitBlt(0,0,frame->m_nScreenX,frame->m_nScreenY,&cdc,0,0,SRCCOPY);
					//不能传输dc到tempdc
					//看画什么图形
					switch (m_nDrawStyle)
					{
					case ID_CURVE:
						dc.MoveTo(m_pointMouseDown.x,m_pointMouseDown.y);
						dc.LineTo(point.x,point.y);
						m_pointMouseDown=point;
						break;
					case ID_ONLINE:
						//不能用cdc画图，因为cdc就是链表的最后一张位图，更改cdc就是更改最后一张图片
						//所以在tempdc上面画图
						//移动一次创建的Bitmap就删除，没有改变
						tempdc.MoveTo(m_pointMouseDown.x,m_pointMouseDown.y);
						tempdc.LineTo(point.x,point.y);
						dc.BitBlt(0,0,frame->m_nScreenX,frame->m_nScreenY,&tempdc,0,0,SRCCOPY);
						break;
					case ID_ELS:
						tempdc.SelectStockObject(NULL_BRUSH);
						tempdc.Ellipse(m_pointMouseDown.x,m_pointMouseDown.y,point.x,point.y);
						dc.BitBlt(0,0,frame->m_nScreenX,frame->m_nScreenY,&tempdc,0,0,SRCCOPY);
						break;
					case ID_RECT:
						tempdc.Rectangle(m_pointMouseDown.x,m_pointMouseDown.y,point.x,point.y);
						dc.BitBlt(0,0,frame->m_nScreenX,frame->m_nScreenY,&tempdc,0,0,SRCCOPY);
						break;
					case ID_TRA:
						tempdc.SelectStockObject(NULL_BRUSH);
						POINT rect[3]={{(point.x+m_pointMouseDown.x)/2,m_pointMouseDown.y},{m_pointMouseDown.x,point.y},{point.x,point.y}};
						tempdc.Polygon(rect,3);
						dc.BitBlt(0,0,frame->m_nScreenX,frame->m_nScreenY,&tempdc,0,0,SRCCOPY);
						break;
					}
				}
				CView::OnMouseMove(nFlags, point);
			}