MFC(绘图与保存,孙鑫C++第十一讲笔记整理)
前面画图步骤直接上略了，因为跟第十讲的步骤是一样的，这里不再累赘
1.创建4个菜单，为其添加消息响应，用成员变量保存绘画类型。添加LButtonDown和Up消息。
2.当窗口重绘时，如果想再显示原先画的数据，则需要保存数据。为此创建一个新类来记录绘画类型和两个点。
class CGraph
{
public:
CPoint m_ptOrigin;//起点
CPoint m_ptEnd;//终点
UINT m_nDrawType;//绘画类型
CGraph();
CGraph(UINT m_nDrawType,CPoint m_ptOrigin,CPoint m_ptEnd);//此为构造函数。
virtual ~CGraph();};
然后在void CGraphicView::OnLButtonUp(UINT nFlags, CPoint point)中加入如下代码
//CGraph graph(m_nDrawType,m_ptOrigin,point);//不能用局部变量
//m_ptrArray.Add(&graph);//加入这种指针数组中
/* OnPrepareDC(&dc);//这个函数中可以重新设置窗口原点，对于滚动条中，保存数据前要调用此函数
dc.DPtoLP(&m_ptOrigin);//将设备坐标转换为逻辑坐标
dc.DPtoLP(&point);//
CGraph *pGraph=new CGraph(m_nDrawType,m_ptOrigin,point);//在堆中创建新的对象
m_ptrArray.Add(pGraph);*///加入到指针数组中
在GraphicView.h中有如下代码
CPtrArray m_ptrArray;
在OnDraw中重画时调出数据
for(int i=0;i<m_ptrArray.GetSize();i++)
3.在CView::OnPaint()调用了OnDraw(),但在void CGraphicView::OnPaint()中MFC的Wizard没有调用OnDraw(),要注意这个区别。如果你此时想调用，必须手动添加代码。 OnDraw(&dc);
4.让窗口具有滚动条的功能。
第1.将CGraphicView的头文件中的CView全部替换成CSrollView
第2.添加如下的代码
void CGraphicView::OnInitialUpdate()
{
CScrollView::OnInitialUpdate();
// TOD Add your specialized code here and/or call the base class
SetScrollSizes(MM_TEXT,CSize(800,600));//设置映射模式，设定窗口大小。OK！
}
5.坐标系的转换，此处不再详细介绍，需要时请查阅相关资料。
6.解决重绘时线跑到上面的问题。为什么会错位？因为逻辑坐标和设备坐标没有对应起来。
解决方法：
在OnLButtonDown画完图后，保存之前。调用
/* OnPrepareDC(&dc);//重新设置逻辑坐标的原点！！！
dc.DPtoLP(&m_ptOrigin);//设备坐标转化为逻辑坐标
dc.DPtoLP(&point);
CGraph *pGraph=new CGraph(m_nDrawType,m_ptOrigin,point);
m_ptrArray.Add(pGraph);*/
7.另外两种方法来保存数据。
一种是用CMetaFileDC
另一种是利用兼容DC，重绘时利用 pDC->BitBlt(0,0,rect.Width(),rect.Height(),&m_dcCompatible,0,0,SRCCOPY);
void CHuiTuBaoView::OnLButtonUp(UINT nFlags, CPoint point) {// TODO: Add your message handler code here and/or call default/*CClientDC ccdc(this);CBrush *cbrush=CBrush::FromHandle((HBRUSH)GetStockObject(NULL_BRUSH));ccdc.SelectObject(cbrush);switch(m_leixing){case 0:ccdc.SetPixel(point,RGB(0,0,0));break;case 1:ccdc.MoveTo(m_yuandian);ccdc.LineTo(point);break;case 2:ccdc.Rectangle(&CRect(m_yuandian,point));break;case 3:ccdc.Ellipse(&CRect(m_yuandian,point));break;default:break;}*///CHUATU huatu(m_leixing,m_yuandian,point);//对象的声明周期在右大括号结束之后就销毁了，所以不可行//m_carray.Add(&huatu);CHUATU *huatu=new CHUATU(m_leixing,m_yuandian,point);//使用指针，在堆栈分配了空间，与整个程序的声明周期一致，可行m_carray.Add(huatu);Invalidate();CView::OnLButtonUp(nFlags, point);}
void CHuiTuBaoView::OnDraw(CDC* pDC){CHuiTuBaoDoc* pDoc = GetDocument();ASSERT_VALID(pDoc);// TODO: add draw code for native data hereCBrush *cbrush=CBrush::FromHandle((HBRUSH)GetStockObject(NULL_BRUSH));pDC->SelectObject(cbrush);for(int i=0;i<m_carray.GetSize();++i){switch(((CHUATU*)m_carray.GetAt(i))->m_cleixing){case 0:pDC->SetPixel(((CHUATU*)m_carray.GetAt(i))->m_czhondian,RGB(255,0,0));break;case 1:pDC->MoveTo(((CHUATU*)m_carray.GetAt(i))->m_cyuandian);pDC->LineTo(((CHUATU*)m_carray.GetAt(i))->m_czhondian);break;case 2:pDC->Rectangle(&CRect(((CHUATU*)m_carray.GetAt(i))->m_cyuandian,((CHUATU*)m_carray.GetAt(i))->m_czhondian));break;case 3:pDC->Ellipse(&CRect(((CHUATU*)m_carray.GetAt(i))->m_cyuandian,((CHUATU*)m_carray.GetAt(i))->m_czhondian));break;default:break;}}}
上面使用CPtrArray来保存CHUATU的指针，那能不能使用我们熟悉的Vector动态数组来操作呢。试试便知
试验证明是可以的。
在CXXView头文件中写上
include<vector>
using namespace std;
然后定义成员变量
vector<CHUATU*>vv;
void CHuiTuBaoView::OnLButtonUp(UINT nFlags, CPoint point) {// TODO: Add your message handler code here and/or call default/*CClientDC ccdc(this);CBrush *cbrush=CBrush::FromHandle((HBRUSH)GetStockObject(NULL_BRUSH));ccdc.SelectObject(cbrush);switch(m_leixing){case 0:ccdc.SetPixel(point,RGB(0,0,0));break;case 1:ccdc.MoveTo(m_yuandian);ccdc.LineTo(point);break;case 2:ccdc.Rectangle(&CRect(m_yuandian,point));break;case 3:ccdc.Ellipse(&CRect(m_yuandian,point));break;default:break;}*///CHUATU huatu(m_leixing,m_yuandian,point);//m_carray.Add(&huatu);/*CHUATU *huatu=new CHUATU(m_leixing,m_yuandian,point);m_carray.Add(huatu);Invalidate();*/CHUATU *huatu=new CHUATU(m_leixing,m_yuandian,point);vv.push_back(huatu);Invalidate();CView::OnLButtonUp(nFlags, point);}
void CHuiTuBaoView::OnDraw(CDC* pDC){CHuiTuBaoDoc* pDoc = GetDocument();ASSERT_VALID(pDoc);// TODO: add draw code for native data hereCBrush *cbrush=CBrush::FromHandle((HBRUSH)GetStockObject(NULL_BRUSH));pDC->SelectObject(cbrush);/*for(int i=0;i<m_carray.GetSize();++i){switch(((CHUATU*)m_carray.GetAt(i))->m_cleixing){case 0:pDC->SetPixel(((CHUATU*)m_carray.GetAt(i))->m_czhondian,RGB(255,0,0));break;case 1:pDC->MoveTo(((CHUATU*)m_carray.GetAt(i))->m_cyuandian);pDC->LineTo(((CHUATU*)m_carray.GetAt(i))->m_czhondian);break;case 2:pDC->Rectangle(&CRect(((CHUATU*)m_carray.GetAt(i))->m_cyuandian,((CHUATU*)m_carray.GetAt(i))->m_czhondian));break;case 3:pDC->Ellipse(&CRect(((CHUATU*)m_carray.GetAt(i))->m_cyuandian,((CHUATU*)m_carray.GetAt(i))->m_czhondian));break;default:break;}}*/for(vector<CHUATU*>::iterator itera=vv.begin();itera!=vv.end();++itera){switch((*itera)->m_cleixing){case 0:pDC->SetPixel((*itera)->m_czhondian,RGB(255,0,0));break;case 1:pDC->MoveTo((*itera)->m_cyuandian);pDC->LineTo((*itera)->m_czhondian);break;case 2:pDC->Rectangle(&CRect((*itera)->m_cyuandian,(*itera)->m_czhondian));break;case 3:pDC->Ellipse(&CRect((*itera)->m_cyuandian,(*itera)->m_czhondian));break;}}}
可以使用很多方法解决，不要丢了我们前面学习的C++知识喔。
下面是有关GDI映射的问题，具体也可以看我的Windows32GDI映射的博客
OnPrepareDC会随时根据滚动窗口的位置来调整视口的原点
下面是一个关于设置坐标位置的例子。
手动设置滚动条
1class CXXView : public CView--->class CXXView : public CScrollView
2把cpp文件中的CView全部替换成CScrollView
3设置滚动条的属性
void SetScrollSizes( int nMapMode, SIZE sizeTotal, const SIZE& sizePage = sizeDefault, const SIZE& sizeLine = sizeDefault );
在CXXView中添加一个虚函数OnInitUpdate函数
4添加一条代码，这个函数是在调用OnDraw之前调用的
void CHuiTuBaoView::OnInitialUpdate() {CScrollView::OnInitialUpdate();// TODO: Add your specialized code here and/or call the base classSetScrollSizes(MM_TEXT,CSize(800,600));}
然后就可以显示滚动条了：
然后用老师讲的方法，可以解决坐标映射问题，上面的PPT有讲问题的现象和解决方法
void CHuiTuBaoView::OnLButtonUp(UINT nFlags, CPoint point) {// TODO: Add your message handler code here and/or call default/*CClientDC ccdc(this);CBrush *cbrush=CBrush::FromHandle((HBRUSH)GetStockObject(NULL_BRUSH));ccdc.SelectObject(cbrush);switch(m_leixing){case 0:ccdc.SetPixel(point,RGB(0,0,0));break;case 1:ccdc.MoveTo(m_yuandian);ccdc.LineTo(point);break;case 2:ccdc.Rectangle(&CRect(m_yuandian,point));break;case 3:ccdc.Ellipse(&CRect(m_yuandian,point));break;default:break;}*///CHUATU huatu(m_leixing,m_yuandian,point);//m_carray.Add(&huatu);/*CHUATU *huatu=new CHUATU(m_leixing,m_yuandian,point);m_carray.Add(huatu);Invalidate();*/CClientDC ccdc(this);OnPrepareDC(&ccdc);ccdc.DPtoLP(&m_yuandian);ccdc.DPtoLP(&point);CHUATU *huatu=new CHUATU(m_leixing,m_yuandian,point);vv.push_back(huatu);Invalidate();CScrollView::OnLButtonUp(nFlags, point);}
这样就完美解决了。
OnPaint中调用了OnprepareDC和OnDraw函数，OnprepareDC就是用来调整(设备环境)视口的
使用原文件上下文保存图像，CMetaFileDC
在OnLButtonUp中，CMetaFileDC yuanwenjian是成员变量，构造函数中Create
CBrush *cbrush=CBrush::FromHandle((HBRUSH)GetStockObject(NULL_BRUSH));yuanwenjiandc.SelectObject(cbrush);switch(m_leixing){case 0:yuanwenjiandc.SetPixel(point,RGB(0,0,0));break;case 1:yuanwenjiandc.MoveTo(m_yuandian);yuanwenjiandc.LineTo(point);break;case 2:yuanwenjiandc.Rectangle(&CRect(m_yuandian,point));break;case 3:yuanwenjiandc.Ellipse(&CRect(m_yuandian,point));break;default:break;}
在OnDraw中
void CHuiTuBaoView::OnDraw(CDC* pDC){CHuiTuBaoDoc* pDoc = GetDocument();ASSERT_VALID(pDoc);// TODO: add draw code for native data hereCBrush *cbrush=CBrush::FromHandle((HBRUSH)GetStockObject(NULL_BRUSH));pDC->SelectObject(cbrush);HMETAFILE hmetafile;hmetafile=yuanwenjiandc.Close();pDC->PlayMetaFile(hmetafile);yuanwenjiandc.Create();DeleteMetaFile(hmetafile);}//一定要关闭，否则出错
如果还想要保存原来的图画，这这样
void CHuiTuBaoView::OnDraw(CDC* pDC){CHuiTuBaoDoc* pDoc = GetDocument();ASSERT_VALID(pDoc);// TODO: add draw code for native data hereCBrush *cbrush=CBrush::FromHandle((HBRUSH)GetStockObject(NULL_BRUSH));pDC->SelectObject(cbrush);HMETAFILE hmetafile;hmetafile=yuanwenjiandc.Close();pDC->PlayMetaFile(hmetafile);yuanwenjiandc.Create();yuanwenjiandc.PlayMetaFile(hmetafile);//保存上一次绘画的图案DeleteMetaFile(hmetafile);}
CMetaFile只是保存的是绘图的命令，而不是文件
下面给打开和保存添加事件
void CHuiTuBaoView::OnFileSave() { // TODO: Add your command handler code here HMETAFILE hmetafile; hmetafile=yuanwenjiandc.Close(); CopyMetaFile(hmetafile,"meta.wmf"); yuanwenjiandc.Create(); DeleteMetaFile(hmetafile);}void CHuiTuBaoView::OnFileOpen() {// TODO: Add your command handler code hereHMETAFILE hmetafile;hmetafile=GetMetaFile("meta.wmf");yuanwenjiandc.PlayMetaFile(hmetafile);DeleteMetaFile(hmetafile);Invalidate();}
使用另外一种方法保存，兼容DC
在OnLButtonUp中
CBrush *cbrush=CBrush::FromHandle((HBRUSH)GetStockObject(NULL_BRUSH));CClientDC ccdc(this);if(!compatibledc){compatibledc.CreateCompatibleDC(&ccdc);CRect rect;GetClientRect(&rect);CBitmap bitmap;bitmap.CreateCompatibleBitmap(&ccdc,rect.Width(),rect.Height());compatibledc.SelectObject(&bitmap);compatibledc.SelectObject(cbrush);compatibledc.BitBlt(0,0,rect.Width(),rect.Height(),&ccdc,0,0,SRCCOPY);//兼容位图跟普通不一样}yuanwenjiandc.SelectObject(cbrush);switch(m_leixing){case 0:compatibledc.SetPixel(point,RGB(0,0,0));break;case 1:compatibledc.MoveTo(m_yuandian);compatibledc.LineTo(point);break;case 2:compatibledc.Rectangle(&CRect(m_yuandian,point));break;case 3:compatibledc.Ellipse(&CRect(m_yuandian,point));break;default:break;}
OnDraw中
CRect rect;GetClientRect(&rect);pDC->BitBlt(0,0,rect.Width(),rect.Height(),&compatibledc,0,0,SRCCOPY);
