MFC:: GDI

GDI

1.01 通过HDC获得CDC指针

void CDemoDlg::OnTest()
{
	//获得当前DC的句柄
	HDC hDC = ::GetDC(m_hWnd);

	//通过HDC获得CDC指针
	CDC* pDC = CDC::FromHandle(hDC);

	//输出文本
	pDC->SetBkMode(TRANSPARENT);
	pDC->SetTextAlign(TA_CENTER);
	CRect rect;
	GetClientRect(rect);
	pDC->TextOut(rect.Width() / 2, 10, _T("Hello World!"));
}

1.02 创建屏幕DC

void CDemoDlg::OnTest() 
{
	CDC* pDC = new CDC();

	//创建屏幕DC
	pDC->CreateDC(_T("DISPLAY"), NULL, NULL, NULL);

	//设置背景模式
	pDC->SetBkMode(TRANSPARENT);
	//设置文本对齐方式
	pDC->SetTextAlign(TA_CENTER);

	//获得屏幕长度和高度
 	int cx = GetSystemMetrics(SM_CXSCREEN);
 	int cy = GetSystemMetrics(SM_CYSCREEN);

	//在屏幕输出文本
	pDC->TextOut(cx / 2, cy / 2 - 40, _T("Hello World!"));

	delete pDC;
}

1.03 选择预定义的GDI对象

void CDemoView::OnDraw(CDC* pDC)
{
	//选择画刷
	pDC->SelectStockObject(GRAY_BRUSH);
	//选择画笔
	pDC->SelectStockObject(BLACK_PEN);
	//选择字体
	pDC->SelectStockObject(ANSI_FIXED_FONT);

	CRect rect(0, 0, 100, 100);

	//设置背景模式
	pDC->SetBkMode(TRANSPARENT);

	//绘制椭圆
	pDC->Ellipse(rect);

	//输出文本
	pDC->TextOut(rect.right, rect.bottom, _T("Hello World!"));
}

1.04 获取设备CDC

//获得按钮DC
CDC* pDC = pButton->GetDC();
//获得文本大小
CSize size = pDC->GetTextExtent(strText);

1.05 在长文本末端显示省略号

void CDemoView::OnDraw(CDC* pDC)
{
	CString strText = _T("This a long string");
	CRect rect(10, 10, 100, 30);

	//输出文本，在长文本末端显示省略号
	pDC->DrawText(strText, rect, DT_LEFT | DT_END_ELLIPSIS);
}

1.06 设置文本的对齐方式

void CDemoView::OnDraw(CDC* pDC)
{
	CRect rect;
	GetClientRect(rect);

	pDC->MoveTo(rect.Width() / 2, 0);
	pDC->LineTo(rect.Width() / 2, rect.Height() / 2);
	pDC->MoveTo(0, 3 * rect.Height() / 4);
	pDC->LineTo(rect.Width(), 3 * rect.Height() / 4);

	//设置透明背景
	pDC->SetBkMode(TRANSPARENT);

	//设置左对齐
	pDC->SetTextAlign(TA_LEFT);
	pDC->TextOut(rect.Width() / 2, 0, _T("TA_LEFT"));

	//设置中间对齐
	pDC->SetTextAlign(TA_CENTER);
	pDC->TextOut(rect.Width() / 2, 25, _T("TA_CENTER"));

	//设置右对齐
	pDC->SetTextAlign(TA_RIGHT);
	pDC->TextOut(rect.Width() / 2, 50, _T("TA_RIGHT"));

	//设置基线对齐
	pDC->SetTextAlign(TA_CENTER | TA_BASELINE);
	pDC->TextOut(rect.Width() / 4, 3 * rect.Height() / 4, _T("TA_BASELINE"));

	//设置上对齐
	pDC->SetTextAlign(TA_CENTER | TA_TOP);
	pDC->TextOut(rect.Width() / 2, 3 * rect.Height() / 4, _T("TA_TOP"));

	//设置下对齐
	pDC->SetTextAlign(TA_CENTER | TA_BOTTOM);
	pDC->TextOut(3 * rect.Width() / 4, 3 * rect.Height() / 4, _T("TA_BOTTOM"));
}

1.07 设置背景模式

void CDemoView::OnDraw(CDC* pDC)
{
	//设置灰色背景
	pDC->SelectStockObject(GRAY_BRUSH);
	CRect rect;
	GetClientRect(rect);
	pDC->Rectangle(rect);

	//设置不透明背景
	pDC->SetBkMode(OPAQUE);
	pDC->TextOut(10, 10, _T("Hello World!"));

	//设置透明背景
	pDC->SetBkMode(TRANSPARENT);
	pDC->TextOut(10, 50, _T("Hello World!"));
}

1.07 绘制多变形

CRect rect;
GetClientRect(rect);
rect.InflateRect(-50, -50, -50, -50);

//绘制直线
pDC->MoveTo(rect.left, rect.top);
pDC->LineTo(rect.right, rect.bottom);

//绘制矩形
pDC->Rectangle(rect);

//绘制圆形或椭圆形
pDC->Ellipse(rect);

//绘制扇形
 pDC->Pie(rect,
 	CPoint(rect.right, rect.CenterPoint().y),
 	CPoint(rect.CenterPoint().x, rect.right));

//绘制多边形
CPoint point[4];
point[0].x = rect.left + rect.Width() / 2;
point[0].y = rect.top;
point[1].x = rect.right;
point[1].y = rect.top + rect.Height() / 2;
point[2].x = point[0].x;
point[2].y = rect.bottom;
point[3].x = rect.left;
point[3].y = point[1].y;
pDC->Polygon(point, 4);

//绘制圆角矩形
pDC->RoundRect(rect, CPoint(50, 50));

1.08 设置画笔

void CDemoView::OnSetDashStyle()
{
	m_nStyle = PS_DASH;
	m_Pen.DeleteObject();
	//创建画笔
	m_Pen.CreatePen(m_nStyle, m_nWidth, m_crColor);
}

1.09 画刷

COLORREF crColor = RGB(255, 0, 0);
//创建实线画刷
m_Brush.CreateSolidBrush(crColor);

void CDemoView::OnCreateSolidBrush() 
{
	m_nType = 0;
	m_Brush.DeleteObject();
	COLORREF crColor = RGB(255, 0, 0);
	//创建实线画刷
	m_Brush.CreateSolidBrush(crColor);
}

void CDemoView::OnCreateHatchBrush() 
{
	m_nType = 1;
	m_Brush.DeleteObject();
	COLORREF crColor = RGB(255, 0, 0);
	// 创建阴影线画刷
	m_Brush.CreateHatchBrush(HS_CROSS, crColor);
}

void CDemoView::OnCreatePatternBrush()
{
	m_nType = 3;
	m_Brush.DeleteObject();
	//创建图案
	WORD HatchBits[8] = {0x11, 0x22, 0x44, 0x88, 0x11, 0x22, 0x44, 0x88};
	//创建位图
	CBitmap bmp;
	bmp.CreateBitmap(8, 8, 1, 1, HatchBits);
	//创建位图图案画刷
	m_Brush.CreatePatternBrush(&bmp);
}

void CDemoView::OnLButtonDown(UINT nFlags, CPoint point)
{
	CDC* pDC = GetDC();
	//选择画笔
	CPen* pOldPen = (CPen*)pDC->SelectStockObject(NULL_PEN);
	//选择画刷
	CBrush* pOldBrush = (CBrush*)pDC->SelectObject(&m_Brush);
	pDC->Ellipse(point.x - 25, point.y - 25, point.x + 25, point.y + 25);
	//恢复画笔
	pDC->SelectObject(pOldPen);
	//恢复画刷
	pDC->SelectObject(pOldBrush);
	CView::OnLButtonDown(nFlags, point);
}

1.10 使用字体

void CDemoView::OnDraw(CDC* pDC)
{
	//初始坐标
	CPoint point(10, 10);

	for (int n = 0; n < 10; n++)
	{
		int nHeight = n * 5 + 10;

		//创建字体
		CFont font;
		font.CreateFont(
			nHeight,
			0,
			0,
			0,
			FW_NORMAL,
			FALSE,
			FALSE,
			0,
			ANSI_CHARSET,
			OUT_DEFAULT_PRECIS,
			CLIP_DEFAULT_PRECIS,
			DEFAULT_QUALITY,
			DEFAULT_PITCH | FF_SWISS,
			_T("Arial"));

		//将字体选入设备环境
		CFont* pOldFont = pDC->SelectObject(&font);

		pDC->TextOut(point.x, point.y, _T("Hello World!"));

		pDC->SelectObject(pOldFont);

		point.y += nHeight;
	}
}

1.11 显示位图资源

void CDemoView::OnDraw(CDC* pDC)
{
	//加载位图
	CBitmap bitmap;
	if (!bitmap.LoadBitmap(IDB_BITMAP))
	{
		return;
	}

	//获得位图信息
	BITMAP bmpinfo;
	bitmap.GetBitmap(&bmpinfo);

	//创建内存DC
	CDC MemDC;
	MemDC.CreateCompatibleDC(pDC);

	//将位图装入内存设备环境
	CBitmap* pOldBitmap = MemDC.SelectObject(&bitmap);

	//获得客户区矩形
	CRect rect;
	GetClientRect(&rect);

	//将位图从内存设备环境拷贝到屏幕设备环境
	pDC->BitBlt(
		rect.left + (rect.Width() - bmpinfo.bmWidth) / 2,
		rect.top + (rect.Height() - bmpinfo.bmHeight) / 2,
		bmpinfo.bmWidth, 
		bmpinfo.bmHeight, 
		&MemDC, 
		0, 
		0, 
		SRCCOPY);

	//恢复原来的位图
	MemDC.SelectObject(pOldBitmap);
}

1.12 显示位图文件

void CDemoView::OnDraw(CDC* pDC)
{
	//加载位图
	HBITMAP hBitmap = (HBITMAP)::LoadImage(AfxGetInstanceHandle(), _T("Demo.BMP"),
		IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE | LR_CREATEDIBSECTION);
	if (hBitmap == NULL)
	{
		return;
	}
	CBitmap* pBitmap = CBitmap::FromHandle(hBitmap);

 	//获得位图信息
 	BITMAP bmpinfo;
 	pBitmap->GetBitmap(&bmpinfo);

	//创建内存DC
	CDC MemDC;
	MemDC.CreateCompatibleDC(pDC);

	//将位图装入内存设备环境
	CBitmap* pOldBitmap = MemDC.SelectObject(pBitmap);

	//获得客户区矩形
	CRect rect;
	GetClientRect(&rect);

	//将位图从内存设备环境拷贝到屏幕设备环境
	pDC->StretchBlt(
		rect.left, 
		rect.top, 
		rect.Width(), 
		rect.Height(), 
		&MemDC, 
		0, 
		0,
		bmpinfo.bmWidth,
		bmpinfo.bmHeight,
		SRCCOPY);
	//恢复原来的位图
	MemDC.SelectObject(pOldBitmap);
}

1.13 进行坐标映射

void CDemoView::OnDraw(CDC* pDC)
{
	//获得客户区大小
	CRect rcClient;
	GetClientRect(rcClient);

	//设置坐标映射模式
	pDC->SetMapMode(MM_ANISOTROPIC);

	//设置窗口（逻辑坐标）的原点
	pDC->SetWindowOrg(0, 0);
	//设置窗口（逻辑坐标）的范围
	pDC->SetWindowExt(800, 800);

	//设置视口（设备坐标）的原点
	pDC->SetViewportOrg(rcClient.right / 2, rcClient.bottom / 2);
	//设置视口（设备坐标）的范围
	pDC->SetViewportExt(rcClient.right, rcClient.bottom);
	pDC->Ellipse(-400, -400, 400, 400);
}

1.14 获得其他程序的图标

void CDemoDlg::OnTest()
{
	//获得写字板程序图标
	HICON hIcon=::ExtractIcon(AfxGetInstanceHandle(), _T("NotePad.exe"), 0);
	CDC* pDC = GetDC();
	if (hIcon != NULL)
	{
		//绘制图标
	   pDC->DrawIcon(15, 50, hIcon);
	}
	//销毁图标
	DestroyIcon(hIcon);
}