Draw some simple graphics with MFC

Catalog

      One 、 Draw a straight line

      Change the brush style

      Two 、 Use the brush to draw a rectangle

      Transparent rectangle

      Custom color fill rectangle

      Custom graphic fill rectangle

      Four 、 Implement a brush

      5、 ... and 、 Draw fan

      6、 ... and 、 Drawing ellipse

      7、 ... and 、 A circle

      8、 ... and 、 The output text

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One 、 Draw a straight line

    Drawing a straight line requires a starting point and an ending point , When the mouse is pressed, it is recorded as the starting point coordinate , When the mouse pops up, it is recorded as the end coordinate .

   First, add the left mouse button press event in the class wizard , And the left mouse button pop-up event

  Add a through the class wizard CPoint The member variable of type is used to record the position when the left mouse button is pressed

    Supplementary event code

void CMFCApplication6View::OnLButtonDown(UINT nFlags, CPoint point)
{	
	m_pOrigin = point;
	CView::OnLButtonDown(nFlags, point);
}

void CMFCApplication6View::OnLButtonUp(UINT nFlags, CPoint point)
{
    // Get device context 
    CDC* pDC = GetDC();
    // Move to the starting position 
	pDC->MoveTo(m_pOrigin);
    // Draw a straight line from the place to the end 
	pDC->LineTo(point);
	 Release the device context 
	ReleaseDC(pDC);
	CView::OnLButtonUp(nFlags, point);
}

Change the brush style

    stay MFC Through CPen Redefine a brush style

CPen pen( Pen shape , Line width , Color )

• Pen shape ：PS_SOLID Solid line , PS_DASH Dotted line , PS_DOT Dotted line , PS_DOTDASH Point line
• Line width ： Pixel for unit
• Color ：RGB(RED,GREE,BLUR)

    For example, I want to change the straight line drawn above to 5 Pixel width , green

    At this time, you need to customize a brush , Replace the default brush of the device context . But be careful ： When you stop using the custom brush, you need to replace the default brush of the device context

void CMFCApplication6View::OnLButtonDown(UINT nFlags, CPoint point)
{
	m_pOrigin = point;
	CView::OnLButtonDown(nFlags, point);
}


void CMFCApplication6View::OnLButtonUp(UINT nFlags, CPoint point)
{
	// Get device context 
	CDC* pDC = GetDC();
	 Define the brush 
	CPen pen(PS_SOLID, 5, RGB(0,255, 0));
	// Replace the device context default brush , And keep the original brush 
	CPen* pOldPen = pDC->SelectObject(&pen);
	pDC->MoveTo(m_pOrigin);
	pDC->LineTo(point);
	// The device context reverts to the original brush 
	pDC->SelectObject(pOldPen);
	 Release the device context 
	ReleaseDC(pDC);
	CView::OnLButtonUp(nFlags, point);
}

Two 、 Use the brush to draw a rectangle

When drawing a rectangle with a brush , You need the coordinates of the upper left corner and the lower right corner of the rectangle , When the mouse is pressed, it is recorded as the coordinates of the upper left corner , When the mouse pops up, it is recorded as the coordinates of the lower right corner .

void CMFCApplication6View::OnLButtonDown(UINT nFlags, CPoint point)
{
	m_pOrigin = point;
	CView::OnLButtonDown(nFlags, point);
}

void CMFCApplication6View::OnLButtonUp(UINT nFlags, CPoint point)
{
	// A brush 
	// Get device context , Compared with the above method, this method obtains the device context dc It's a local variable , Automatically release after the program ends , Manually release the device context out of order 
	CClientDC dc(this);
	// Opaque brush 
	dc.Rectangle(CRect(m_pOrigin,point));

	CView::OnLButtonUp(nFlags, point);
}

Transparent rectangle

    If you want to draw a transparent rectangle , Get the transparent brush defined by the system , Replace the default brush of the device context , When the transparent brush is not used, you need to replace the original brush

void CMFCApplication6View::OnLButtonDown(UINT nFlags, CPoint point)
{
	m_pOrigin = point;
	CView::OnLButtonDown(nFlags, point);
}

void CMFCApplication6View::OnLButtonUp(UINT nFlags, CPoint point)
{
	// A brush 
	// Get device context 
	CClientDC dc(this);
	// Transparent brush 
	// Get the system transparent brush 
	CBrush* brush = CBrush::FromHandle((HBRUSH)GetStockObject(NULL_BRUSH));
	// Change the device context brush 
	CBrush* oldBrush = dc.SelectObject(brush);
	dc.Rectangle(CRect(m_pOrigin, point));
	// Change the device context back to the original brush 
	dc.SelectObject(oldBrush);

	CView::OnLButtonUp(nFlags, point);
}

Custom color fill rectangle

Want to customize the filling of the rectangle , Just pass in the custom brush color fill as a parameter when drawing the fill rectangle

void CMFCApplication6View::OnLButtonDown(UINT nFlags, CPoint point)
{
	m_pOrigin = point;
	CView::OnLButtonDown(nFlags, point);
}

void CMFCApplication6View::OnLButtonUp(UINT nFlags, CPoint point)
{
	// A brush 
	// Get device context 
	CClientDC dc(this);
	// Rectangle painted with fill color 
	CBrush brush(RGB(255, 0, 0));
	dc.FillRect(CRect(m_pOrigin, point), &brush);

	CView::OnLButtonUp(nFlags, point);
}

Custom graphic fill rectangle

    To draw a custom graphic fill, you first need to add a graphic you want to fill in the resource view , Here we use built-in resources Bitmap Draw a picture you want to fill .

First step ： add to Bitmap resources

Right click “ project ”, choice “ add to ”, add to “ resources ”

choice Bitmap, Choose new

The second step ： Draw custom graphics

After the “ Resource view ” You can view the added resources in

The third step ： Load the drawn picture

Make a statement Bitmap, Load the picture just drawn from the resource view , Declared Bitmap Object as parameter , Declare a brush object

void CMFCApplication6View::OnLButtonDown(UINT nFlags, CPoint point)
{
	m_pOrigin = point;

}

void CMFCApplication6View::OnLButtonUp(UINT nFlags, CPoint point)
{
	// A brush 
	// Get device context 
	CClientDC dc(this);

	CBitmap bitmap;
	// Load pictures from resources into bitmap in 
	bitmap.LoadBitmap(IDB_BITMAP1);
	// With bitmap Is the parameter , Generate brush objects 
	CBrush brush(&bitmap);
	// Fill the rectangular area 
	dc.FillRect(CRect(m_pOrigin, point), &brush);

	CView::OnLButtonUp(nFlags, point);
}

Four 、 Implement a brush

Pressing the left mouse button will start drawing as the mouse moves , Stop drawing when the left button pops up

    Add a mouse movement event “OnMouseMove”, And a member parameter “m_bDraw（bool）” Record whether the left mouse button is pressed . When the mouse moves, first judge m_bDraw, If m_bDraw by true Then press the left key , Began to draw , Otherwise stop drawing

void CMFCApplication6View::OnLButtonDown(UINT nFlags, CPoint point)
{
	m_pOrigin = point;
    m_bDraw = TRUE;
	CView::OnLButtonDown(nFlags, point);
}


void CMFCApplication6View::OnLButtonUp(UINT nFlags, CPoint point)
{

	// Press the key up to set false
	m_bDraw = false;
	CView::OnLButtonUp(nFlags, point);
}


void CMFCApplication6View::OnMouseMove(UINT nFlags, CPoint point)
{
	CClientDC dc(this);
    // Draw a line after clicking the mouse 
	if (m_bDraw) {
		dc.MoveTo(m_pOrigin);
		dc.LineTo(point);
		m_pOrigin = point;
	}
	CView::OnMouseMove(nFlags, point);
}

5、 ... and 、 Draw fan

The sector only needs to start every time when the left mouse button is pressed before the left mouse button pops up

void CMFCApplication6View::OnLButtonDown(UINT nFlags, CPoint point)
{
	m_pOrigin = point;
    m_bDraw = TRUE;
	CView::OnLButtonDown(nFlags, point);
}


void CMFCApplication6View::OnLButtonUp(UINT nFlags, CPoint point)
{

	// Press the key up to set false
	m_bDraw = false;
	CView::OnLButtonUp(nFlags, point);
}


void CMFCApplication6View::OnMouseMove(UINT nFlags, CPoint point)
{
	CClientDC dc(this);
	CPen pen(PS_DOT, 1, RGB(0, 255, 255));
	// Draw fan 
	CPen* oldPen = dc.SelectObject(&pen);
	if (m_bDraw) {	
		dc.MoveTo(m_pOrigin);
		dc.LineTo(point);
	}
	dc.SelectObject(oldPen);
	CView::OnMouseMove(nFlags, point);
}

6、 ... and 、 Drawing ellipse

    Ellipse drawing mechanism is based on rectangle , Just call the draw ellipse function .

void CMFCApplication6View::OnLButtonDown(UINT nFlags, CPoint point)
{
	m_pOrigin = point;
	CView::OnLButtonDown(nFlags, point);
}


void CMFCApplication6View::OnLButtonUp(UINT nFlags, CPoint point)
{

	CClientDC dc(this);
	CPen pen(PS_SOLID, 5, RGB(0, 0, 255));
	CPen* oldpen = dc.SelectObject(&pen);
	// Drawing ellipse 
	dc.Ellipse(CRect(m_pOrigin, point));

	CView::OnLButtonUp(nFlags, point);
}

7、 ... and 、 A circle

void CMFCApplication6View::OnLButtonDown(UINT nFlags, CPoint point)
{
	m_pOrigin = point;
	CView::OnLButtonDown(nFlags, point);
}


void CMFCApplication6View::OnLButtonUp(UINT nFlags, CPoint point)
{
	m_bDraw = false;
	CClientDC dc(this);
	CPen pen(PS_SOLID, 5, RGB(0, 0, 255));
	CPen* oldpen = dc.SelectObject(&pen);
	// A circle 
	long len = point.x - m_pOrigin.x;
	dc.Ellipse(m_pOrigin.x, m_pOrigin.y, m_pOrigin.x + len, m_pOrigin.y + len);


	CView::OnLButtonUp(nFlags, point);
}

8、 ... and 、 The output text

void CMFCApplication6View::OnLButtonUp(UINT nFlags, CPoint point)
{
	m_bDraw = false;
	CClientDC dc(this);
	CString str(" Here comes Xiao Ming ");
	// Set the text color 
	dc.SetTextColor(RGB(0, 255, 0));
	// Set text font 
	CFont font;

	// Create dot matrix fonts 
	// How many dot fonts are passed , Pass in 200, The font is 20
	font.CreatePointFont(200, " Chinese Xingkai ");
	// Output string 
	dc.TextOut(point.x, point.y, str, str.GetLength());
	CView::OnLButtonUp(nFlags, point);
}