MFC: Drawing base

Drawing 2.2 with GDI

2.2.1 drawing lines and curves

DC CPaintDC (the this); 
 
// draw a line, (0,0) for the top left corner of the screen 
dc.MoveTo (0,0); // starting point 
dc.LineTo (0,100); // end 
 
// a rectangle 
POINT aPoint [ . 5] = {0,0, 0,100, 100,100, 100,0, 0,0}; 
dc.Polyline (a aPoint,. 5); 
 
 
dc.MoveTo (0,0); 
the POINT a aPoint [. 4] = {0,100, 100,100, 100,0, 0,0}; 
dc.PolylineTo (a aPoint,. 4); 
 
// Videos arcuate 
CRect RECT (0,0,200,100); 
a CPoint Point1 (0,100); 
a CPoint Point2 (200,100); 
dc.Arc (RECT, Point1 , Point2); 
 
// draw a Bezier curve 
the POINT aPoint1 [. 4] = {120,100, 120,200, 250,150, 500,40}; 
dc.PolyBezier (aPoint1,4);
 

 

2.2.2 painted oval / polygon / shape other

// painted oval 
dc.Ellipse (0,0,100,100); 
 
CRect RECT (0,0,100,100); 
dc.Ellipse (RECT); 
 
// draw a rectangle 
dc.Rectangle (0,0,800,400);

 

2.2.3 GDI brush and CPen class

The default is one pixel wide pen solid black line, if you need to create a GDI pen must CDC :: SelectObject () which will be selected into the device context

PEN a CPen (the PS_SOLID,. 1, the RGB (255,0,0)); 
 
// pen style: the PS_SOLID PS_DASH PS_DOT PS_DASHDOT PS_DASHDOTDOT PS_NULL PS_INSIDEFRAME 
a CPen PEN; 
pen.CreatePen (the PS_SOLID,. 1, the RGB (255,0,0)); 
 
// RGB primary colors 
black (0,0,0) white (255,255,255) red (192,0,0) yellow (192,192,0) green (0,192,0) cyan (0,192,192) 
blue (0,0,192)

 

2.2.4 GDI brush and CBrush class

The default closed figure shown is filled with white pixels, by creating a GDI brush and it is selected into the device context, you can change the fill color pattern

CBrush brush(RGB(255,0,0));
 
CBrush brush;
brush.CreateSolidBrush(RGB(255,0,0));
 
//画刷样式:HS_BDIAGONAL HS_FDIAGONAL HS_CROSS HS_HORIZONTAL HS_DIAGCROSS HS_VERTICAL
CBrush brush(HS_DIAGCROSS,RGB(255,255,255));

 

2.2.5 text painting

// draw text in the middle of the screen 
CRect RECT; 
GetClientRect (& RECT); 
 
dc.DrawText (_T ( "the Hello, MFC"), - 1, & RECT, DT_SINGLELINE | DT_CENTER | DT_VCENTER); 
dc.TextOut (0, 0, CString ( _T ( "the Hello the MFC"))); 
 
// change the text attributes 
dc.SetTextAlign (TA_RIGHT); 
dc.SetTextColor () / dc.SetBkColor ()

 

2.2.6 GDI font type and CFont

CFont font;
font.CreatePointFont(120,_T("Times New Roman"));
 
CPaintDC dc(this);
dc.SelectObject(&font);

 

2.2.7 raster fonts and TrueType fonts

TrueType fonts can be scaled to any size: Times New Roman / Arial / Courier New / Symbol

 

2.2.8 rotated fonts

2.2.9 backup objects

There are some ready-made spare interior windows objects (such as the pen / brush / fonts, etc.), so do not create our own

 

2.2.10 delete GDI objects

And GDI objects associated CGdiObject by calling CGdiObject :: DeleteObject explicitly deleted

// source .cpp 
 
// add a first row 
#ifdef _DEBUG 
 
#define new new DEBUG_NEW 
 
#undef THIS_FILE 
 
static char THIS_FILE [] = __FILE__; 
 
#endif 
 
 
// added at the end of the function 
_CrtDumpMemoryLeaks (); 
 
// check VS debugging information, which will The first few lines of the file has a memory leak

 

2.2.11 deselecting GDI object

We want to delete GDI objects, it is best to select an object from the GDI DC environment inside, in order to avoid a crash, the best way is to use a spare to replace the object we need to remove the objects

// spare target audiences to replace 
a CPen PEN (the PS_SOLID,. 1, the RGB (255,0,0)); 
dc.SelectObject (& PEN); 
the CBrush Brush (the RGB (0,0,255)); 
dc.SelectObject (& Brush) ; 
... 
dc.SelectStockObject (BLACK_PEN); 
dc.SelectStockObject (WHITE_BRUSH); 
 
the Delete PEN; 
the Delete Brush;