五、实例代码
为了灵活使用逻辑坐标系，下面给出了几个例子代码：
例1：绘制带箭头的坐标轴
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void CExoDraw1View::OnPaint()
{
CPaintDC dc(this); // device context for painting
CBrush bgBrush(BLACK_BRUSH);
dc.SelectObject(bgBrush);
dc.Rectangle(Recto);
dc.SetMapMode(MM_ISOTROPIC);
dc.SetViewportOrg(0, 440);
dc.SetWindowExt(480, 480);
dc.SetViewportExt(440, -680);
CPen PenWhite(PS_SOLID, 1, RGB(255, 255, 255));
dc.SelectObject(PenWhite);
dc.MoveTo(21, 20);
dc.LineTo(21, 75);
// Up arrow
dc.MoveTo(16, 75);
dc.LineTo(21, 90);
dc.LineTo(26, 75);
dc.LineTo(16, 75);
dc.MoveTo(21, 22);
dc.LineTo(75, 22);
// Right arrow
dc.MoveTo(75, 17);
dc.LineTo(90, 22);
dc.LineTo(75, 27);
dc.LineTo(75, 17);
dc.SetBkMode(TRANSPARENT);
dc.SetTextColor(RGB(255, 255, 255));
dc.TextOut(16, 114, ’Y’);
dc.TextOut(100, 32, ’X’);
dc.Rectangle(15, 15, 30, 30);
}
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图二十二、代码效果图 |
例2：绘制网格
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void CExoDraw1View::OnPaint()
{
CPaintDC dc(this); // device context for painting
CRect Recto;
GetClientRect(&Recto);
CBrush bgBrush(BLACK_BRUSH);
dc.SelectObject(bgBrush);
dc.Rectangle(Recto);
CPen PenBlue(PS_SOLID, 1, RGB(0, 0, 255));
dc.SelectObject(PenBlue);
for(int x = 0; x < Recto.Width(); x += 20)
{
dc.MoveTo(x, 0);
dc.LineTo(x, Recto.Height());
}
for(int y = 0; y < Recto.Height(); y += 20)
{
dc.MoveTo(0, y);
dc.LineTo(Recto.Width(), y);
}
}
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 图二十三、代码效果图 |
例3：点状网格
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void CExoDraw1View::OnPaint()
{
CPaintDC dc(this); // device context for painting
CRect Recto;
GetClientRect(&Recto);
CBrush bgBrush(BLACK_BRUSH);
dc.SelectObject(bgBrush);
dc.Rectangle(Recto);
for(int x = 0; x < Recto.Width(); x += 20)
{
for(int y = 0; y < Recto.Height(); y += 20)
{
dc.SetPixel(x, y, RGB(255, 255, 255));
}
}
}
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图二十四、代码效果 |
例4：正弦图形
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void CExoView::OnPaint()
{
CPaintDC dc(this); // device context for painting
// TODO: Add your message handler code here
dc.SetMapMode(MM_ANISOTROPIC);
dc.SetViewportOrg(340, 220);
dc.SetWindowExt(1440, 1440);
dc.SetViewportExt(-1440, -220);
CPen PenBlue(PS_SOLID, 1, RGB(0, 0, 255));
dc.SelectObject(PenBlue);
// Axes
dc.MoveTo(-300, 0);
dc.LineTo( 300, 0);
dc.MoveTo( 0, -1400);
dc.LineTo( 0, 1400);
// I am exaggerating with the PI value here but why not?
const double PI = 3.141592653589793238462643383279;
// The following two values were chosen randomly by me.
// You can chose other values you like
const int MultiplyEachUnitOnX = 50;
const int MultiplyEachUnitOnY = 250;
for(double i = -280; i < 280; i += 0.01)
{
double j = sin(PI / MultiplyEachUnitOnX * i) * MultiplyEachUnitOnY;
dc.SetPixel(i, j, RGB(255, 0, 0));
}
// Do not call CView::OnPaint() for painting messages
}
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图二十五、代码效果图 |
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