asked on

Drawing to the screen

I am in a dialog box. the m_Picture is a Picture control (static).

CDC *testdc;
testdc = m_Picture.GetWindowDC();
testdc->SetMapMode(MM_HIENGLISH);
CPen pen5;
pen5.CreatePen(PS_SOLID, 1, RGB(255,0,0));
testdc->SelectObject(&pen5);
testdc->Rectangle(0,0,500,500);
CPen pen6;
pen6.CreatePen(PS_SOLID, 1, RGB(255,0,0));
testdc->SelectObject(&pen6);
CRect rec;
m_Picture.GetClientRect(&rec);
testdc->DPtoLP(&rec);
//tried w/ & w/out
testdc->MoveTo(rec.top, rec.left);
testdc->LineTo(rec.bottom, rec.right);

Nothing comes out. Am I doing something wrong.

nietod

The problem is the mapping mode. In MM_HIENGLISH mode the Y value increases in the upward direction. Bot the origin will be the upper-left corner of the window so the window lies in the negative Y portion of the XY plane. But you are specifying coordinates that are positive Y, i.e. above the window.

jaiken

ASKER

I did change the MoveTo and LineTo (because I had the x/y backwards) but looking at rec upon return from GetClientRect and DPtoLP the y.bottom is a negative value. I get (0,0) and (2056, -2555). NOTE: I also got rid of the drawing of the rectangle to be more simple.

CDC *testdc;
testdc = m_Picture.GetWindowDC();
testdc->SetMapMode(MM_HIENGLISH);
CPen pen6;
pen6.CreatePen(PS_SOLID, 1, RGB(255,0,0));
testdc->SelectObject(&pen6);
CRect rec;
m_Picture.GetClientRect(&rec);
testdc->DPtoLP(&rec);
testdc->MoveTo(rec.left, rec.top);
testdc->LineTo(rec.right, rec.bottom);

nietod

Why do you use GetWindowDc() instead of GetDC?

Is the window open and visible?

ASKER CERTIFIED SOLUTION

fmharr

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nietod

I already pointed out that he should PROBABLY be using GetDC(). I don't think there is any evidence that the code is in InitDialog().

nietod

What was the problem?

jaiken

ASKER

I didn't have the code in the right place (OnDraw) function.