Visual C++ and MFC Programming 2nd Edition

Chapter 9 Strings Visual C++ and MFC Fundamentals

You should not rely on the above picture. After calling the CDC::SetMapMode() function

with MM_ISOTROPIC (or MM_ANISOTROPIC) as argument, you are not supposed to

stop there. The purpose of these two map modes is to let you control the orientation of the

axes and the conversion of the units.

The difference between both mapping modes is that, when using the MM_ISOTROPIC

map mode, one unit in the horizontal axis is equivalent to one unit in the vertical axis.

This is not the case for the MM_ANISOTROPIC map mode which allows you to control

however the units should be converted on each individual axis.

Therefore, after calling SetMapMode() and specifying the MM_ISOTROPIC (or

MM_ANISOTROPIC), you must call the CDC:SetWindowExt() member function. This

method specifies how much each new unit will be multiplied by the old or default unit

system. The CDC::SetWindowExtEx() member function comes in two versions with the

following syntaxes:

CSize SetWindowExt(int cx, int cy);

CSize SetWindowExt(SIZE size);

If using the first version, the first argument to this function, cx, specifies the logical

conversion multiplier used for each unit on the horizontal axis. The second argument, cy,

specifies the logical conversion multiplier used for each unit on the vertical axis.

The second version of the method can be used if you know the desired logical width and

height as a SIZE structure. Here is an example:

void CExoView::OnDraw(CDC* pDC)

{

CExoDoc* pDoc = GetDocument();

ASSERT_VALID(pDoc);

CPen PenRed(PS_SOLID, 1, RGB(255, 0, 0));

CBrush BrushAqua(RGB(0, 255, 255));

CBrush *brOld;

CPen *pnOld;

pnOld = pDC->SelectObject(&PenRed);

brOld = pDC->SelectObject(&BrushAqua);