This article shows by example how to implement scaling properly.
Printing an embedded object from an AppWizard-generated OLE container
application may cause the printout of the embedded object to appear
too small.
The developer of an OLE container must implement the code to scale an
embedded object properly from the screen device to the printer device. If
only the screen device is considered, the embedded object will appear too
small on a printout.
Sample code
/* Compile options needed: none
*/
In the MFC Container sample, step 2 implements a container that does not
consider the difference in resolution between the screen device and
the printer device. If, for instance, Scribble, step 7 is embedded in
Container and PRINT or PRINT PREVIEW is selected, the embedded object
will appear too small.
Using Container as an example of MFC container that doesn't support
scaling, the following code can be added to CContainView::OnDraw() to
implement proper scaling:
void CContainerView::OnDraw(CDC* pDC)
{
CContainerDoc* pDoc = GetDocument();
ASSERT_VALID(pDoc);
// draw the OLE items from the list
POSITION pos = pDoc->GetStartPosition();
while (pos != NULL)
{
// draw the item
CContainerItem* pItem = (CContainerItem*)pDoc->GetNextItem(pos);
// copy the client items rect, which will be scaled
CRect rect2(pItem->m_rect);
if(pDC->IsPrinting())
{
// get the printer's pixel resolution
int ixp=pDC->GetDeviceCaps(LOGPIXELSX);
int iyp=pDC->GetDeviceCaps(LOGPIXELSY);
// get the current window's resolution
CDC* pddc = GetDC();
int ixd=pddc->GetDeviceCaps(LOGPIXELSX);
int iyd=pddc->GetDeviceCaps(LOGPIXELSY);
// scale rect2 up by the ratio of the resolutions
int width = MulDiv(rect2.Width(),ixp, ixd);
int height = MulDiv(rect2.Height(), iyp, iyd);
rect2.left = MulDiv(rect2.left, ixp, ixd);
rect2.top = MulDiv(rect2.top, ixp, ixd);
rect2.right = rect2.left + width;
rect2.bottom = rect2.top + height;
}
pItem->Draw(pDC, rect2);
if(!pDC->IsPrinting())
{
// draw the tracker over the item
CRectTracker tracker;
SetupTracker(pItem, &tracker);
tracker.Draw(pDC);
}
}
}
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