Advanced MFC Programming

Chapter 13. Adding Special Features to Application
……
pDocTemplate = new CMultiDocTemplate(
IDR_PIETYPE,
RUNTIME_CLASS(CChartDoc),
RUNTIME_CLASS(CChildFrame),
RUNTIME_CLASS(CPieView));
AddDocTemplate(pDocTemplate);
With the above implementation, when a new client is about to be created, the user will be prompted to
choose from one of the two types of views. Here strings that are included in the prompt dialog box should
be prepared as sub-strings contained in the string resources that are used to identify document type
(IDR_CHARTTYPE and IDR_PIETYPE in the sample).
The format of the document type string is the same with that of a normal MDI application, which
comprises several sub-strings. The most important ones are the first two sub-strings: one will be used as the
default title of the client window and the other will be used in the prompt dialog box to let the user select an
appropriate view when a new client window is about to be created. In the sample, the contents of string
IDR_CHARTYPE and IDR_PIETYPE are as follows:
\nBar\nBar\n\n\nChart.Document\nChart Document
\nPie\nPie\n\n\nChart.Document\nChart Document
Both the window and the string contained in the prompt dialog box for chart view are set to “Bar”, for
pie view, they are set to “Pie”.
Window Origin and View Port Origin
When implementing drawing on the target device, sometimes it is more convenient if we use
appropriate coordinate system. As a programmer, when we write code to draw geometrical shapes, we are
always working on Page-Space (logical space). The actual output would happen on Device-Space. By
default, one logical unit is mapped to one device unit, and both origins are located at upper-left corners.
When drawing certain types of geometrical shapes, for example, a circle, it would be more convenient
if we adjust the origin of the coordinate system so that it is located at the center of the circle (See Figure
13-3).
Describing this circle
is difficult, because its
coordinates are not
symmetric
Figure 13-3. Two types of coordinate systems
To offset origin in either page-space or device-space, we can use the following functions:
Function Name
CDC::SetWindowOrg(…)
CDC::OffsetWindowOrg(…)
CDC::SetViewportOrg(…)
CDC::OffsetViewportOrg(…)
Usage
Set origin to a specific position in page-space
Offset origin to a new position in page-space
Set origin to a specific position in device-space
Offset origin to a new position in device-space
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