Advanced MFC Programming

Chapter 1. Tool Bar and Dialog Bar
When we create tool bar resource, the control IDs are generated contiguously according to the
sequence of creation. For example, if we first create the blue button, then the green button, the two IDs will
have the following relationship:
ID_BUTTON_GREEN = ID_BUTTON_BLUE+1
Modifying an ID
Sometimes we don’t know if the IDs of the tool bar buttons have contiguous values, because most of
the time we use only symbolic IDs and seldom care about the actual values of them. If the IDs do not meet
our requirement and we still want to use the above message mapping macros, we need to modify the ID
values by ourselves.
By default, all the resource IDs are defined in file “resource.h”. Although we could open it with a text
editor and make changes, there is a better way to do so. First, an ID value could be viewed in the Developer
Studio by executing View | Resource symbols… command. This command will bring up a dialog box that
contains all the resource IDs used by the application (Figure 1-3).
If we want to make change to any ID value, first we need to highlight that ID, then click the button
labeled “Change…”. After that, a “Change Symbol” dialog box will pop up, if the ID is used for more than
one purpose, we need to select the resource type in “Used by” window (This happens when this ID is used
for both command ID and string ID, in which case the string ID may be used to implement flyby and tool
tip. See Figure 1.9). In our sample, there is only one type of resource that uses the button IDs, so we do not
need to make any choice. Now click “View Use” button (Figure 1-4), which will bring up “Toolbar Button
Properties” property sheet. Within “General” page, we can change the ID’s value by typing in a new
number in the window labeled “ID”. For example, if we want to change the value of ID_BUTTON_RED to
32770, we just need to type in an equal sign and a number after the symbolic ID so that this edit window
has the following contents (Figure 1-5):
ID_BUTTON_RED=32770
Resource ID
ID value
Figure 1-3. View resource IDs and their values
With this method, we can easily change the values of four resource IDs (ID_BUTTON_RED,
ID_BUTTON_GREEN, ID_BUTTON_BLUE, ID_BUTTON_YELLOW) and make them contiguous. After this we can
map all of them to a single member function instead of implementing message handlers for each ID.
Unfortunately, Class Wizard doesn’t do range mappings, so we have to implement it by ourselves.
Sample 1.4\Bar demonstrates how to implement this kind of mapping. It is based upon sample 1.2\Bar,
which already contains the default message mapping macros:
BEGIN_MESSAGE_MAP(CBarDoc, CDocument)
//{{AFX_MSG_MAP(CBarDoc)
ON_COMMAND(ID_BUTTON_BLUE, OnButtonBlue)
ON_COMMAND(ID_BUTTON_GREEN, OnButtonGreen)
ON_COMMAND(ID_BUTTON_RED, OnButtonRed)
ON_COMMAND(ID_BUTTON_YELLOW, OnButtonYellow)
ON_UPDATE_COMMAND_UI(ID_BUTTON_BLUE, OnUpdateButtonBlue)
ON_UPDATE_COMMAND_UI(ID_BUTTON_GREEN, OnUpdateButtonGreen)
ON_UPDATE_COMMAND_UI(ID_BUTTON_RED, OnUpdateButtonRed)
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