Have you ever wanted the CCombobox class to display "readable" text when it is disabled? No matter whether it is a drop-down or a drop-list type of combobox!
Here's a class that'll do that (and much more, although the rest is not visually related)!
For example, in the pictures below, you can see the "before" and "after" effects of disabling the comboboxes using the standard "EnableWindow()" function call to either enable/disable the combobox.
The TComboBox class also provides mechanisms for quite a few time saving headaches when working with comboboxes, such as:
- Function calls to add entries into the combobox with "hidden" string information (i.e. in the screens above, the data "Item Data 1,2" is associated with the first combobox but is not visable). I know that Microsoft provides the "SetItemData()" member function for comboboxes, but it only allows for a DWORD, not a string. Therefore, there is no need to have global variables defined to contain the "hidden" information. Such an example is trying to use a CStringArray as data to be associated with the various entries in the combobox. As soon as the CStringArray goes out of scope, specifically if it is defined locally to a function, the data for the combobox will no longer be valid once the function exists.
- The ability to select an item based on the "hidden" code (i.e. in the above example, the statement to select the item in the third combobox was basically 'm_cbcDropDownNew.SelectCode(-1, "Item Data 1,2")'.
- The ability to "force fill" the combobox if the information isn't found. It is displayed differently (i.e. with special characters before/after the entry), to let you know that the entry was forced (the characters displayed are by default '+' and ';' - so a forced item would look like "+Drop List 3;").
- Let the combobox deal with duplicates (whether you want duplicates, or you don't).
- Function calls to switch the mode from drop-down to drop-list (so that you don't have to remember the style code necessary to switch to either).
Once you get the code, it is simple enough to add to whatever project you are working on, by opening up ClassWizard, and clicking on the "Add Class..." button in the upper right hand corner of ClassWizard. Click on "New..." from the drop down menu. The class name should be entered as CTComboBox, and the base class should be CCombobox. After clicking on OK, the files "TComboBox.h" and "TComboBox.cpp" will be generated. Once that is done, simply replace the files with the two that come with the demo project. I'd like to give you an easier way to do this, but I'm using VC 5.0, and haven't been able to find out any other way to add a class to a project (P.S. if anyone knows a better way, feel free to recommend one!).
Once you've added the class to the project, all you have to do to add member variables that are based on the "CTComboBox" class, is to "Add variable...", give the variable a name, set the "Category" to control, and a select "variable type" of "CTComboBox". ClassWizard will of course remind you that you need to include the "tcombobox.h" file in the header of the dialog itself.
DownloadsDownload demo project - 27 Kb
Download source - 8 Kb