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Overview
This sample, from Cayce Cochran (cayce@fastlane.net), demonstrates
how to use a dialog template with a File Open or Save CommonDialog. It takes advantage of the
CommonDialog/Direct DLL component which now (versions dated 1 November 1999 and
higher) includes the relevant support for templates.
About Dialog Templates
A dialog template is a concept popular in C and C++ coding. Basically it works like a really rubbish
version of VB: you lay out the components of the resource in some sort of WYSIWYG environment, which is
then written to a resource. When you come to show the dialog box in the C program, you pass in the
dialog template resource and the appropriate functions are invoked to create the specified controls
on your dialog for you.
Templates can be created quite easily if you have a Resource Editor tool (such as the ones provided
with VC++, which will even import a VB form for you and spit out the equivalent dialog template). If
you're feeling particularly in the mood for this sort of functionality then you should see it isn't
particularly difficult to create your own by hand. Look at the files WAdlgres.rc and
Resource.h in the download for hints on the format of a template.
Resources And VB
The first problem is the fact that the Common Dialog template function requires the template to
be included in a resource in the executable. However, resources in VB apps are hidden from the
API functions whilst you are debugging the app in IDE (you can only read VB resources in the IDE
using the standard VB resource functions LoadResPicture, LoadResData and
LoadResString).
Anyway, this problem is easy to work around by compiling the resource into a DLL and then using
that when working in the IDE. The easiest way to do this is to
create a VB ActiveX DLL project, add the .RES file to it and compile that (you may want to add a dummy
method to the default Class1 just to give VB something to do when creating it).
Determining whether you are in the IDE or not is achieved using the classic Debug.Assert check:
Private m_bInIDE As Boolean
Public Property Get InIDE() As Boolean
Debug.Assert (IsInIDE)
InIDE = m_bInIDE
End Property
Private Property Get IsInIDE() As Boolean
m_bInIDE = True
IsInIDE = True
End Property
Because Debug.Assert code is only run when you are in the IDE, when the code is compiled the
IsInIDE property is never called, and therefore the m_bInIDE property is never set to
True.
CommonDialog/Direct and Dialog Templates
Telling the CommonDialog/Direct library to use a dialog template when it is shown
is achieved by setting two properties:
- The TemplateName property (which accepts a the resource ID as a Long value).
- A parameter indicating where the resource can be found. If you are running in compiled code with
the resource compiled into the executable, then set the hInstance property to the
App.hInstance value.
Otherwise, use cdLoadLibrary to specify to CommonDialog/Direct
the filename of a DLL or EXE including the dialog as a resource. You must remember to call
cdFreeLibrary to free up the resources associated with loading the file.
Because you probably need to know the value of any additional controls in your template, you should
set the CommonDialog/Direct HookDialog flag to True. Having done this the class will
raise InitDialog and WMCommand events, which you can use to populate controls and
respond to changes in their values.
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Download the Common Dialog Template Sample (43kb)