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< td align = "right" valign = "center" > < img src = "logo32.png" align = "right" width = "64" height = "32" border = "0" > < / td > < / tr > < / table > < h1 align = center > Using Existing Dialogs with TQMotifDialog< / h1 >
[ < a href = "motif-walkthrough-4.html" > Previous: Using Custom TQDialogs< / a > ]
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[ < a href = "motif-walkthrough-6.html" > Next: Using TQt Main Window Classes< / a > ]
< p > As mentioned earlier, the < em > Print< / em > dialog cannot be replaced until we
have converted the < em > View< / em > widget. The < em > Print< / em > dialog will be
removed once we have finished our migration, since we will use
< a href = "tqprinter.html" > TQPrinter< / a > instead. Based on this information, we decide that it is not
worth replacing the < em > Print< / em > dialog with a custom < a href = "tqdialog.html" > TQDialog< / a > replacement.
Instead, we will keep the < a href = "motif-extension.html#Motif" > Motif< / a > based dialog and use < a href = "tqmotifdialog.html" > TQMotifDialog< / a > to
integrate the dialog with the application.
< p > < h2 > Modality Requirements
< / h2 >
< a name = "1" > < / a > < p > Modality with TQDialog is different from Motif. The < a href = "tqdialog.html#exec" > TQDialog::exec< / a > ()
function does not return until the dialog is finished. In Motif,
modality is simply a property of the shell, and the application
programmer must write TQDialog::exec() style functionality if they
want that behavior.
< p > Since we will be using TQMotifDialog (which is a TQDialog subclass), we
will need to have an < em > accept< / em > and a < em > reject< / em > callback for each
dialog we integrate with TQMotifDialog. The predefined Motif dialogs
have these already: the < tt > XmNokCallback< / tt > and < tt > XmNcancelCallback< / tt >
callbacks. However, the < em > Print< / em > dialog only has an < em > accept< / em > callback
(the < tt > XmdNprintCallback< / tt > ), but it does not have a < em > reject< / em > callback.
We need to add this.
< p > This is easily done. We add an < tt > XtCallbackList< / tt > for the < tt > XmNcancelCallback< / tt > callback in < tt > Xmd/PrintP.h< / tt > :
< p >
< pre > < / pre >
< p > We add the < tt > XmNcancelCallback< / tt > callback to the list of resources for
the < tt > XmdPrint< / tt > widget class in < tt > Xmd/Print.c< / tt > :
< p >
< pre > < / pre >
< p > We need to activate this callback whenever we unmanage the widget and
do not activate the < em > print< / em > callback, which is in the < tt > do_help_cb()< / tt >
function:
< p > < pre > < / pre >
< p > ... and in the unmanage_cb() function:
< p > < pre > < / pre >
< p > < h2 > Integrating the < em > Print< / em > Dialog
< / h2 >
< a name = "2" > < / a > < p > Now that the < em > Print< / em > dialog has the appropriate < em > accept< / em > and < em > reject< / em > callbacks, we can use < a href = "tqmotifdialog.html" > TQMotifDialog< / a > . First we need to include
the TQMotifDialog header in < tt > todo.cpp< / tt > .
< p >
< p > < pre > < / pre >
< p > We add a < tt > ShowPrintDialog()< / tt > function which will create and execute the
print dialog.
< p > < pre > < / pre >
< p > We change the < em > Print< / em > menu item callback to call the new < tt > ShowPrintDialog()< / tt > function. We pass the top-level < a href = "tqmotifwidget.html" > TQMotifWidget< / a > , which
we will use as the parent for the dialog.
< p > < pre > < / pre >
< p > The < tt > ShowPrintDialog()< / tt > function creates the < em > Print< / em > dialog and
executes it. We use the < tt > XmdNprintCallback< / tt > callback to accept the
dialog and the < tt > XmNcancelCallback< / tt > callback to reject the dialog. We
can do this easily by using the < a href = "tqmotifdialog.html#acceptCallback" > TQMotifDialog::acceptCallback< / a > () and
< a href = "tqmotifdialog.html#rejectCallback" > TQMotifDialog::rejectCallback< / a > () functions, respectively. We also
ensure that the < em > print< / em > callback continues to call the < tt > Print()< / tt > function as before.
< p > < pre > < / pre >
< p > After we build the project, the application runs and operates as
expected. There is no visual or behavioral difference, even though
the < em > Print< / em > dialog is using < a href = "tqmotifdialog.html" > TQMotifDialog< / a > .
< p > [ < a href = "motif-walkthrough-4.html" > Previous: Using Custom TQDialogs< / a > ]
[ < a href = "motif-walkthrough.html" > Home< / a > ]
[ < a href = "motif-walkthrough-6.html" > Next: Using TQt Main Window Classes< / a > ]
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