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| 32 | <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 QMotifDialog</h1>
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| 33 |
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| 34 |
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| 35 |
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| 36 | [ <a href="motif-walkthrough-4.html">Previous: Using Custom QDialogs</a> ]
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| 37 | [ <a href="motif-walkthrough.html">Home</a> ]
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| 38 | [ <a href="motif-walkthrough-6.html">Next: Using Qt Main Window Classes</a> ]
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| 39 | <p> As mentioned earlier, the <em>Print</em> dialog cannot be replaced until we
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| 40 | have converted the <em>View</em> widget. The <em>Print</em> dialog will be
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| 41 | removed once we have finished our migration, since we will use
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| 42 | <a href="qprinter.html">QPrinter</a> instead. Based on this information, we decide that it is not
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| 43 | worth replacing the <em>Print</em> dialog with a custom <a href="qdialog.html">QDialog</a> replacement.
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| 44 | Instead, we will keep the <a href="motif-extension.html#Motif">Motif</a> based dialog and use <a href="qmotifdialog.html">QMotifDialog</a> to
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| 45 | integrate the dialog with the application.
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| 46 | <p> <h2> Modality Requirements
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| 47 | </h2>
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| 48 | <a name="1"></a><p> Modality with QDialog is different from Motif. The <a href="qdialog.html#exec">QDialog::exec</a>()
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| 49 | function does not return until the dialog is finished. In Motif,
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| 50 | modality is simply a property of the shell, and the application
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| 51 | programmer must write QDialog::exec() style functionality if they
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| 52 | want that behavior.
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| 53 | <p> Since we will be using QMotifDialog (which is a QDialog subclass), we
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| 54 | will need to have an <em>accept</em> and a <em>reject</em> callback for each
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| 55 | dialog we integrate with QMotifDialog. The predefined Motif dialogs
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| 56 | have these already: the <tt>XmNokCallback</tt> and <tt>XmNcancelCallback</tt>
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| 57 | callbacks. However, the <em>Print</em> dialog only has an <em>accept</em> callback
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| 58 | (the <tt>XmdNprintCallback</tt>), but it does not have a <em>reject</em> callback.
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| 59 | We need to add this.
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| 60 | <p> This is easily done. We add an <tt>XtCallbackList</tt> for the <tt>XmNcancelCallback</tt> callback in <tt>Xmd/PrintP.h</tt>:
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| 61 | <p>
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| 62 |
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| 63 | <pre></pre>
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| 64 | <p> We add the <tt>XmNcancelCallback</tt> callback to the list of resources for
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| 65 | the <tt>XmdPrint</tt> widget class in <tt>Xmd/Print.c</tt>:
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| 66 | <p>
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| 67 |
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| 68 | <pre></pre>
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| 69 | <p> We need to activate this callback whenever we unmanage the widget and
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| 70 | do not activate the <em>print</em> callback, which is in the <tt>do_help_cb()</tt>
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| 71 | function:
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| 72 | <p> <pre></pre>
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| 73 | <p> ... and in the unmanage_cb() function:
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| 74 | <p> <pre></pre>
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| 75 | <p> <h2> Integrating the <em>Print</em> Dialog
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| 76 | </h2>
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| 77 | <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="qmotifdialog.html">QMotifDialog</a>. First we need to include
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| 78 | the QMotifDialog header in <tt>todo.cpp</tt>.
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| 79 | <p>
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| 80 |
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| 81 | <p> <pre></pre>
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| 82 | <p> We add a <tt>ShowPrintDialog()</tt> function which will create and execute the
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| 83 | print dialog.
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| 84 | <p> <pre></pre>
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| 85 | <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="qmotifwidget.html">QMotifWidget</a>, which
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| 86 | we will use as the parent for the dialog.
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| 87 | <p> <pre></pre>
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| 88 | <p> The <tt>ShowPrintDialog()</tt> function creates the <em>Print</em> dialog and
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| 89 | executes it. We use the <tt>XmdNprintCallback</tt> callback to accept the
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| 90 | dialog and the <tt>XmNcancelCallback</tt> callback to reject the dialog. We
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| 91 | can do this easily by using the <a href="qmotifdialog.html#acceptCallback">QMotifDialog::acceptCallback</a>() and
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| 92 | <a href="qmotifdialog.html#rejectCallback">QMotifDialog::rejectCallback</a>() functions, respectively. We also
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| 93 | ensure that the <em>print</em> callback continues to call the <tt>Print()</tt> function as before.
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| 94 | <p> <pre></pre>
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| 95 | <p> After we build the project, the application runs and operates as
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| 96 | expected. There is no visual or behavioral difference, even though
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| 97 | the <em>Print</em> dialog is using <a href="qmotifdialog.html">QMotifDialog</a>.
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| 98 | <p> [ <a href="motif-walkthrough-4.html">Previous: Using Custom QDialogs</a> ]
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| 99 | [ <a href="motif-walkthrough.html">Home</a> ]
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| 100 | [ <a href="motif-walkthrough-6.html">Next: Using Qt Main Window Classes</a> ]
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| 101 | <p>
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