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diff --git a/doc/html/motif-walkthrough-8.html b/doc/html/motif-walkthrough-8.html new file mode 100644 index 000000000..40bc1f1a3 --- /dev/null +++ b/doc/html/motif-walkthrough-8.html @@ -0,0 +1,212 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> +<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/extensions/motif/doc/walkthrough.doc:1190 --> +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> +<title>Replacing the View Widget</title> +<style type="text/css"><!-- +fn { margin-left: 1cm; text-indent: -1cm; } +a:link { color: #004faf; text-decoration: none } +a:visited { color: #672967; text-decoration: none } +body { background: #ffffff; color: black; } +--></style> +</head> +<body> + +<table border="0" cellpadding="0" cellspacing="0" width="100%"> +<tr bgcolor="#E5E5E5"> +<td valign=center> + <a href="index.html"> +<font color="#004faf">Home</font></a> + | <a href="classes.html"> +<font color="#004faf">All Classes</font></a> + | <a href="mainclasses.html"> +<font color="#004faf">Main Classes</font></a> + | <a href="annotated.html"> +<font color="#004faf">Annotated</font></a> + | <a href="groups.html"> +<font color="#004faf">Grouped Classes</font></a> + | <a href="functions.html"> +<font color="#004faf">Functions</font></a> +</td> +<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Replacing the View Widget</h1> + + + +[ <a href="motif-walkthrough-7.html">Previous: Refactoring Existing Code</a> ] +[ <a href="motif-walkthrough.html">Home</a> ] +[ <a href="motif-walkthrough-9.html">Next: Replacing the Print Dialog</a> ] +<p> We are ready to start replacing the <em>View</em> widget. However, our +example program uses the <tt>XmNotebook</tt> widget class. TQt does not +provide a direct equivalent of this class, so we are faced with three +possibilities, each with several advantages and disadvantages. +<p> <ol type=1> +<p> <li> We can continue the conversion using existing TQt widgets. +<p> <ul> +<p> <li> Advantages - The widgets provided by TQt are well designed and +tested, allowing us to tquickly redesign the user interface. +<p> <li> Disadvantages - Most, if not all, of the existing data structures +and code will need to be modified or rewritten. New code must be +written in a way that maintains compatibility with previous versions +of our application. +<p> </ul> +<p> <li> We can write a new <a href="qwidget.html">TQWidget</a> subclass that is identical to the <tt>XmNotebook</tt> widget class. +<p> <ul> +<p> <li> Advantages - The existing data structures will not change, allowing +compatibility with previous and future versions. +<p> <li> Disadvantages - The new widget will need to be written and +regression tested. Existing code in our application will need to be +changed in order to deal with the new widget's API. +<p> </ul> +<p> <li> We can leave the <tt>XmNotebook</tt> widget untouched. +<p> <ul> +<p> <li> Advantages - The existing data structures and code remain +unchanged, allowing us to continue development on other projects, +new features, etc. +<p> <li> Disadvantages - This is the simplest solution, but the application +will still be dependent upon X11; we will not be able to deploy our +application on all platforms supported by TQt. +<p> </ul> +<p> </ol> +<p> We will use the first approach to complete the migration of the +example project used in this walkthrough, using <a href="qtextedit.html">TQTextEdit</a>, <a href="qlabel.html">TQLabel</a> and +<a href="qspinbox.html">TQSpinBox</a> to provide a similar look. The only difference is that we +will not have tabs. +<p> We use <a href="designer-manual.html">TQt Designer</a> to add the +TQTextEdit, TQLabel and TQSpinBox widgets to the <em>Main Window</em> widget. +<p> <h2> Data Structure Modifications +</h2> +<a name="1"></a><p> The <tt>Page</tt> struct contains <tt>majorPB</tt> and <tt>minorPB</tt> members which +need to be removed. These members correspond to the tabs displayed in +the existing version. The new version will not have any tabs, so we +remove them. +<p> + +<pre></pre> +<p> <h2> Code Modifications +</h2> +<a name="2"></a><p> Most of the existing functions in our application need to be modified +to work with the new <em>View</em> widget. The <tt>MainWindow</tt> class has five +new functions that correspond to existing functions. +<p> <center><table cellpadding="4" cellspacing="2" border="0"> +<tr bgcolor="#a2c511"> <th valign="top">Existing Function <th valign="top">New Function +<tr bgcolor="#f0f0f0"> <td valign="top"><tt>void SetPage( int )</tt> <td valign="top"><tt>void MainWindow::setPage( int )</tt> +<tr bgcolor="#d0d0d0"> <td valign="top"><tt>void PageChange( ... )</tt> <td valign="top"><tt>void MainWnidow::pageChange( int )</tt> +<tr bgcolor="#f0f0f0"> <td valign="top"><tt>void TextChanged( ... )</tt> <td valign="top"><tt>void MainWnidow::textChanged()</tt> +<tr bgcolor="#d0d0d0"> <td valign="top"><tt>void ReadDB( char * )</tt> <td valign="top"><tt>void MainWindow::readDB( char * )</tt> +<tr bgcolor="#f0f0f0"> <td valign="top"><tt>void SaveDB( char * )</tt> <td valign="top"><tt>void MainWindow::saveDB( char * )</tt> +</table></center> +<p> <a name="mainwindow-ui-h-view-widget-modifications"></a> +<p> The <tt>SetPage()</tt> function implementation is moved to the <tt>MainWindow::setPage()</tt> function in <tt>mainwindow.ui.h</tt>. We remove the +<tt>SetPage()</tt> function declaration and implementation from <tt>page.h</tt> +and <tt>actions.cpp</tt>, respectively. In order to make <tt>MainWindow::setPage()</tt> work correctly, we need to modify the code to +use the new widgets in our <em>Main Window</em> widget. +<p> + +<pre></pre> +<p> First, we set the current value of the <tt>spinbox</tt> to the current page +number. +<p> <pre></pre> +<p> Next, we set the current text and cursor position of the <tt>textedit</tt> +to the contents of the current page. +<p> <pre></pre> +<p> If the current page has a custom label, we set it as the current text +of the <tt>textlabel</tt>; otherwise we set the <tt>textlabel</tt> contents to +"Page X" (where X is the current page number). +<p> <pre></pre> +<p> If the current page has major and/or minor tab text, we append these +to the <tt>labeltext</tt>. This ensures that all information entered by the +user remains visible. +<p> <pre></pre> +<p> We should continue to handle the possibility that the current page +does not exist. In this case, we clear the contents of the <tt>textedit</tt> widget and set the <tt>textlabel</tt> contents to the current page +number (with an indication that the page is invalid). +<p> <pre></pre> +<p> The <tt>PageChange()</tt> function is moved from <tt>todo.cpp</tt> to the <tt>MainWindow::pageChange()</tt> function in <tt>mainwindow.ui.h</tt>. As with the +<tt>MainWindow::setPae()</tt> function, we need to modify the code to use +the new widgets in our <em>Main Window</em> widget. +<p> Note: <a href="qtextedit.html#text">TQTextEdit::text</a>() returns a <a href="qstring.html">TQString</a>, which needs to be converted +into a normal <tt>char*</tt> array. To do this we create a copy of the +string in the local encoding. We need to make the copy using <a href="qcstring.html#qstrdup">qstrdup</a>() because the data contained in the <a href="qcstring.html">TQCString</a> returned by +<a href="qstring.html#local8Bit">TQString::local8Bit</a>() is deallocated when the TQCString is destroyed. +<p> <pre></pre> +<p> The <tt>TextChanged()</tt> function does nothing more than set the <tt>modified</tt> variable to 1. Our new <tt>MainWindow::textChanged()</tt> function +does exactly the same. +<p> <pre></pre> +<p> Since both the <tt>MainWindow::pageChange()</tt> and <tt>MainWindow::textChanged()</tt> functions access the <tt>modified</tt> global +variable, we add a forward declaration at the top of <tt>mainwindow.ui.h</tt>. +<p> <a name="io-cpp-view-widget-modifications"></a> +<p> The <tt>ReadDB()</tt> and \s SaveDB() implementations in <tt>io.cpp</tt> are +renamed to <tt>MainWindow::readDB()</tt> and <tt>MainWindow::saveDB()</tt>, +respectively. We need to modify the code in order to make the code +work properly. +<p> First, We add <tt>#include</tt> statements for the <tt>MainWindow</tt>, <a href="qspinbox.html">TQSpinBox</a> +and <a href="qtextedit.html">TQTextEdit</a> classes. +<p> + +<pre></pre><pre></pre> +<p> The new <tt>MainWindow::readDB()</tt> and <tt>MainWindow::saveDB()</tt> functions +will not use any Xt/Motif functions, so we remove the Xt/Motif <tt>#include</tt> statements and the global variables <tt>notebook</tt> and <tt>textw</tt>. +These functions remain largely unchanged, maintaining compatibility +with previous versions. Also, the <tt>ReadDB()</tt> and <tt>SaveDB()</tt> +functions have been converted into <tt>MainWindow</tt> member functions, so +we can pass <em>this</em> as the <em>parent</em> argument to the <a href="qmessagebox.html">TQMessageBox</a> +functions. +<p> <pre></pre> +<p> After reading the file in the <tt>MainWindow::readDB()</tt> function, we set +the current and maximum values of the <tt>spinbox</tt> to the appropriate +values. +<p> + +<p> <pre></pre> +<p> In the <tt>MainWindow::saveDB()</tt> function, we need to store the text +currently displayed, so we use <a href="qtextedit.html#text">TQTextEdit::text</a>() instead of <tt>XmTextGetString()</tt>. Note: TQTextEdit::text() returns a <a href="qstring.html">TQString</a>, which +needs to be converted into a normal <tt>char*</tt> array. To do this we +create a copy of the string in the local encoding. We need to make +the copy using <a href="qcstring.html#qstrdup">qstrdup</a>() because the data contained in the <a href="qcstring.html">TQCString</a> +returned by <a href="qstring.html#local8Bit">TQString::local8Bit</a>() is deallocated when the TQCString is +destroyed. +<p> <pre></pre> +<p> <a name="actions-cpp-viewwidget-modifications"></a> +<p> Due to the removal of the <tt>majorPB</tt> and <tt>minorPB</tt> members from the +<tt>Page</tt> struct, the <tt>FixPages()</tt> function in <tt>actions.cpp</tt> is no +longer needed. We remove the implementation and forward declaration +of <tt>FixPages()</tt> from <tt>actions.cpp</tt> and <tt>page.h</tt>, respectively. +Calls to <tt>FixPages()</tt> are removed from the <tt>MainWindow::selNewPage()</tt> and <tt>MainWindow::selDeletePage()</tt>, both of +which are in <tt>mainwindow.ui.h</tt>. +<p> We move <tt>AdjustPages()</tt> to <tt>mainwindow.ui.h</tt> and make it <tt>static</tt>, +since it is only used in this file. We remove the forward declaration +from <tt>page.h</tt> as well. +<p> After our modifications, the <tt>actions.cpp</tt> file is empty. We remove +it from our project file and regenerate our <tt>Makefile</tt>. +<p> <a name="todo-cpp-view-widget-modifications"></a> +<p> Now that we have implemented our new <em>View</em> widget, we need to remove +the old <a href="motif-extension.html#Motif">Motif</a> based view widget from <tt>todo.cpp</tt>. +<p> Since we will not be using any Motif widgets, we remove all Motif <tt>#include</tt> statements, including <a href="qmotifwidget-h.html">qmotifwidget.h</a>. +<p> + +<pre></pre><pre></pre> +<p> We also remove the forward declarations of the <tt>ReadDB()</tt> function +and the <tt>notebook</tt>, <tt>textw</tt> and <tt>labelw</tt> global variables. +<p> <pre></pre> +<p> Next, we remove the <tt>center</tt> widget, which uses <a href="qmotifwidget.html">TQMotifWidget</a>. The <em>Main Window</em> widget and <em>View</em> widget are contained entirely in our +<tt>MainWindow</tt> class, so no extra initialization is needed after +creating the <tt>mainwindow</tt> widget. +<p> <pre></pre> +<p> Since the <tt>ReadDB()</tt> and <tt>SetPage()</tt> functions have been changed into +<tt>MainWindow</tt> member functions, we need to call them using our <tt>mainwindow</tt> instance. +<p> <pre></pre> +<p> The <em>View</em> widget has now been replaced. After building our project, +we confirm that the application works correctly. +<p> [ <a href="motif-walkthrough-7.html">Previous: Refactoring Existing Code</a> ] +[ <a href="motif-walkthrough.html">Home</a> ] +[ <a href="motif-walkthrough-9.html">Next: Replacing the Print Dialog</a> ] +<p> +<!-- eof --> +<p><address><hr><div align=center> +<table width=100% cellspacing=0 border=0><tr> +<td>Copyright © 2007 +<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a> +<td align=right><div align=right>TQt 3.3.8</div> +</table></div></address></body> +</html> |