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| author | Timothy Pearson <kb9vqf@pearsoncomputing.net> | 2011-11-08 12:31:36 -0600 |
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| committer | Timothy Pearson <kb9vqf@pearsoncomputing.net> | 2011-11-08 12:31:36 -0600 |
| commit | d796c9dd933ab96ec83b9a634feedd5d32e1ba3f (patch) | |
| tree | 6e3dcca4f77e20ec8966c666aac7c35bd4704053 /doc/html/simple-application.html | |
| download | tqt3-d796c9dd933ab96ec83b9a634feedd5d32e1ba3f.tar.gz tqt3-d796c9dd933ab96ec83b9a634feedd5d32e1ba3f.zip | |
Test conversion to TQt3 from Qt3 8c6fc1f8e35fd264dd01c582ca5e7549b32ab731
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| -rw-r--r-- | doc/html/simple-application.html | 575 |
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diff --git a/doc/html/simple-application.html b/doc/html/simple-application.html new file mode 100644 index 000000000..239908cd7 --- /dev/null +++ b/doc/html/simple-application.html @@ -0,0 +1,575 @@ +<!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/doc/application-walkthrough.doc:36 --> +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> +<title>Walkthrough: A Simple Application</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>Walkthrough: A Simple Application</h1> + + + +<p> +<p> This walkthrough shows simple use of <a href="qmainwindow.html">TQMainWindow</a>, <a href="qmenubar.html">TQMenuBar</a>, <a href="qpopupmenu.html">TQPopupMenu</a>, <a href="qtoolbar.html">TQToolBar</a> and <a href="qstatusbar.html">TQStatusBar</a> - classes that every +modern application window tends to use. (See also <a href="tutorial2.html">Tutorial #2</a>.) +<p> It also illustrates some aspects of <a href="qwhatsthis.html">TQWhatsThis</a> (for simple help) and a +typical <tt>main()</tt> using <a href="qapplication.html">TQApplication</a>. +<p> Finally, it shows a typical print function based on <a href="qprinter.html">TQPrinter</a>. +<p> <h2> The declaration of ApplicationWindow +</h2> +<a name="1"></a><p> Here's the header file in full: +<p> <pre>/**************************************************************************** +** $Id: qt/application.h 3.3.8 edited Jan 11 14:37 $ +** +** Copyright (C) 1992-2007 Trolltech ASA. All rights reserved. +** +** This file is part of an example program for TQt. This example +** program may be used, distributed and modified without limitation. +** +*****************************************************************************/ + +#ifndef APPLICATION_H +#define APPLICATION_H + +#include <<a href="qmainwindow-h.html">qmainwindow.h</a>> + +class TQTextEdit; + +class ApplicationWindow: public <a href="qmainwindow.html">TQMainWindow</a> +{ + <a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a> + +public: + ApplicationWindow(); + ~ApplicationWindow(); + +protected: + void closeEvent( <a href="qcloseevent.html">TQCloseEvent</a>* ); + +private slots: + void newDoc(); + void choose(); + void load( const <a href="qstring.html">TQString</a> &fileName ); + void save(); + void saveAs(); + void print(); + + void about(); + void aboutTQt(); + +private: + <a href="qprinter.html">TQPrinter</a> *printer; + <a href="qtextedit.html">TQTextEdit</a> *e; + <a href="qstring.html">TQString</a> filename; +}; + + +#endif +</pre> + +<p> It declares a class that inherits <a href="qmainwindow.html">TQMainWindow</a>, with slots and private +variables. The class pre-declaration of <a href="qtextedit.html">TQTextEdit</a> at the beginning +(instead of an include) helps to speed up compilation. With this +trick, <tt>make depend</tt> won't insist on recompiling every <tt>.cpp</tt> file that +includes <tt>application.h</tt> when <a href="qtextedit-h.html">qtextedit.h</a> changes. +<p> <a name="simplemain"></a> +<h2> A simple main() +</h2> +<a name="2"></a><p> Here is <tt>main.cpp</tt> in full: +<p> <pre>/**************************************************************************** +** $Id: qt/main.cpp 3.3.8 edited Jan 11 14:37 $ +** +** Copyright (C) 1992-2007 Trolltech ASA. All rights reserved. +** +** This file is part of an example program for TQt. This example +** program may be used, distributed and modified without limitation. +** +*****************************************************************************/ + +#include <<a href="qapplication-h.html">qapplication.h</a>> +#include "application.h" + +int main( int argc, char ** argv ) { + <a href="qapplication.html">TQApplication</a> a( argc, argv ); + ApplicationWindow *mw = new ApplicationWindow(); + mw-><a href="qwidget.html#setCaption">setCaption</a>( "TQt Example - Application" ); +<a name="x1598"></a> mw-><a href="qwidget.html#show">show</a>(); +<a name="x1599"></a> a.<a href="qobject.html#connect">connect</a>( &a, SIGNAL(<a href="qapplication.html#lastWindowClosed">lastWindowClosed</a>()), &a, SLOT(<a href="qapplication.html#tquit">tquit</a>()) ); + return a.<a href="qapplication.html#exec">exec</a>(); +} +</pre> + +<p> Now we'll look at <tt>main.cpp</tt> in detail. +<p> + +<pre> int main( int argc, char ** argv ) { + <a href="qapplication.html">TQApplication</a> a( argc, argv ); +</pre> +<p> With the above line, we create a <a href="qapplication.html">TQApplication</a> object with the usual +constructor and let it +parse <em>argc</em> and <em>argv</em>. TQApplication itself takes care of X11-specific +command-line options like <em>-geometry</em>, so the program will automatically +behave the way X clients are expected to. +<p> <pre> ApplicationWindow *mw = new ApplicationWindow(); + mw-><a href="qwidget.html#setCaption">setCaption</a>( "TQt Example - Application" ); + <a name="x2115"></a> mw-><a href="qwidget.html#show">show</a>(); +</pre> +<p> We create an <em>ApplicationWindow</em> as a top-level widget, set its window +system caption to "Document 1", and <em>show()</em> it. +<p> <a name="close"></a> +<pre> a.<a href="qobject.html#connect">connect</a>( &a, SIGNAL(<a href="qapplication.html#lastWindowClosed">lastWindowClosed</a>()), &a, SLOT(<a href="qapplication.html#tquit">tquit</a>()) ); +</pre> +<p> When the application's last window is closed, it should tquit. Both +the signal and the slot are predefined members of <a href="qapplication.html">TQApplication</a>. +<p> <pre> return a.<a href="qapplication.html#exec">exec</a>(); +</pre> +<p> Having completed the application's initialization, we start the main +event loop (the GUI), and eventually return the error code +that TQApplication returns when it leaves the event loop. +<p> <pre> } +</pre> +<p> <a name="ApplicationWindow"></a> +<h2> The Implementation of ApplicationWindow +</h2> +<a name="3"></a><p> + +<p> Since the implementation is tquite large (almost 300 lines) we +won't list the whole thing. (The source code is included in the +examples/application directory.) Before we start with the constructor +there are three <tt>#include</tt>s worth mentioning: +<p> <pre> #include "filesave.xpm" + #include "fileopen.xpm" + #include "fileprint.xpm" +</pre> +<p> The tool buttons in our application wouldn't look good without icons! +These icons can be found in the XPM files included above. If you ever +moved a program to a different location and wondered why icons were +missing afterwards you will probably agree that it is a good idea to +compile them into the binary. This is what we are doing here. +<p> <pre> ApplicationWindow::ApplicationWindow() + : <a href="qmainwindow.html">TQMainWindow</a>( 0, "example application main window", WDestructiveClose | WGroupLeader ) + { +</pre> +<p> <em>ApplicationWindow</em> inherits <a href="qmainwindow.html">TQMainWindow</a>, the TQt class that provides +typical application main windows, with menu bars, toolbars, etc. +<p> <pre> printer = new <a href="qprinter.html">TQPrinter</a>( TQPrinter::HighResolution ); +</pre> +<p> The application example can print things, and we chose to have a +<a href="qprinter.html">TQPrinter</a> object lying around so that when the user changes a setting +during one printing, the new setting will be the default next time. +<p> <pre> <a href="qpixmap.html">TQPixmap</a> openIcon, saveIcon, printIcon; +</pre> +<p> For the sake of simplicity, our example only has a few commands in the +toolbar. The above variables are used to hold an icon for each of +them. +<p> <pre> <a href="qtoolbar.html">TQToolBar</a> * fileTools = new <a href="qtoolbar.html">TQToolBar</a>( this, "file operations" ); +</pre> +<p> We create a toolbar in <em>this</em> window ... +<p> <pre> fileTools-><a href="qtoolbar.html#setLabel">setLabel</a>( "File Operations" ); +</pre> +<p> ... and define a title for it. When a user drags the toolbar out of +its location and floats it over the desktop, the toolbar-window will +show "File Operations" as caption. +<p> <pre> openIcon = TQPixmap( fileopen ); + TQToolButton * fileOpen + = new <a href="qtoolbutton.html">TQToolButton</a>( openIcon, "Open File", <a href="qstring.html#TQString-null">TQString::null</a>, + this, SLOT(choose()), fileTools, "open file" ); +</pre> +<p> Now we create the first tool button for the <em>fileTools</em> toolbar +with the appropriate icon and the tool-tip text "Open File". +The <tt>fileopen.xpm</tt> we included at the beginning +contains the definition of a pixmap called <em>fileopen</em>. +We use this icon to illustrate our first tool button. +<p> <pre> saveIcon = TQPixmap( filesave ); + TQToolButton * fileSave + = new <a href="qtoolbutton.html">TQToolButton</a>( saveIcon, "Save File", TQString::null, + this, SLOT(save()), fileTools, "save file" ); + + printIcon = TQPixmap( fileprint ); + TQToolButton * filePrint + = new <a href="qtoolbutton.html">TQToolButton</a>( printIcon, "Print File", TQString::null, + this, SLOT(print()), fileTools, "print file" ); +</pre> +<p> In a similar way we create two more tool buttons in this toolbar, each with +appropriate icons and tool-tip text. All three buttons are connected +to appropriate slots in this object; for example, the "Print File" button +to <a href="#printer">ApplicationWindow::print()</a>. +<p> <pre> (void)TQWhatsThis::whatsThisButton( fileTools ); +</pre> +<p> The fourth button in the toolbar is somewhat peculiar: it's the one that +provides "What's This?" help. This must be set up using a special +function, as its mouse interface is unusual. +<p> <pre> const char * fileOpenText = "<p><img source=\"fileopen\"> " + "Click this button to open a <em>new file</em>.<br>" + "You can also select the <b>Open</b> command " + "from the <b>File</b> menu.</p>"; + + TQWhatsThis::<a href="qwhatsthis.html#add">add</a>( fileOpen, fileOpenText ); +</pre> +<p> With the above line we add the "What's This?" help-text to the +<em>fileOpen</em> button... +<p> <pre> TQMimeSourceFactory::<a href="qmimesourcefactory.html#defaultFactory">defaultFactory</a>()->setPixmap( "fileopen", openIcon ); +</pre> +<p> ... and tell the rich-text engine that when a help-text (like the one +saved in <em>fileOpenText</em>) requests an image named "fileopen", the <em>openIcon</em> pixmap is used. +<p> <pre> const char * fileSaveText = "<p>Click this button to save the file you " + "are editing. You will be prompted for a file name.\n" + "You can also select the <b>Save</b> command " + "from the <b>File</b> menu.</p>"; + + TQWhatsThis::<a href="qwhatsthis.html#add">add</a>( fileSave, fileSaveText ); + const char * filePrintText = "Click this button to print the file you " + "are editing.\n" + "You can also select the Print command " + "from the File menu."; + + TQWhatsThis::<a href="qwhatsthis.html#add">add</a>( filePrint, filePrintText ); +</pre> +<p> The "What's This?" help of the remaining two buttons doesn't make use +of pixmaps, therefore all we need to do is to add the help-text to the +button. Be careful though: To invoke the rich-text elements in <tt>fileSaveText()</tt>, the entire string must be surrounded by <p> and +</p>. In <tt>filePrintText()</tt>, we don't have rich-text elements, so +this is not necessary. +<p> <pre> <a href="qpopupmenu.html">TQPopupMenu</a> * file = new <a href="qpopupmenu.html">TQPopupMenu</a>( this ); + <a href="qmainwindow.html#menuBar">menuBar</a>()->insertItem( "&File", file ); +</pre> +<p> Next we create a <a href="qpopupmenu.html">TQPopupMenu</a> for the <em>File</em> menu and +add it to the menu bar. With the ampersand in front of the letter F, +we allow the user to use the shortcut <em>Alt+F</em> to pop up this menu. +<p> <pre> file-><a href="qmenudata.html#insertItem">insertItem</a>( "&New", this, SLOT(newDoc()), CTRL+Key_N ); +</pre> +<p> Its first entry is connected to the (yet to be implemented) slot <tt>newDoc()</tt>. When the user chooses this <em>New</em> entry (e.g. by typing the +letter N as marked by the ampersand) or uses the +<em>Ctrl+N</em> accelerator, a new editor-window will pop up. +<p> <pre> int id; + id = file-><a href="qmenudata.html#insertItem">insertItem</a>( openIcon, "&Open...", + this, SLOT(choose()), CTRL+Key_O ); + file-><a href="qmenudata.html#setWhatsThis">setWhatsThis</a>( id, fileOpenText ); + + id = file-><a href="qmenudata.html#insertItem">insertItem</a>( saveIcon, "&Save", + this, SLOT(save()), CTRL+Key_S ); + file-><a href="qmenudata.html#setWhatsThis">setWhatsThis</a>( id, fileSaveText ); + + id = file-><a href="qmenudata.html#insertItem">insertItem</a>( "Save &As...", this, SLOT(saveAs()) ); + file-><a href="qmenudata.html#setWhatsThis">setWhatsThis</a>( id, fileSaveText ); +</pre> +<p> We populate the <em>File</em> menu with three more commands (<em>Open</em>, <em>Save</em> and +<em>Save As</em>), and set "What's This?" help for them. Note in particular +that "What's This?" help and pixmaps are used in both the toolbar (above) +and the menu bar (here). (See <a href="qaction.html">TQAction</a> and the <tt>examples/action</tt> +example for a shorter and easier approach.) +<p> <pre> file-><a href="qmenudata.html#insertSeparator">insertSeparator</a>(); +</pre> +<p> Then we insert a separator, ... +<p> <pre> id = file-><a href="qmenudata.html#insertItem">insertItem</a>( printIcon, "&Print...", + this, SLOT(print()), CTRL+Key_P ); + file-><a href="qmenudata.html#setWhatsThis">setWhatsThis</a>( id, filePrintText ); + + file-><a href="qmenudata.html#insertSeparator">insertSeparator</a>(); + + file-><a href="qmenudata.html#insertItem">insertItem</a>( "&Close", this, SLOT(<a href="qwidget.html#close">close</a>()), CTRL+Key_W ); + file-><a href="qmenudata.html#insertItem">insertItem</a>( "&Quit", qApp, SLOT( <a href="qapplication.html#closeAllWindows">closeAllWindows</a>() ), CTRL+Key_Q ); +</pre> +<p> ... the <em>Print</em> command with "What's This?" help, another separator and +two more commands (<em>Close</em> and <em>Quit</em>) without "What's This?" and pixmaps. +In case of the <em>Close</em> command, the signal is connected +to the <em>close()</em> slot of the respective <em>ApplicationWindow</em> object whilst +the <em>Quit</em> command affects the entire application. +<p> Because <em>ApplicationWindow</em> is a <a href="qwidget.html">TQWidget</a>, the <em>close()</em> function +triggers a call to <a href="#closeEvent">closeEvent()</a> which we +will implement later. +<p> <a name="common_constructor"></a> +<pre> <a href="qmainwindow.html#menuBar">menuBar</a>()->insertSeparator(); +</pre> +<p> Now that we have done the File menu we shift our focus back to the +menu bar and insert a separator. From now on further menu bar entries +will be aligned to the right if the windows system style retquires it. +<p> <pre> <a href="qpopupmenu.html">TQPopupMenu</a> * help = new <a href="qpopupmenu.html">TQPopupMenu</a>( this ); + <a href="qmainwindow.html#menuBar">menuBar</a>()->insertItem( "&Help", help ); + + help-><a href="qmenudata.html#insertItem">insertItem</a>( "&About", this, SLOT(about()), Key_F1 ); + help-><a href="qmenudata.html#insertItem">insertItem</a>( "About &TQt", this, SLOT(aboutTQt()) ); + help-><a href="qmenudata.html#insertSeparator">insertSeparator</a>(); + help-><a href="qmenudata.html#insertItem">insertItem</a>( "What's &This", this, SLOT(<a href="qmainwindow.html#whatsThis">whatsThis</a>()), SHIFT+Key_F1 ); +</pre> +<p> We create a <em>Help</em> menu, add it to the menu bar, and insert a few +commands. Depending on the style it will appear on the right hand +side of the menu bar or not. +<p> <pre> e = new <a href="qtextedit.html">TQTextEdit</a>( this, "editor" ); + e-><a href="qwidget.html#setFocus">setFocus</a>(); + <a href="qmainwindow.html#setCentralWidget">setCentralWidget</a>( e ); +</pre> +<p> Now we create a simple text-editor, set the initial focus to it, +and make it the window's central widget. +<p> <a href="qmainwindow.html#centralWidget">TQMainWindow::centralWidget</a>() is the heart of the entire application: +It's what menu bar, statusbar and toolbars are all arranged around. Since +the central widget is a text editing widget, we can now reveal that +our simple application is a text editor. :) +<p> <pre> <a href="qmainwindow.html#statusBar">statusBar</a>()->message( "Ready", 2000 ); +</pre> +<p> We make the statusbar say "Ready" for two seconds at startup, just to +tell the user that the window has finished initialization and can be +used. +<p> <pre> <a href="qwidget.html#resize">resize</a>( 450, 600 ); +</pre> +<p> Finally it's time to resize the new window to a a nice default size. +<p> <pre> } +</pre> +<p> We have now finished with the constructor. Now we'll deal with the +destructor. +<p> <pre> ApplicationWindow::~ApplicationWindow() + { + delete printer; + } +</pre> +<p> The only thing an <em>ApplicationWindow</em> widget needs to do in its +destructor is to delete the printer it created. All other objects are +child widgets, which TQt will delete when appropriate. +<p> Now our task is to implement all the slots mentioned in the header file +and used in the constructor. +<p> <a name="newDoc()"></a> +<pre> void ApplicationWindow::newDoc() + { + ApplicationWindow *ed = new ApplicationWindow; + ed-><a href="qwidget.html#setCaption">setCaption</a>("TQt Example - Application"); + ed-><a href="qwidget.html#show">show</a>(); + } +</pre> +<p> This slot, connected to the <em>File|New</em> menu item, simply creates a +new <em>ApplicationWindow</em> and shows it. +<p> <a name="choose()"></a> +<pre> void ApplicationWindow::choose() + { + <a href="qstring.html">TQString</a> fn = TQFileDialog::<a href="qfiledialog.html#getOpenFileName">getOpenFileName</a>( TQString::null, TQString::null, + this); + if ( !fn.<a href="qstring.html#isEmpty">isEmpty</a>() ) + load( fn ); + else + <a href="qmainwindow.html#statusBar">statusBar</a>()->message( "Loading aborted", 2000 ); + } +</pre> +<p> The <em>choose()</em> slot is connected to the <em>Open</em> menu item and +tool button. With a little help from <a href="qfiledialog.html#getOpenFileName">TQFileDialog::getOpenFileName</a>(), it +asks the user for a file name and then either loads that file or gives an +error message in the statusbar. +<p> <pre> void ApplicationWindow::load( const <a href="qstring.html">TQString</a> &fileName ) + { + <a href="qfile.html">TQFile</a> f( fileName ); + if ( !f.<a href="qfile.html#open">open</a>( <a href="qfile.html#open">IO_ReadOnly</a> ) ) + return; + + <a href="qtextstream.html">TQTextStream</a> ts( &f ); + e-><a href="qtextedit.html#setText">setText</a>( ts.<a href="qtextstream.html#read">read</a>() ); + e-><a href="qtextedit.html#setModified">setModified</a>( FALSE ); + <a href="qwidget.html#setCaption">setCaption</a>( fileName ); + <a href="qmainwindow.html#statusBar">statusBar</a>()->message( "Loaded document " + fileName, 2000 ); + } +</pre> +<p> This function loads a file into the editor. When it's done, it sets the +window system caption to the file name and displays a success message in +the statusbar for two seconds. With files that exist but are not +readable, nothing happens. +<p> <a name="save()"></a> +<pre> void ApplicationWindow::save() + { + if ( filename.isEmpty() ) { + saveAs(); + return; + } + + <a href="qstring.html">TQString</a> text = e-><a href="qtextedit.html#text">text</a>(); + <a href="qfile.html">TQFile</a> f( filename ); + if ( !f.<a href="qfile.html#open">open</a>( <a href="qfile.html#open">IO_WriteOnly</a> ) ) { + <a href="qmainwindow.html#statusBar">statusBar</a>()->message( TQString("Could not write to %1").arg(filename), + 2000 ); + return; + } + + <a href="qtextstream.html">TQTextStream</a> t( &f ); + t << text; + f.<a href="qfile.html#close">close</a>(); +</pre> +<p> As its name suggests, this function saves the current file. If no +filename has been specified so far, the <a href="#saveAs()">saveAs()</a> function is called. Unwritable files cause the <em>ApplicationWindow</em> object to provide an error-message in the statusbar. +Note that there is more than one way to do this: +compare the above <tt>statusBar()->message()</tt> line with the equivalent +code in the <tt>load()</tt> function. +<p> <pre> e-><a href="qtextedit.html#setModified">setModified</a>( FALSE ); +</pre> +<p> Tell the editor that the contents haven't been edited since the last +save. When the user does some further editing and wishes to close the +window without explicit saving, <a href="#closeEvent">ApplicationWindow::closeEvent()</a> will ask about it. +<p> <pre> <a href="qwidget.html#setCaption">setCaption</a>( filename ); +</pre> +<p> It may be that the document was saved under a different name than the +old caption suggests, so we set the window caption just to be sure. +<p> <pre> <a href="qmainwindow.html#statusBar">statusBar</a>()->message( TQString( "File %1 saved" ).arg( filename ), 2000 ); + } +</pre> +<p> With a message in the statusbar, we inform the user that the file +was saved successfully. +<p> <a name="saveAs()"></a> +<pre> void ApplicationWindow::saveAs() + { + <a href="qstring.html">TQString</a> fn = TQFileDialog::<a href="qfiledialog.html#getSaveFileName">getSaveFileName</a>( TQString::null, TQString::null, + this ); + if ( !fn.<a href="qstring.html#isEmpty">isEmpty</a>() ) { + filename = fn; + save(); + } else { + <a href="qmainwindow.html#statusBar">statusBar</a>()->message( "Saving aborted", 2000 ); + } + } +</pre> +<p> This function asks for a new name, saves the document under that name, +and implicitly changes the window system caption to the new name. +<p> <a name="printer"></a> +<p> <pre> void ApplicationWindow::print() + { + printer-><a href="qprinter.html#setFullPage">setFullPage</a>( TRUE ); + if ( printer-><a href="qprinter.html#setup">setup</a>(this) ) { // printer dialog + <a href="qmainwindow.html#statusBar">statusBar</a>()->message( "Printing..." ); + <a href="qpainter.html">TQPainter</a> p; + if( !p.<a href="qpainter.html#begin">begin</a>( printer ) ) { // paint on printer + <a href="qmainwindow.html#statusBar">statusBar</a>()->message( "Printing aborted", 2000 ); + return; + } + + <a href="qpaintdevicemetrics.html">TQPaintDeviceMetrics</a> metrics( p.<a href="qpainter.html#device">device</a>() ); + int dpiy = metrics.<a href="qpaintdevicemetrics.html#logicalDpiY">logicalDpiY</a>(); + int margin = (int) ( (2/2.54)*dpiy ); // 2 cm margins + <a href="qrect.html">TQRect</a> view( margin, margin, metrics.<a href="qpaintdevicemetrics.html#width">width</a>() - 2*margin, metrics.<a href="qpaintdevicemetrics.html#height">height</a>() - 2*margin ); + <a href="qsimplerichtext.html">TQSimpleRichText</a> richText( TQStyleSheet::<a href="qstylesheet.html#convertFromPlainText">convertFromPlainText</a>(e-><a href="qtextedit.html#text">text</a>()), + TQFont(), + e-><a href="qtextedit.html#context">context</a>(), + e-><a href="qtextedit.html#styleSheet">styleSheet</a>(), + e-><a href="qtextedit.html#mimeSourceFactory">mimeSourceFactory</a>(), + view.<a href="qrect.html#height">height</a>() ); + richText.<a href="qsimplerichtext.html#setWidth">setWidth</a>( &p, view.<a href="qrect.html#width">width</a>() ); + int page = 1; + do { + richText.<a href="qsimplerichtext.html#draw">draw</a>( &p, margin, margin, view, colorGroup() ); + view.<a href="qrect.html#moveBy">moveBy</a>( 0, view.<a href="qrect.html#height">height</a>() ); + p.<a href="qpainter.html#translate">translate</a>( 0 , -view.<a href="qrect.html#height">height</a>() ); + p.<a href="qpainter.html#drawText">drawText</a>( view.<a href="qrect.html#right">right</a>() - p.<a href="qpainter.html#fontMetrics">fontMetrics</a>().width( TQString::<a href="qstring.html#number">number</a>( page ) ), + view.<a href="qrect.html#bottom">bottom</a>() + p.<a href="qpainter.html#fontMetrics">fontMetrics</a>().ascent() + 5, TQString::number( page ) ); + if ( view.<a href="qrect.html#top">top</a>() - margin >= richText.<a href="qsimplerichtext.html#height">height</a>() ) + break; + printer-><a href="qprinter.html#newPage">newPage</a>(); + page++; + } while (TRUE); + + <a href="qmainwindow.html#statusBar">statusBar</a>()->message( "Printing completed", 2000 ); + } else { + <a href="qmainwindow.html#statusBar">statusBar</a>()->message( "Printing aborted", 2000 ); + } + } +</pre> +<p> <em>print()</em> is called by the <em>File|Print</em> menu item and the <em>filePrint</em> +tool button. +<p> We present the user with the print setup dialog, and abandon printing +if they cancel. +<p> We create a <a href="qsimplerichtext.html">TQSimpleRichText</a> object and give it the text. This object +is able to format the text nicely as one long page. We achieve +pagination by printing one paper page's worth of text from the +TQSimpleRichText page at a time. +<p> Now let's see what happens when a user wishes to <em>close()</em> +an <em>ApplicationWindow</em>. +<p> <a name="closeEvent"></a> +<pre> void ApplicationWindow::<a href="qwidget.html#closeEvent">closeEvent</a>( <a href="qcloseevent.html">TQCloseEvent</a>* ce ) + { +</pre> +<p> This event gets to process window system close events. A close event is +subtly different from a hide event: hide often means "iconify" whereas +close means that the window is going away for good. +<p> <pre> if ( !e-><a href="qtextedit.html#isModified">isModified</a>() ) { + ce-><a href="qcloseevent.html#accept">accept</a>(); + return; + } +</pre> +<p> If the text hasn't been edited, we just accept the event. The window +will be closed, and because we used the <em>WDestructiveClose</em> <a href="qt.html#WidgetFlags">widget flag</a> in the <a href="#ApplicationWindow"><i>ApplicationWindow()</i> constructor</a>, +the widget will be deleted. +<p> <pre> switch( TQMessageBox::<a href="qmessagebox.html#information">information</a>( this, "TQt Application Example", + "Do you want to save the changes" + " to the document?", + "Yes", "No", "Cancel", + 0, 1 ) ) { +</pre> +<p> Otherwise we ask the user: What do you want to do? +<p> <pre> case 0: + save(); + ce-><a href="qcloseevent.html#accept">accept</a>(); + break; +</pre> +<p> If they want to save and then exit, we do that. +<p> <pre> case 1: + ce-><a href="qcloseevent.html#accept">accept</a>(); + break; +</pre> +<p> If the user doesn't want to exit, we ignore the close event (there is +a chance that we can't block it but we try). +<p> <pre> case 2: + default: // just for sanity + ce-><a href="qcloseevent.html#ignore">ignore</a>(); + break; +</pre> +<p> The last case -- the user wants to abandon the edits and exit -- is very +simple. +<p> <pre> } + } +</pre> +<p> Last but not least we implement the slots used by the help menu entries. +<p> <pre> void ApplicationWindow::about() + { + TQMessageBox::<a href="qmessagebox.html#about">about</a>( this, "TQt Application Example", + "This example demonstrates simple use of " + "TQMainWindow,\nTQMenuBar and TQToolBar."); + } + + void ApplicationWindow::aboutTQt() + { + TQMessageBox::<a href="qmessagebox.html#aboutTQt">aboutTQt</a>( this, "TQt Application Example" ); + } +</pre> +<p> These two slots use ready-made "about" functions to provide some +information about this program and the GUI toolkit it uses. (Although you +don't need to provide an About TQt in your programs, if you use TQt for free +we would appreciate it if you tell people what you're using.) +<p> That was all we needed to write a complete, almost useful application with +nice help-functions, almost as good as the "editors" some computer vendors +ship with their desktops, and in less than 300 lines of code! +<p> <p>See also <a href="step-by-step-examples.html">Step-by-step Examples</a>. + +<!-- 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> |