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<table border="0" cellspacing="0" cellpadding="3" width="100%"><tr><td> <div align="center" id="bldcontent"> <a href="../default.htm"><img src="../images/opendocs.png" width="63" height="76" border="0"></a> <br> <div class="symbol">Your OpenSource Publisher™</div> </div> </td></tr></table> <div align="center" class="author"> <a href="../products.lxp">Products</a> | <a href="../wheretobuy.lxp">Where to buy</a> | <a href="../bookstore.lxp">Retailers</a> | <a href="../faq.lxp">FAQ</a> | <a href="../writeforus.lxp">Write for Us.</a> | <a href="#contact">Contact Us.</a> </div> <table border="0" cellspacing="3" cellpadding="0" width="100%"><tr><td width="100%"> <div class="content"> <table border="0" cellspacing="2" cellpadding="0" width="100%"><tr><td width="100%"> <div align="center"><H4 CLASS="AUTHOR"><A NAME="AEN5">Boudewijn Rempt</A><br><a href="../../https@secure.linuxports.com/opendocs/default.htm"><img src=odpyqt125.png></a><br>ISBN: 0-97003300-4-4<br><a href="../../https@secure.linuxports.com/opendocs/default.htm">Available from bookstores everywhere or you can order it here.</a><p>You can download the source files for the book <a href="pyqtsrc.tgz">(code / eps) here.</a><hr></div> <HTML><HEAD><TITLE>Undo, redo and other editing functions</TITLE><METANAME="GENERATOR"CONTENT="Modular DocBook HTML Stylesheet Version 1.72"><LINKREL="HOME"TITLE="GUI Programming with Python: QT Edition"HREF="book1.htm"><LINKREL="UP"TITLE="Creating Application Functionality"HREF="c5783.htm"><LINKREL="PREVIOUS"TITLE="Saving and loading documents"HREF="x5925.htm"><LINKREL="NEXT"TITLE="Conclusion"HREF="x6008.htm"></HEAD><BODYCLASS="SECT1"BGCOLOR="#FFFFFF"TEXT="#000000"LINK="#0000FF"VLINK="#840084"ALINK="#0000FF"><DIVCLASS="NAVHEADER"><TABLESUMMARY="Header navigation table"WIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><THCOLSPAN="3"ALIGN="center">GUI Programming with Python: QT Edition</TH></TR><TR><TDWIDTH="10%"ALIGN="left"VALIGN="bottom"><A accesskey="P" href="index.lxp@lxpwrap=x5925_252ehtm.htm">Prev</A></TD><TDWIDTH="80%"ALIGN="center"VALIGN="bottom">Chapter 17. Creating Application Functionality</TD><TDWIDTH="10%"ALIGN="right"VALIGN="bottom"><A accesskey="N" href="index.lxp@lxpwrap=x6008_252ehtm.htm">Next</A></TD></TR></TABLE><HRALIGN="LEFT"WIDTH="100%"></DIV><DIVCLASS="SECT1"><H1CLASS="SECT1">Undo, redo and other editing functions</A></H1><P>The editing component we are using, <TTCLASS="CLASSNAME">QMultiLineEdit</TT>, already supports undo and redo using standard keys. Because undo and redo are defined as slots in the C++ source for <TTCLASS="CLASSNAME">QMultiLineEdit</TT>, they immediately affect the document and all views. The only thing left for us is to add these functions to the edit menu and the toolbar. The same principle holds for cut, copy, paste and select all.</P><P>The right place for these additions is the central application class, <TTCLASS="CLASSNAME">KalamApp</TT>. However, we need to do more than simply connect the correct <TTCLASS="CLASSNAME">QAction</TT>s to the relevant slots in the view's editors. If we do that, then undo, for instance, would undo the last action in all views, simultaneously! We need to write special functions in <TTCLASS="CLASSNAME">KalamApp</TT> that work only on the active view, and we must wrap the <TTCLASS="CLASSNAME">QMultiLineEdit</TT> slots in the view component.</P><P>First the <TTCLASS="CLASSNAME">KalamView</TT> wrappings:</P><PRECLASS="PROGRAMLISTING"> def clear(self): self.editor.clear() def append(self, s): self.editor.append(s) def deselect(self): self.editor.deselect() def selectAll(self): self.editor.selectAll() def paste(self): self.editor.paste() def copy(self): self.editor.copy() def cut(self): self.editor.cut() def insert(self, s): self.editor.insert(s) def undo(self): self.editor.undo() def redo(self): self.editor.redo() </PRE><P>Of course, this initially looks very silly, and we could just as well directly call the <TTCLASS="CLASSNAME">QMultiLineEdit</TT> <TTCLASS="VARNAME">editor</TT> object variable — but by encapsulating the editor component we are free to substitute another component without having to hack the other components of the application.</P><P>The other changes are in the <TTCLASS="CLASSNAME">KalamApp</TT> class. First, a set of <TTCLASS="CLASSNAME">QAction</TT>s is added to the dictionary of actions.</P><P>Some of these actions have an associated toolbar or menubar icon defined. The icon data is defined in the <TTCLASS="FILENAME">resources.py</TT> file. I've used the GPL'ed toolbar icons from the KDE project. It is always a good idea to blend in as closely to the desktop environment you are targetting, so you might also want to provide a set of Windows standard icons and make it a configuration option which set should be used.</P><P>I do not show the full code, just the bits that are new compared to the previous chapter:</P><PRECLASS="PROGRAMLISTING"> def initActions(self): self.actions = {} ... # # Edit actions # self.actions["editClear"] = QAction("Clear", "C&lear", QAccel.stringToKey(""), self) self.connect(self.actions["editClear"], SIGNAL("activated()"), self.slotEditClear) self.actions["editSelectAll"] = QAction("SelectAll", "&SelectAll", QAccel.stringToKey(""), self) self.connect(self.actions["editSelectAll"], SIGNAL("activated()"), self.slotEditSelectAll) self.actions["editDeselect"] = QAction("Deselect", "Clear selection", QAccel.stringToKey(""), self) self.connect(self.actions["editDeselect"], SIGNAL("activated()"), self.slotEditDeselect) self.actions["editCut"] = QAction("Cut", QIconSet(QPixmap(editcut)), "C&ut", QAccel.stringToKey(""), self) self.connect(self.actions["editCut"], SIGNAL("activated()"), self.slotEditCut) self.actions["editCopy"] = QAction("Copy", QIconSet(QPixmap(editcopy)), "&Copy", QAccel.stringToKey(""), self) self.connect(self.actions["editCopy"], SIGNAL("activated()"), self.slotEditCopy) self.actions["editPaste"] = QAction("Paste", QIconSet(QPixmap(editpaste)), "&Paste", QAccel.stringToKey(""), self) self.connect(self.actions["editPaste"], SIGNAL("activated()"), self.slotEditPaste) self.actions["editInsert"] = QAction("Insert", "&Insert", QAccel.stringToKey(""), self) self.connect(self.actions["editInsert"], SIGNAL("activated()"), self.slotEditInsert) self.actions["editUndo"] = QAction("Undo", QIconSet(QPixmap(editundo)), "&Undo", QAccel.stringToKey("CTRL+Z"), self) self.connect(self.actions["editUndo"], SIGNAL("activated()"), self.slotEditUndo) self.actions["editRedo"] = QAction("Redo", QIconSet(QPixmap(editredo)), "&Redo", QAccel.stringToKey("CTRL+R"), self) self.connect(self.actions["editRedo"], SIGNAL("activated()"), self.slotEditRedo) </PRE><P>As you can see, there is still a fair amount of drudgery involved in creating a GUI interface. Qt 3.0 provides an extended GUI Designer that lets you design actions, menubars and toolbars with a comfortable interface.</P><P>For now, we'll have to distribute the actions by hand in the <TTCLASS="FUNCTION">initMenu()</TT> and <TTCLASS="FUNCTION">initToolbar()</TT> functions. Again, omitted code is elided with three dots (...).</P><PRECLASS="PROGRAMLISTING"> def initMenuBar(self): ... self.editMenu = QPopupMenu() self.actions["editUndo"].addTo(self.editMenu) self.actions["editRedo"].addTo(self.editMenu) self.editMenu.insertSeparator() self.actions["editCut"].addTo(self.editMenu) self.actions["editCopy"].addTo(self.editMenu) self.actions["editPaste"].addTo(self.editMenu) self.actions["editSelectAll"].addTo(self.editMenu) self.actions["editDeselect"].addTo(self.editMenu) self.actions["editClear"].addTo(self.editMenu) self.menuBar().insertItem("&Edit", self.editMenu) ... def initToolBar(self): ... self.editToolbar = QToolBar(self, "edit operations") self.actions["editUndo"].addTo(self.editToolbar) self.actions["editRedo"].addTo(self.editToolbar) self.actions["editCut"].addTo(self.editToolbar) self.actions["editCopy"].addTo(self.editToolbar) self.actions["editPaste"].addTo(self.editToolbar) ... </PRE><P>Finally, we have to define the actual slots called by the <TTCLASS="CLASSNAME">QAction</TT> objects. Note that we are not working directly on the document — if we did, then all actions (such as selecting text) would apply to all views of the document. We would also have to code an undo-redo stack ourselves. Instead, we retrieve the active view from the workspace manager, and work on that. This view will pass the command on to the <TTCLASS="CLASSNAME">QMultiLineEdit</TT> object, and propagate all changes to the relevant document.</P><PRECLASS="PROGRAMLISTING"> # Edit slots def slotEditClear(self): self.workspace.activeWindow().clear() def slotEditDeselect(self): self.workspace.activeWindow().deselect() def slotEditSelectAll(self): self.workspace.activeWindow().selectAll() def slotEditPaste(self): self.workspace.activeWindow().paste() def slotEditCopy(self): self.workspace.activeWindow().copy() def slotEditCut(self): self.workspace.activeWindow().cut() def slotEditInsert(self): self.workspace.activeWindow().insert() def slotEditUndo(self): self.workspace.activeWindow().undo() def slotEditRedo(self): self.workspace.activeWindow().redo() </PRE></DIV><DIVCLASS="NAVFOOTER"><HRALIGN="LEFT"WIDTH="100%"><TABLESUMMARY="Footer navigation table"WIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top"><A accesskey="P" href="index.lxp@lxpwrap=x5925_252ehtm.htm">Prev</A></TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><A accesskey="H" href="index.lxp@lxpwrap=book1_252ehtm">Home</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top"><A accesskey="N" href="index.lxp@lxpwrap=x6008_252ehtm.htm">Next</A></TD></TR><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top">Saving and loading documents</TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><A accesskey="U" href="index.lxp@lxpwrap=c5783_252ehtm.htm">Up</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top">Conclusion</TD></TR></TABLE></DIV></BODY></HTML> </td> </tr> </table> </td> </tr> </table> ⌨️ 快捷键说明
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