a660d684ed
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@11 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
86 lines
2.8 KiB
TeX
86 lines
2.8 KiB
TeX
\section{\class{wxCommand}}\label{wxcommand}
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wxCommand is a base class for modelling an application command,
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which is an action usually performed by selecting a menu item, pressing
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a toolbar button or any other means provided by the application to
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change the data or view.
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\wxheading{Derived from}
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\helpref{wxObject}{wxobject}
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\wxheading{See also}
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\overview{Overview}{wxcommandoverview}
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\latexignore{\rtfignore{\wxheading{Members}}}
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\membersection{wxCommand::wxCommand}
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\func{}{wxCommand}{\param{bool}{ canUndo = FALSE}, \param{const wxString\& }{name = NULL}}
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Constructor. wxCommand is an abstract class, so you will need to derive
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a new class and call this constructor from your own constructor.
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{\it canUndo} tells the command processor whether this command is undo-able. You
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can achieve the same functionality by overriding the CanUndo member function (if for example
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the criteria for undoability is context-dependant).
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{\it name} must be supplied for the command processor to display the command name
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in the application's edit menu.
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\membersection{wxCommand::\destruct{wxCommand}}
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\func{}{\destruct{wxCommand}}{\void}
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Destructor.
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\membersection{wxCommand::CanUndo}
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\func{bool}{CanUndo}{\void}
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Returns TRUE if the command can be undone, FALSE otherwise.
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\membersection{wxCommand::Do}
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\func{bool}{Do}{\void}
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Override this member function to execute the appropriate action when called.
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Return TRUE to indicate that the action has taken place, FALSE otherwise.
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Returning FALSE will indicate to the command processor that the action is
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not undoable and should not be added to the command history.
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\membersection{wxCommand::GetName}
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\func{wxString}{GetName}{\void}
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Returns the command name.
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\membersection{wxCommand::Undo}
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\func{bool}{Undo}{\void}
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Override this member function to un-execute a previous Do.
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Return TRUE to indicate that the action has taken place, FALSE otherwise.
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Returning FALSE will indicate to the command processor that the action is
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not redoable and no change should be made to the command history.
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How you implement this command is totally application dependent, but typical
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strategies include:
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\begin{itemize}\itemsep=0pt
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\item Perform an inverse operation on the last modified piece of
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data in the document. When redone, a copy of data stored in command
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is pasted back or some operation reapplied. This relies on the fact that
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you know the ordering of Undos; the user can never Undo at an arbitrary position
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in the command history.
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\item Restore the entire document state (perhaps using document transactioning).
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Potentially very inefficient, but possibly easier to code if the user interface
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and data are complex, and an `inverse execute' operation is hard to write.
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\end{itemize}
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The docview sample uses the first method, to remove or restore segments
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in the drawing.
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