68304caffe
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@14900 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
189 lines
6.2 KiB
TeX
189 lines
6.2 KiB
TeX
\section{\class{wxKeyEvent}}\label{wxkeyevent}
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This event class contains information about keypress (character) events.
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Notice that there are three different kinds of keyboard events in wxWindows:
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key down and up events and char events. The difference between the first two
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is clear - the first corresponds to a key press and the second to a key
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release - otherwise they are identical. Just note that if the key is
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maintained in a pressed state you will typically get a lot of (automatically
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generated) down events but only one up so it is wrong to assume that there is
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one up event corresponding to each down one.
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Both key events provide untranslated key codes while the char event carries
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the translated one. The untranslated code for alphanumeric keys is always
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an upper case value. For the other keys it is one of {\tt WXK\_XXX} values
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from the \helpref{keycodes table}{keycodes}. The translated key is, in
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general, the character the user expects to appear as the result of the key
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combination when typing the text into a text entry zone, for example.
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If the key up event is caught and the event handler does not call
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event.Skip() then the coresponding char event will not happen. This
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is by design and enables the programs that handle both types of events
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to be a bit simpler.
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A few examples to clarify this (all assume that {\sc Caps Lock} is unpressed
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and the standard US keyboard): when the {\tt 'A'} key is pressed, the key down
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event key code is equal to {\tt ASCII A} $== 65$. But the char event key code
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is {\tt ASCII a} $== 97$. On the other hand, if you press both {\sc Shift} and
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{\tt 'A'} keys simultaneously , the key code in key down event will still be
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just {\tt 'A'} while the char event key code parameter will now be {\tt 'A'}
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as well.
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Although in this simple case it is clear that the correct key code could be
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found in the key down event handler by checking the value returned by
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\helpref{ShiftDown()}{wxkeyeventshiftdown}, in general you should use
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{\tt EVT\_CHAR} for this as for non alphanumeric keys the translation is
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keyboard-layout dependent and can only be done properly by the system itself.
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Another kind of translation is done when the control key is pressed: for
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example, for {\sc Ctrl-A} key press the key down event still carries the
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same key code {\tt 'a'} as usual but the char event will have key code of
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$1$, the ASCII value of this key combination.
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You may discover how the other keys on your system behave interactively by
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running the \helpref{text}{sampletext} wxWindows sample and pressing some keys
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in any of the text controls shown in it.
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{\bf Note for Windows programmers:} The key and char events in wxWindows are
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similar to but slightly different from Windows {\tt WM\_KEYDOWN} and
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{\tt WM\_CHAR} events. In particular, Alt-x combination will generate a char
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event in wxWindows (unless it is used as an acclerator).
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\wxheading{Derived from}
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\helpref{wxEvent}{wxevent}
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\wxheading{Include files}
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<wx/event.h>
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\wxheading{Event table macros}
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To process a key event, use these event handler macros to direct input to member
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functions that take a wxKeyEvent argument.
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\twocolwidtha{7cm}
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\begin{twocollist}\itemsep=0pt
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\twocolitem{{\bf EVT\_KEY\_DOWN(func)}}{Process a wxEVT\_KEY\_DOWN event (any key has been pressed).}
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\twocolitem{{\bf EVT\_KEY\_UP(func)}}{Process a wxEVT\_KEY\_UP event (any key has been released).}
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\twocolitem{{\bf EVT\_CHAR(func)}}{Process a wxEVT\_CHAR event.}
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%\twocolitem{{\bf EVT\_CHAR\_HOOK(func)}}{Process a wxEVT\_CHAR\_HOOK event.}
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\end{twocollist}%
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\latexignore{\rtfignore{\wxheading{Members}}}
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\membersection{wxKeyEvent::m\_altDown}
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\member{bool}{m\_altDown}
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TRUE if the Alt key is pressed down.
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\membersection{wxKeyEvent::m\_controlDown}
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\member{bool}{m\_controlDown}
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TRUE if control is pressed down.
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\membersection{wxKeyEvent::m\_keyCode}
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\member{long}{m\_keyCode}
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Virtual keycode. See \helpref{Keycodes}{keycodes} for a list of identifiers.
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\membersection{wxKeyEvent::m\_metaDown}
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\member{bool}{m\_metaDown}
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TRUE if the Meta key is pressed down.
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\membersection{wxKeyEvent::m\_shiftDown}
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\member{bool}{m\_shiftDown}
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TRUE if shift is pressed down.
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\membersection{wxKeyEvent::m\_x}
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\member{int}{m\_x}
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X position of the event.
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\membersection{wxKeyEvent::m\_y}
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\member{int}{m\_y}
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Y position of the event.
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\membersection{wxKeyEvent::wxKeyEvent}
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\func{}{wxKeyEvent}{\param{WXTYPE}{ keyEventType}}
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Constructor. Currently, the only valid event types are wxEVT\_CHAR and wxEVT\_CHAR\_HOOK.
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\membersection{wxKeyEvent::AltDown}
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\constfunc{bool}{AltDown}{\void}
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Returns TRUE if the Alt key was down at the time of the key event.
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\membersection{wxKeyEvent::ControlDown}
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\constfunc{bool}{ControlDown}{\void}
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Returns TRUE if the control key was down at the time of the key event.
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\membersection{wxKeyEvent::GetKeyCode}
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\constfunc{int}{GetKeyCode}{\void}
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Returns the virtual key code. ASCII events return normal ASCII values,
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while non-ASCII events return values such as {\bf WXK\_LEFT} for the
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left cursor key. See \helpref{Keycodes}{keycodes} for a full list of the virtual key codes.
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\membersection{wxKeyEvent::GetX}
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\constfunc{long}{GetX}{\void}
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Returns the X position of the event.
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\membersection{wxKeyEvent::GetY}
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\constfunc{long}{GetY}{\void}
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Returns the Y position of the event.
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\membersection{wxKeyEvent::MetaDown}
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\constfunc{bool}{MetaDown}{\void}
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Returns TRUE if the Meta key was down at the time of the key event.
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\membersection{wxKeyEvent::GetPosition}
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\constfunc{wxPoint}{GetPosition}{\void}
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\constfunc{void}{GetPosition}{\param{long *}{x}, \param{long *}{y}}
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Obtains the position at which the key was pressed.
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\membersection{wxKeyEvent::HasModifiers}
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\constfunc{bool}{HasModifiers}{\void}
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Returns TRUE if either {\sc Ctrl} or {\sc Alt} keys was down
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at the time of the key event. Note that this function does not take into
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account neither {\sc Shift} nor {\sc Meta} key states (the reason for ignoring
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the latter is that it is common for {\sc NumLock} key to be configured as
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{\sc Meta} under X but the key presses even while {\sc NumLock} is on should
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be still processed normally).
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\membersection{wxKeyEvent::ShiftDown}\label{wxkeyeventshiftdown}
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\constfunc{bool}{ShiftDown}{\void}
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Returns TRUE if the shift key was down at the time of the key event.
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