docs/latex/wx/keyevent.tex

   1 \section{\class{wxKeyEvent}}\label{wxkeyevent}
   2
   3 This event class contains information about keypress (character) events.
   4
   5 Notice that there are three different kinds of keyboard events in wxWidgets:
   6 key down and up events and char events. The difference between the first two
   7 is clear - the first corresponds to a key press and the second to a key
   8 release - otherwise they are identical. Just note that if the key is
   9 maintained in a pressed state you will typically get a lot of (automatically
  10 generated) down events but only one up so it is wrong to assume that there is
  11 one up event corresponding to each down one.
  12
  13 Both key events provide untranslated key codes while the char event carries
  14 the translated one. The untranslated code for alphanumeric keys is always
  15 an upper case value. For the other keys it is one of {\tt WXK\_XXX} values
  16 from the \helpref{keycodes table}{keycodes}. The translated key is, in
  17 general, the character the user expects to appear as the result of the key
  18 combination when typing the text into a text entry zone, for example.
  19
  20 A few examples to clarify this (all assume that {\sc Caps Lock} is unpressed
  21 and the standard US keyboard): when the {\tt 'A'} key is pressed, the key down
  22 event key code is equal to {\tt ASCII A} $== 65$. But the char event key code
  23 is {\tt ASCII a} $== 97$. On the other hand, if you press both {\sc Shift} and
  24 {\tt 'A'} keys simultaneously , the key code in key down event will still be
  25 just {\tt 'A'} while the char event key code parameter will now be {\tt 'A'}
  26 as well.
  27
  28 Although in this simple case it is clear that the correct key code could be
  29 found in the key down event handler by checking the value returned by
  30 \helpref{ShiftDown()}{wxkeyeventshiftdown}, in general you should use
  31 {\tt EVT\_CHAR} for this as for non alphanumeric keys the translation is
  32 keyboard-layout dependent and can only be done properly by the system itself.
  33
  34 Another kind of translation is done when the control key is pressed: for
  35 example, for {\sc Ctrl-A} key press the key down event still carries the
  36 same key code {\tt 'a'} as usual but the char event will have key code of
  37 $1$, the ASCII value of this key combination.
  38
  39 You may discover how the other keys on your system behave interactively by
  40 running the \helpref{text}{sampletext} wxWidgets sample and pressing some keys
  41 in any of the text controls shown in it.
  42
  43 {\bf Note:} If a key down ({\tt EVT\_KEY\_DOWN}) event is caught and
  44 the event handler does not call {\tt event.Skip()} then the coresponding
  45 char event ({\tt EVT\_CHAR}) will not happen.  This is by design and
  46 enables the programs that handle both types of events to be a bit
  47 simpler.
  48
  49 {\bf Note for Windows programmers:} The key and char events in wxWidgets are
  50 similar to but slightly different from Windows {\tt WM\_KEYDOWN} and
  51 {\tt WM\_CHAR} events. In particular, Alt-x combination will generate a char
  52 event in wxWidgets (unless it is used as an accelerator).
  53
  54 {\bf Tip:} be sure to call {\tt event.Skip()} for events that you don't process in
  55 key event function, otherwise menu shortcuts may cease to work under Windows.
  56
  57 \wxheading{Derived from}
  58
  59 \helpref{wxEvent}{wxevent}
  60
  61 \wxheading{Include files}
  62
  63 <wx/event.h>
  64
  65 \wxheading{Event table macros}
  66
  67 To process a key event, use these event handler macros to direct input to member
  68 functions that take a wxKeyEvent argument.
  69
  70 \twocolwidtha{7cm}
  71 \begin{twocollist}\itemsep=0pt
  72 \twocolitem{{\bf EVT\_KEY\_DOWN(func)}}{Process a wxEVT\_KEY\_DOWN event (any key has been pressed).}
  73 \twocolitem{{\bf EVT\_KEY\_UP(func)}}{Process a wxEVT\_KEY\_UP event (any key has been released).}
  74 \twocolitem{{\bf EVT\_CHAR(func)}}{Process a wxEVT\_CHAR event.}
  75 %\twocolitem{{\bf EVT\_CHAR\_HOOK(func)}}{Process a wxEVT\_CHAR\_HOOK event.}
  76 \end{twocollist}%
  77
  78
  79 \latexignore{\rtfignore{\wxheading{Members}}}
  80
  81 \membersection{wxKeyEvent::m\_altDown}
  82
  83 \member{bool}{m\_altDown}
  84
  85 true if the Alt key is pressed down.
  86
  87 \membersection{wxKeyEvent::m\_controlDown}
  88
  89 \member{bool}{m\_controlDown}
  90
  91 true if control is pressed down.
  92
  93 \membersection{wxKeyEvent::m\_keyCode}
  94
  95 \member{long}{m\_keyCode}
  96
  97 Virtual keycode. See \helpref{Keycodes}{keycodes} for a list of identifiers.
  98
  99 \membersection{wxKeyEvent::m\_metaDown}
 100
 101 \member{bool}{m\_metaDown}
 102
 103 true if the Meta key is pressed down.
 104
 105 \membersection{wxKeyEvent::m\_shiftDown}
 106
 107 \member{bool}{m\_shiftDown}
 108
 109 true if shift is pressed down.
 110
 111 \membersection{wxKeyEvent::m\_x}
 112
 113 \member{int}{m\_x}
 114
 115 X position of the event.
 116
 117 \membersection{wxKeyEvent::m\_y}
 118
 119 \member{int}{m\_y}
 120
 121 Y position of the event.
 122
 123 \membersection{wxKeyEvent::wxKeyEvent}
 124
 125 \func{}{wxKeyEvent}{\param{WXTYPE}{ keyEventType}}
 126
 127 Constructor. Currently, the only valid event types are wxEVT\_CHAR and wxEVT\_CHAR\_HOOK.
 128
 129 \membersection{wxKeyEvent::AltDown}
 130
 131 \constfunc{bool}{AltDown}{\void}
 132
 133 Returns true if the Alt key was down at the time of the key event.
 134
 135 \membersection{wxKeyEvent::ControlDown}
 136
 137 \constfunc{bool}{ControlDown}{\void}
 138
 139 Returns true if the control key was down at the time of the key event.
 140
 141 \membersection{wxKeyEvent::GetKeyCode}
 142
 143 \constfunc{int}{GetKeyCode}{\void}
 144
 145 Returns the virtual key code. ASCII events return normal ASCII values,
 146 while non-ASCII events return values such as {\bf WXK\_LEFT} for the
 147 left cursor key. See \helpref{Keycodes}{keycodes} for a full list of the virtual key codes.
 148
 149 \membersection{wxKeyEvent::GetRawKeyCode}
 150
 151 \constfunc{wxUint32}{GetRawKeyCode}{\void}
 152
 153 Returns the raw key code for this event. This is a platform-dependent scan code
 154 which should only be used in advanced applications.
 155
 156 {\bf NB:} Currently the raw key codes are not supported by all ports, use
 157 {\tt\#ifdef wxHAS\_RAW\_KEY\_CODES} to determine if this feature is available.
 158
 159 \membersection{wxKeyEvent::GetRawKeyFlags}
 160
 161 \constfunc{wxUint32}{GetRawKeyFlags}{\void}
 162
 163 Returns the low level key flags for this event. The flags are
 164 platform-dependent and should only be used in advanced applications.
 165
 166 {\bf NB:} Currently the raw key flags are not supported by all ports, use
 167 {\tt \#ifdef wxHAS\_RAW\_KEY\_CODES} to determine if this feature is available.
 168
 169 \membersection{wxKeyEvent::GetX}
 170
 171 \constfunc{long}{GetX}{\void}
 172
 173 Returns the X position (in client coordinates) of the event.
 174
 175 \membersection{wxKeyEvent::GetY}
 176
 177 \constfunc{long}{GetY}{\void}
 178
 179 Returns the Y (in client coordinates) position of the event.
 180
 181 \membersection{wxKeyEvent::MetaDown}
 182
 183 \constfunc{bool}{MetaDown}{\void}
 184
 185 Returns true if the Meta key was down at the time of the key event.
 186
 187 \membersection{wxKeyEvent::GetPosition}
 188
 189 \constfunc{wxPoint}{GetPosition}{\void}
 190
 191 \constfunc{void}{GetPosition}{\param{long *}{x}, \param{long *}{y}}
 192
 193 Obtains the position (in client coordinates) at which the key was pressed.
 194
 195 \membersection{wxKeyEvent::HasModifiers}
 196
 197 \constfunc{bool}{HasModifiers}{\void}
 198
 199 Returns true if either {\sc Ctrl} or {\sc Alt} keys was down
 200 at the time of the key event. Note that this function does not take into
 201 account neither {\sc Shift} nor {\sc Meta} key states (the reason for ignoring
 202 the latter is that it is common for {\sc NumLock} key to be configured as
 203 {\sc Meta} under X but the key presses even while {\sc NumLock} is on should
 204 be still processed normally).
 205
 206 \membersection{wxKeyEvent::ShiftDown}\label{wxkeyeventshiftdown}
 207
 208 \constfunc{bool}{ShiftDown}{\void}
 209
 210 Returns true if the shift key was down at the time of the key event.
 211