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