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
  82 \membersection{wxKeyEvent::m\_altDown}\label{wxkeyeventmaltdown}
  83
  84 \member{bool}{m\_altDown}
  85
  86 true if the Alt key is pressed down.
  87
  88
  89 \membersection{wxKeyEvent::m\_controlDown}\label{wxkeyeventmcontroldown}
  90
  91 \member{bool}{m\_controlDown}
  92
  93 true if control is pressed down.
  94
  95
  96 \membersection{wxKeyEvent::m\_keyCode}\label{wxkeyeventmkeycode}
  97
  98 \member{long}{m\_keyCode}
  99
 100 Virtual keycode. See \helpref{Keycodes}{keycodes} for a list of identifiers.
 101
 102
 103 \membersection{wxKeyEvent::m\_metaDown}\label{wxkeyeventmmetadown}
 104
 105 \member{bool}{m\_metaDown}
 106
 107 true if the Meta key is pressed down.
 108
 109
 110 \membersection{wxKeyEvent::m\_shiftDown}\label{wxkeyeventmshiftdown}
 111
 112 \member{bool}{m\_shiftDown}
 113
 114 true if shift is pressed down.
 115
 116
 117 \membersection{wxKeyEvent::m\_x}\label{wxkeyeventmx}
 118
 119 \member{int}{m\_x}
 120
 121 X position of the event.
 122
 123
 124 \membersection{wxKeyEvent::m\_y}\label{wxkeyeventmy}
 125
 126 \member{int}{m\_y}
 127
 128 Y position of the event.
 129
 130
 131 \membersection{wxKeyEvent::wxKeyEvent}\label{wxkeyeventctor}
 132
 133 \func{}{wxKeyEvent}{\param{WXTYPE}{ keyEventType}}
 134
 135 Constructor. Currently, the only valid event types are wxEVT\_CHAR and wxEVT\_CHAR\_HOOK.
 136
 137
 138 \membersection{wxKeyEvent::AltDown}\label{wxkeyeventaltdown}
 139
 140 \constfunc{bool}{AltDown}{\void}
 141
 142 Returns true if the Alt key was down at the time of the key event.
 143
 144
 145 \membersection{wxKeyEvent::CmdDown}\label{wxkeyeventcmddown}
 146
 147 \constfunc{bool}{CmdDown}{\void}
 148
 149 "Cmd" is a pseudo key which is the same as Control for PC and Unix platforms
 150 but the special "Apple" (a.k.a as "Command") key under Macs: it makes often
 151 sense to use it instead of, say, ControlDown() because Cmd key is used for the
 152 same thing under Mac as Ctrl elsewhere (but Ctrl still exists, just not used
 153 for this purpose under Mac). So for non-Mac platforms this is the same as
 154 \helpref{ControlDown()}{wxkeyeventcontroldown} and under Mac this is the same
 155 as \helpref{MetaDown()}{wxkeyeventmetadown}.
 156
 157
 158 \membersection{wxKeyEvent::ControlDown}\label{wxkeyeventcontroldown}
 159
 160 \constfunc{bool}{ControlDown}{\void}
 161
 162 Returns true if the control key was down at the time of the key event.
 163
 164
 165 \membersection{wxKeyEvent::GetKeyCode}\label{wxkeyeventgetkeycode}
 166
 167 \constfunc{int}{GetKeyCode}{\void}
 168
 169 Returns the virtual key code. ASCII events return normal ASCII values,
 170 while non-ASCII events return values such as {\bf WXK\_LEFT} for the
 171 left cursor key. See \helpref{Keycodes}{keycodes} for a full list of
 172 the virtual key codes.
 173
 174 Note that in Unicode build, the returned value is meaningful only if the
 175 user entered a character that can be represented in current locale's default
 176 charset. You can obtain the corresponding Unicode character using
 177 \helpref{GetUnicodeKey}{wxkeyeventgetunicodekey}.
 178
 179
 180 \membersection{wxKeyEvent::GetPosition}\label{wxkeyeventgetposition}
 181
 182 \constfunc{wxPoint}{GetPosition}{\void}
 183
 184 \constfunc{void}{GetPosition}{\param{long *}{x}, \param{long *}{y}}
 185
 186 Obtains the position (in client coordinates) at which the key was pressed.
 187
 188
 189 \membersection{wxKeyEvent::GetRawKeyCode}\label{wxkeyeventgetrawkeycode}
 190
 191 \constfunc{wxUint32}{GetRawKeyCode}{\void}
 192
 193 Returns the raw key code for this event. This is a platform-dependent scan code
 194 which should only be used in advanced applications.
 195
 196 {\bf NB:} Currently the raw key codes are not supported by all ports, use
 197 {\tt\#ifdef wxHAS\_RAW\_KEY\_CODES} to determine if this feature is available.
 198
 199
 200 \membersection{wxKeyEvent::GetRawKeyFlags}\label{wxkeyeventgetrawkeyflags}
 201
 202 \constfunc{wxUint32}{GetRawKeyFlags}{\void}
 203
 204 Returns the low level key flags for this event. The flags are
 205 platform-dependent and should only be used in advanced applications.
 206
 207 {\bf NB:} Currently the raw key flags are not supported by all ports, use
 208 {\tt \#ifdef wxHAS\_RAW\_KEY\_CODES} to determine if this feature is available.
 209
 210
 211 \membersection{wxKeyEvent::GetUnicodeKey}\label{wxkeyeventgetunicodekey}
 212
 213 \constfunc{wxChar}{GetUnicodeKey}{\void}
 214
 215 Returns the Unicode character corresponding to this key event.
 216
 217 This function is only available in Unicode build, i.e. when
 218 \texttt{wxUSE\_UNICODE} is $1$.
 219
 220
 221 \membersection{wxKeyEvent::GetX}\label{wxkeyeventgetx}
 222
 223 \constfunc{long}{GetX}{\void}
 224
 225 Returns the X position (in client coordinates) of the event.
 226
 227
 228 \membersection{wxKeyEvent::GetY}\label{wxkeyeventgety}
 229
 230 \constfunc{long}{GetY}{\void}
 231
 232 Returns the Y (in client coordinates) position of the event.
 233
 234
 235 \membersection{wxKeyEvent::HasModifiers}\label{wxkeyeventhasmodifiers}
 236
 237 \constfunc{bool}{HasModifiers}{\void}
 238
 239 Returns true if either {\sc Ctrl} or {\sc Alt} keys was down
 240 at the time of the key event. Note that this function does not take into
 241 account neither {\sc Shift} nor {\sc Meta} key states (the reason for ignoring
 242 the latter is that it is common for {\sc NumLock} key to be configured as
 243 {\sc Meta} under X but the key presses even while {\sc NumLock} is on should
 244 be still processed normally).
 245
 246
 247 \membersection{wxKeyEvent::MetaDown}\label{wxkeyeventmetadown}
 248
 249 \constfunc{bool}{MetaDown}{\void}
 250
 251 Returns true if the Meta key was down at the time of the key event.
 252
 253
 254 \membersection{wxKeyEvent::ShiftDown}\label{wxkeyeventshiftdown}
 255
 256 \constfunc{bool}{ShiftDown}{\void}
 257
 258 Returns true if the shift key was down at the time of the key event.
 259