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 corresponding
  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 \textbf{Deprecated: } Please use \helpref{GetModifiers}{wxkeyeventgetmodifiers}
  87 instead!
  88
  89 true if the Alt key is pressed down.
  90
  91
  92 \membersection{wxKeyEvent::m\_controlDown}\label{wxkeyeventmcontroldown}
  93
  94 \member{bool}{m\_controlDown}
  95
  96 \textbf{Deprecated: } Please use \helpref{GetModifiers}{wxkeyeventgetmodifiers}
  97 instead!
  98
  99 true if control is pressed down.
 100
 101
 102 \membersection{wxKeyEvent::m\_keyCode}\label{wxkeyeventmkeycode}
 103
 104 \member{long}{m\_keyCode}
 105
 106 \textbf{Deprecated: } Please use \helpref{GetKeyCode}{wxkeyeventgetkeycode}
 107 instead!
 108
 109 Virtual keycode. See \helpref{Keycodes}{keycodes} for a list of identifiers.
 110
 111
 112 \membersection{wxKeyEvent::m\_metaDown}\label{wxkeyeventmmetadown}
 113
 114 \member{bool}{m\_metaDown}
 115
 116 \textbf{Deprecated: } Please use \helpref{GetModifiers}{wxkeyeventgetmodifiers}
 117 instead!
 118
 119 true if the Meta key is pressed down.
 120
 121
 122 \membersection{wxKeyEvent::m\_shiftDown}\label{wxkeyeventmshiftdown}
 123
 124 \member{bool}{m\_shiftDown}
 125
 126 \textbf{Deprecated: } Please use \helpref{GetModifiers}{wxkeyeventgetmodifiers}
 127 instead!
 128
 129 true if shift is pressed down.
 130
 131
 132 \membersection{wxKeyEvent::m\_x}\label{wxkeyeventmx}
 133
 134 \member{int}{m\_x}
 135
 136 \textbf{Deprecated: } Please use \helpref{GetX}{wxkeyeventgetx} instead!
 137
 138 X position of the event.
 139
 140
 141 \membersection{wxKeyEvent::m\_y}\label{wxkeyeventmy}
 142
 143 \member{int}{m\_y}
 144
 145 \textbf{Deprecated: } Please use \helpref{GetY}{wxkeyeventgety} instead!
 146
 147 Y position of the event.
 148
 149
 150 \membersection{wxKeyEvent::wxKeyEvent}\label{wxkeyeventctor}
 151
 152 \func{}{wxKeyEvent}{\param{WXTYPE}{ keyEventType}}
 153
 154 Constructor. Currently, the only valid event types are wxEVT\_CHAR and wxEVT\_CHAR\_HOOK.
 155
 156
 157 \membersection{wxKeyEvent::AltDown}\label{wxkeyeventaltdown}
 158
 159 \constfunc{bool}{AltDown}{\void}
 160
 161 Returns true if the Alt key was down at the time of the key event.
 162
 163 Notice that \helpref{GetModifiers}{wxkeyeventgetmodifiers} is easier to use
 164 correctly than this function so you should consider using it in new code.
 165
 166
 167 \membersection{wxKeyEvent::CmdDown}\label{wxkeyeventcmddown}
 168
 169 \constfunc{bool}{CmdDown}{\void}
 170
 171 \textsc{Cmd} is a pseudo key which is the same as Control for PC and Unix
 172 platforms but the special \textsc{Apple} (a.k.a as \textsc{Command}) key under
 173 Macs: it makes often sense to use it instead of, say, ControlDown() because Cmd
 174 key is used for the same thing under Mac as Ctrl elsewhere (but Ctrl still
 175 exists, just not used for this purpose under Mac). So for non-Mac platforms
 176 this is the same as \helpref{ControlDown()}{wxkeyeventcontroldown} and under
 177 Mac this is the same as \helpref{MetaDown()}{wxkeyeventmetadown}.
 178
 179
 180 \membersection{wxKeyEvent::ControlDown}\label{wxkeyeventcontroldown}
 181
 182 \constfunc{bool}{ControlDown}{\void}
 183
 184 Returns true if the control key was down at the time of the key event.
 185
 186 Notice that \helpref{GetModifiers}{wxkeyeventgetmodifiers} is easier to use
 187 correctly than this function so you should consider using it in new code.
 188
 189
 190 \membersection{wxKeyEvent::GetKeyCode}\label{wxkeyeventgetkeycode}
 191
 192 \constfunc{int}{GetKeyCode}{\void}
 193
 194 Returns the virtual key code. ASCII events return normal ASCII values,
 195 while non-ASCII events return values such as {\bf WXK\_LEFT} for the
 196 left cursor key. See \helpref{Keycodes}{keycodes} for a full list of
 197 the virtual key codes.
 198
 199 Note that in Unicode build, the returned value is meaningful only if the
 200 user entered a character that can be represented in current locale's default
 201 charset. You can obtain the corresponding Unicode character using
 202 \helpref{GetUnicodeKey}{wxkeyeventgetunicodekey}.
 203
 204
 205 \membersection{wxKeyEvent::GetModifiers}\label{wxkeyeventgetmodifiers}
 206
 207 \constfunc{int}{GetModifiers}{\void}
 208
 209 Return the bitmask of modifier keys which were pressed when this event
 210 happened. See \helpref{key modifier constants}{keymodifiers} for the full list
 211 of modifiers.
 212
 213 Notice that this function is easier to use correctly than, for example,
 214 \helpref{ControlDown}{wxkeyeventcontroldown} because when using the latter you
 215 also have to remember to test that none of the other modifiers is pressed:
 216
 217 \begin{verbatim}
 218     if ( ControlDown() && !AltDown() && !ShiftDown() && !MetaDown() )
 219         ... handle Ctrl-XXX ...
 220 \end{verbatim}
 221
 222 and forgetting to do it can result in serious program bugs (e.g. program not
 223 working with European keyboard layout where \textsc{AltGr} key which is seen by
 224 the program as combination of \textsc{Ctrl} and \textsc{Alt} is used). On the
 225 other hand, you can simply write
 226
 227 \begin{verbatim}
 228     if ( GetModifiers() == wxMOD_CONTROL )
 229         ... handle Ctrl-XXX ...
 230 \end{verbatim}
 231
 232 with this function.
 233
 234
 235 \membersection{wxKeyEvent::GetPosition}\label{wxkeyeventgetposition}
 236
 237 \constfunc{wxPoint}{GetPosition}{\void}
 238
 239 \constfunc{void}{GetPosition}{\param{long *}{x}, \param{long *}{y}}
 240
 241 Obtains the position (in client coordinates) at which the key was pressed.
 242
 243
 244 \membersection{wxKeyEvent::GetRawKeyCode}\label{wxkeyeventgetrawkeycode}
 245
 246 \constfunc{wxUint32}{GetRawKeyCode}{\void}
 247
 248 Returns the raw key code for this event. This is a platform-dependent scan code
 249 which should only be used in advanced applications.
 250
 251 {\bf NB:} Currently the raw key codes are not supported by all ports, use
 252 {\tt\#ifdef wxHAS\_RAW\_KEY\_CODES} to determine if this feature is available.
 253
 254
 255 \membersection{wxKeyEvent::GetRawKeyFlags}\label{wxkeyeventgetrawkeyflags}
 256
 257 \constfunc{wxUint32}{GetRawKeyFlags}{\void}
 258
 259 Returns the low level key flags for this event. The flags are
 260 platform-dependent and should only be used in advanced applications.
 261
 262 {\bf NB:} Currently the raw key flags are not supported by all ports, use
 263 {\tt \#ifdef wxHAS\_RAW\_KEY\_CODES} to determine if this feature is available.
 264
 265
 266 \membersection{wxKeyEvent::GetUnicodeKey}\label{wxkeyeventgetunicodekey}
 267
 268 \constfunc{wxChar}{GetUnicodeKey}{\void}
 269
 270 Returns the Unicode character corresponding to this key event.
 271
 272 This function is only available in Unicode build, i.e. when
 273 \texttt{wxUSE\_UNICODE} is $1$.
 274
 275
 276 \membersection{wxKeyEvent::GetX}\label{wxkeyeventgetx}
 277
 278 \constfunc{long}{GetX}{\void}
 279
 280 Returns the X position (in client coordinates) of the event.
 281
 282
 283 \membersection{wxKeyEvent::GetY}\label{wxkeyeventgety}
 284
 285 \constfunc{long}{GetY}{\void}
 286
 287 Returns the Y (in client coordinates) position of the event.
 288
 289
 290 \membersection{wxKeyEvent::HasModifiers}\label{wxkeyeventhasmodifiers}
 291
 292 \constfunc{bool}{HasModifiers}{\void}
 293
 294 Returns true if either {\sc Ctrl} or {\sc Alt} keys was down
 295 at the time of the key event. Note that this function does not take into
 296 account neither {\sc Shift} nor {\sc Meta} key states (the reason for ignoring
 297 the latter is that it is common for {\sc NumLock} key to be configured as
 298 {\sc Meta} under X but the key presses even while {\sc NumLock} is on should
 299 be still processed normally).
 300
 301
 302 \membersection{wxKeyEvent::MetaDown}\label{wxkeyeventmetadown}
 303
 304 \constfunc{bool}{MetaDown}{\void}
 305
 306 Returns true if the Meta key was down at the time of the key event.
 307
 308 Notice that \helpref{GetModifiers}{wxkeyeventgetmodifiers} is easier to use
 309 correctly than this function so you should consider using it in new code.
 310
 311
 312 \membersection{wxKeyEvent::ShiftDown}\label{wxkeyeventshiftdown}
 313
 314 \constfunc{bool}{ShiftDown}{\void}
 315
 316 Returns true if the shift key was down at the time of the key event.
 317
 318 Notice that \helpref{GetModifiers}{wxkeyeventgetmodifiers} is easier to use
 319 correctly than this function so you should consider using it in new code.
 320