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 \helpref{wxObject}{wxobject}
  61
  62 \wxheading{Include files}
  63
  64 <wx/event.h>
  65
  66 \wxheading{Library}
  67
  68 \helpref{wxCore}{librarieslist}
  69
  70 \wxheading{Event table macros}
  71
  72 To process a key event, use these event handler macros to direct input to member
  73 functions that take a wxKeyEvent argument.
  74
  75 \twocolwidtha{7cm}
  76 \begin{twocollist}\itemsep=0pt
  77 \twocolitem{{\bf EVT\_KEY\_DOWN(func)}}{Process a wxEVT\_KEY\_DOWN event (any key has been pressed).}
  78 \twocolitem{{\bf EVT\_KEY\_UP(func)}}{Process a wxEVT\_KEY\_UP event (any key has been released).}
  79 \twocolitem{{\bf EVT\_CHAR(func)}}{Process a wxEVT\_CHAR event.}
  80 %\twocolitem{{\bf EVT\_CHAR\_HOOK(func)}}{Process a wxEVT\_CHAR\_HOOK event.}
  81 \end{twocollist}%
  82
  83
  84 \latexignore{\rtfignore{\wxheading{Members}}}
  85
  86
  87 \membersection{wxKeyEvent::m\_altDown}\label{wxkeyeventmaltdown}
  88
  89 \member{bool}{m\_altDown}
  90
  91 \textbf{Deprecated: } Please use \helpref{GetModifiers}{wxkeyeventgetmodifiers}
  92 instead!
  93
  94 true if the Alt key is pressed down.
  95
  96
  97 \membersection{wxKeyEvent::m\_controlDown}\label{wxkeyeventmcontroldown}
  98
  99 \member{bool}{m\_controlDown}
 100
 101 \textbf{Deprecated: } Please use \helpref{GetModifiers}{wxkeyeventgetmodifiers}
 102 instead!
 103
 104 true if control is pressed down.
 105
 106
 107 \membersection{wxKeyEvent::m\_keyCode}\label{wxkeyeventmkeycode}
 108
 109 \member{long}{m\_keyCode}
 110
 111 \textbf{Deprecated: } Please use \helpref{GetKeyCode}{wxkeyeventgetkeycode}
 112 instead!
 113
 114 Virtual keycode. See \helpref{Keycodes}{keycodes} for a list of identifiers.
 115
 116
 117 \membersection{wxKeyEvent::m\_metaDown}\label{wxkeyeventmmetadown}
 118
 119 \member{bool}{m\_metaDown}
 120
 121 \textbf{Deprecated: } Please use \helpref{GetModifiers}{wxkeyeventgetmodifiers}
 122 instead!
 123
 124 true if the Meta key is pressed down.
 125
 126
 127 \membersection{wxKeyEvent::m\_shiftDown}\label{wxkeyeventmshiftdown}
 128
 129 \member{bool}{m\_shiftDown}
 130
 131 \textbf{Deprecated: } Please use \helpref{GetModifiers}{wxkeyeventgetmodifiers}
 132 instead!
 133
 134 true if shift is pressed down.
 135
 136
 137 \membersection{wxKeyEvent::m\_x}\label{wxkeyeventmx}
 138
 139 \member{int}{m\_x}
 140
 141 \textbf{Deprecated: } Please use \helpref{GetX}{wxkeyeventgetx} instead!
 142
 143 X position of the event.
 144
 145
 146 \membersection{wxKeyEvent::m\_y}\label{wxkeyeventmy}
 147
 148 \member{int}{m\_y}
 149
 150 \textbf{Deprecated: } Please use \helpref{GetY}{wxkeyeventgety} instead!
 151
 152 Y position of the event.
 153
 154
 155 \membersection{wxKeyEvent::wxKeyEvent}\label{wxkeyeventctor}
 156
 157 \func{}{wxKeyEvent}{\param{WXTYPE}{ keyEventType}}
 158
 159 Constructor. Currently, the only valid event types are wxEVT\_CHAR and wxEVT\_CHAR\_HOOK.
 160
 161
 162 \membersection{wxKeyEvent::AltDown}\label{wxkeyeventaltdown}
 163
 164 \constfunc{bool}{AltDown}{\void}
 165
 166 Returns true if the Alt key was down at the time of the key event.
 167
 168 Notice that \helpref{GetModifiers}{wxkeyeventgetmodifiers} is easier to use
 169 correctly than this function so you should consider using it in new code.
 170
 171
 172 \membersection{wxKeyEvent::CmdDown}\label{wxkeyeventcmddown}
 173
 174 \constfunc{bool}{CmdDown}{\void}
 175
 176 \textsc{Cmd} is a pseudo key which is the same as Control for PC and Unix
 177 platforms but the special \textsc{Apple} (a.k.a as \textsc{Command}) key under
 178 Macs: it makes often sense to use it instead of, say, ControlDown() because Cmd
 179 key is used for the same thing under Mac as Ctrl elsewhere (but Ctrl still
 180 exists, just not used for this purpose under Mac). So for non-Mac platforms
 181 this is the same as \helpref{ControlDown()}{wxkeyeventcontroldown} and under
 182 Mac this is the same as \helpref{MetaDown()}{wxkeyeventmetadown}.
 183
 184
 185 \membersection{wxKeyEvent::ControlDown}\label{wxkeyeventcontroldown}
 186
 187 \constfunc{bool}{ControlDown}{\void}
 188
 189 Returns true if the control key was down at the time of the key event.
 190
 191 Notice that \helpref{GetModifiers}{wxkeyeventgetmodifiers} is easier to use
 192 correctly than this function so you should consider using it in new code.
 193
 194
 195 \membersection{wxKeyEvent::GetKeyCode}\label{wxkeyeventgetkeycode}
 196
 197 \constfunc{int}{GetKeyCode}{\void}
 198
 199 Returns the virtual key code. ASCII events return normal ASCII values,
 200 while non-ASCII events return values such as {\bf WXK\_LEFT} for the
 201 left cursor key. See \helpref{Keycodes}{keycodes} for a full list of
 202 the virtual key codes.
 203
 204 Note that in Unicode build, the returned value is meaningful only if the
 205 user entered a character that can be represented in current locale's default
 206 charset. You can obtain the corresponding Unicode character using
 207 \helpref{GetUnicodeKey}{wxkeyeventgetunicodekey}.
 208
 209
 210 \membersection{wxKeyEvent::GetModifiers}\label{wxkeyeventgetmodifiers}
 211
 212 \constfunc{int}{GetModifiers}{\void}
 213
 214 Return the bitmask of modifier keys which were pressed when this event
 215 happened. See \helpref{key modifier constants}{keymodifiers} for the full list
 216 of modifiers.
 217
 218 Notice that this function is easier to use correctly than, for example,
 219 \helpref{ControlDown}{wxkeyeventcontroldown} because when using the latter you
 220 also have to remember to test that none of the other modifiers is pressed:
 221
 222 \begin{verbatim}
 223     if ( ControlDown() && !AltDown() && !ShiftDown() && !MetaDown() )
 224         ... handle Ctrl-XXX ...
 225 \end{verbatim}
 226
 227 and forgetting to do it can result in serious program bugs (e.g. program not
 228 working with European keyboard layout where \textsc{AltGr} key which is seen by
 229 the program as combination of \textsc{Ctrl} and \textsc{Alt} is used). On the
 230 other hand, you can simply write
 231
 232 \begin{verbatim}
 233     if ( GetModifiers() == wxMOD_CONTROL )
 234         ... handle Ctrl-XXX ...
 235 \end{verbatim}
 236
 237 with this function.
 238
 239
 240 \membersection{wxKeyEvent::GetPosition}\label{wxkeyeventgetposition}
 241
 242 \constfunc{wxPoint}{GetPosition}{\void}
 243
 244 \constfunc{void}{GetPosition}{\param{long *}{x}, \param{long *}{y}}
 245
 246 Obtains the position (in client coordinates) at which the key was pressed.
 247
 248
 249 \membersection{wxKeyEvent::GetRawKeyCode}\label{wxkeyeventgetrawkeycode}
 250
 251 \constfunc{wxUint32}{GetRawKeyCode}{\void}
 252
 253 Returns the raw key code for this event. This is a platform-dependent scan code
 254 which should only be used in advanced applications.
 255
 256 {\bf NB:} Currently the raw key codes are not supported by all ports, use
 257 {\tt\#ifdef wxHAS\_RAW\_KEY\_CODES} to determine if this feature is available.
 258
 259
 260 \membersection{wxKeyEvent::GetRawKeyFlags}\label{wxkeyeventgetrawkeyflags}
 261
 262 \constfunc{wxUint32}{GetRawKeyFlags}{\void}
 263
 264 Returns the low level key flags for this event. The flags are
 265 platform-dependent and should only be used in advanced applications.
 266
 267 {\bf NB:} Currently the raw key flags are not supported by all ports, use
 268 {\tt \#ifdef wxHAS\_RAW\_KEY\_CODES} to determine if this feature is available.
 269
 270
 271 \membersection{wxKeyEvent::GetUnicodeKey}\label{wxkeyeventgetunicodekey}
 272
 273 \constfunc{wxChar}{GetUnicodeKey}{\void}
 274
 275 Returns the Unicode character corresponding to this key event.
 276
 277 This function is only available in Unicode build, i.e. when
 278 \texttt{wxUSE\_UNICODE} is $1$.
 279
 280
 281 \membersection{wxKeyEvent::GetX}\label{wxkeyeventgetx}
 282
 283 \constfunc{long}{GetX}{\void}
 284
 285 Returns the X position (in client coordinates) of the event.
 286
 287
 288 \membersection{wxKeyEvent::GetY}\label{wxkeyeventgety}
 289
 290 \constfunc{long}{GetY}{\void}
 291
 292 Returns the Y (in client coordinates) position of the event.
 293
 294
 295 \membersection{wxKeyEvent::HasModifiers}\label{wxkeyeventhasmodifiers}
 296
 297 \constfunc{bool}{HasModifiers}{\void}
 298
 299 Returns true if either {\sc Ctrl} or {\sc Alt} keys was down
 300 at the time of the key event. Note that this function does not take into
 301 account neither {\sc Shift} nor {\sc Meta} key states (the reason for ignoring
 302 the latter is that it is common for {\sc NumLock} key to be configured as
 303 {\sc Meta} under X but the key presses even while {\sc NumLock} is on should
 304 be still processed normally).
 305
 306
 307 \membersection{wxKeyEvent::MetaDown}\label{wxkeyeventmetadown}
 308
 309 \constfunc{bool}{MetaDown}{\void}
 310
 311 Returns true if the Meta key was down at the time of the key event.
 312
 313 Notice that \helpref{GetModifiers}{wxkeyeventgetmodifiers} is easier to use
 314 correctly than this function so you should consider using it in new code.
 315
 316
 317 \membersection{wxKeyEvent::ShiftDown}\label{wxkeyeventshiftdown}
 318
 319 \constfunc{bool}{ShiftDown}{\void}
 320
 321 Returns true if the shift key was down at the time of the key event.
 322
 323 Notice that \helpref{GetModifiers}{wxkeyeventgetmodifiers} is easier to use
 324 correctly than this function so you should consider using it in new code.
 325