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