fix technical accuracy of statement

[wxWidgets.git] / docs / latex / wx / mouseevt.tex

\section{\class{wxMouseEvent}}\label{wxmouseevent}

This event class contains information about the events generated by the mouse:
they include mouse buttons press and release events and mouse move events.

All mouse events involving the buttons use {\tt wxMOUSE\_BTN\_LEFT} for the
left mouse button, {\tt wxMOUSE\_BTN\_MIDDLE} for the middle one and
{\tt wxMOUSE\_BTN\_RIGHT} for the right one. Note that not all mice have a
middle button so a portable application should avoid relying on the events from
it.

{\bf NB:} Note that under Windows mouse enter and leave events are not natively supported
by the system but are generated by wxWidgets itself. This has several
drawbacks: the LEAVE\_WINDOW event might be received some time after the mouse
left the window and the state variables for it may have changed during this
time.

{\bf NB:} Note the difference between methods like
\helpref{LeftDown}{wxmouseeventleftdown} and
\helpref{LeftIsDown}{wxmouseeventleftisdown}: the former returns {\tt true}
when the event corresponds to the left mouse button click while the latter
returns {\tt true} if the left mouse button is currently being pressed. For
example, when the user is dragging the mouse you can use
\helpref{LeftIsDown}{wxmouseeventleftisdown} to test
whether the left mouse button is (still) depressed. Also, by convention, if
\helpref{LeftDown}{wxmouseeventleftdown} returns {\tt true},
\helpref{LeftIsDown}{wxmouseeventleftisdown} will also return {\tt true} in
wxWidgets whatever the underlying GUI behaviour is (which is
platform-dependent). The same applies, of course, to other mouse buttons as
well.

\wxheading{Derived from}

\helpref{wxEvent}{wxevent}

\wxheading{Include files}

<wx/event.h>

\wxheading{Event table macros}

To process a mouse event, use these event handler macros to direct input to member
functions that take a wxMouseEvent argument.

\twocolwidtha{7cm}
\begin{twocollist}\itemsep=0pt
\twocolitem{{\bf EVT\_LEFT\_DOWN(func)}}{Process a wxEVT\_LEFT\_DOWN event. The
handler of this event should normally call \helpref{event.Skip()}{wxeventskip} to
allow the default processing to take place as otherwise the window under mouse
wouldn't get the focus.}
\twocolitem{{\bf EVT\_LEFT\_UP(func)}}{Process a wxEVT\_LEFT\_UP event.}
\twocolitem{{\bf EVT\_LEFT\_DCLICK(func)}}{Process a wxEVT\_LEFT\_DCLICK event.}
\twocolitem{{\bf EVT\_MIDDLE\_DOWN(func)}}{Process a wxEVT\_MIDDLE\_DOWN event.}
\twocolitem{{\bf EVT\_MIDDLE\_UP(func)}}{Process a wxEVT\_MIDDLE\_UP event.}
\twocolitem{{\bf EVT\_MIDDLE\_DCLICK(func)}}{Process a wxEVT\_MIDDLE\_DCLICK event.}
\twocolitem{{\bf EVT\_RIGHT\_DOWN(func)}}{Process a wxEVT\_RIGHT\_DOWN event.}
\twocolitem{{\bf EVT\_RIGHT\_UP(func)}}{Process a wxEVT\_RIGHT\_UP event.}
\twocolitem{{\bf EVT\_RIGHT\_DCLICK(func)}}{Process a wxEVT\_RIGHT\_DCLICK event.}
\twocolitem{{\bf EVT\_MOTION(func)}}{Process a wxEVT\_MOTION event.}
\twocolitem{{\bf EVT\_ENTER\_WINDOW(func)}}{Process a wxEVT\_ENTER\_WINDOW event.}
\twocolitem{{\bf EVT\_LEAVE\_WINDOW(func)}}{Process a wxEVT\_LEAVE\_WINDOW event.}
\twocolitem{{\bf EVT\_MOUSEWHEEL(func)}}{Process a wxEVT\_MOUSEWHEEL event.}
\twocolitem{{\bf EVT\_MOUSE\_EVENTS(func)}}{Process all mouse events.}
\end{twocollist}%

\latexignore{\rtfignore{\wxheading{Members}}}


\membersection{wxMouseEvent::m\_altDown}\label{wxmouseeventmaltdown}

\member{bool}{m\_altDown}

true if the Alt key is pressed down.


\membersection{wxMouseEvent::m\_controlDown}\label{wxmouseeventmcontroldown}

\member{bool}{m\_controlDown}

true if control key is pressed down.


\membersection{wxMouseEvent::m\_leftDown}\label{wxmouseeventmleftdown}

\member{bool}{m\_leftDown}

true if the left mouse button is currently pressed down.


\membersection{wxMouseEvent::m\_middleDown}\label{wxmouseeventmmiddledown}

\member{bool}{m\_middleDown}

true if the middle mouse button is currently pressed down.


\membersection{wxMouseEvent::m\_rightDown}\label{wxmouseeventmrightdown}

\member{bool}{m\_rightDown}

true if the right mouse button is currently pressed down.


\membersection{wxMouseEvent::m\_metaDown}\label{wxmouseeventmmetadown}

\member{bool}{m\_metaDown}

true if the Meta key is pressed down.


\membersection{wxMouseEvent::m\_shiftDown}\label{wxmouseeventmshiftdown}

\member{bool}{m\_shiftDown}

true if shift is pressed down.


\membersection{wxMouseEvent::m\_x}\label{wxmouseeventmx}

\member{long}{m\_x}

X-coordinate of the event.


\membersection{wxMouseEvent::m\_y}\label{wxmouseeventmy}

\member{long}{m\_y}

Y-coordinate of the event.


\membersection{wxMouseEvent::m\_wheelRotation}\label{wxmouseeventmwheelrotation}

\member{int}{m\_wheelRotation}

The distance the mouse wheel is rotated.


\membersection{wxMouseEvent::m\_wheelDelta}\label{wxmouseeventmwheeldelta}

\member{int}{m\_wheelDelta}

The wheel delta, normally $120$.


\membersection{wxMouseEvent::m\_linesPerAction}\label{wxmouseeventmlinesperaction}

\member{int}{m\_linesPerAction}

The configured number of lines (or whatever) to be scrolled per wheel
action.



\membersection{wxMouseEvent::wxMouseEvent}\label{wxmouseeventctor}

\func{}{wxMouseEvent}{\param{WXTYPE}{ mouseEventType = 0}, \param{int}{ id = 0}}

Constructor. Valid event types are:

\begin{itemize}
\itemsep=0pt
\item {\bf wxEVT\_ENTER\_WINDOW}
\item {\bf wxEVT\_LEAVE\_WINDOW}
\item {\bf wxEVT\_LEFT\_DOWN}
\item {\bf wxEVT\_LEFT\_UP}
\item {\bf wxEVT\_LEFT\_DCLICK}
\item {\bf wxEVT\_MIDDLE\_DOWN}
\item {\bf wxEVT\_MIDDLE\_UP}
\item {\bf wxEVT\_MIDDLE\_DCLICK}
\item {\bf wxEVT\_RIGHT\_DOWN}
\item {\bf wxEVT\_RIGHT\_UP}
\item {\bf wxEVT\_RIGHT\_DCLICK}
\item {\bf wxEVT\_MOTION}
\item {\bf wxEVT\_MOUSEWHEEL}
\end{itemize}


\membersection{wxMouseEvent::AltDown}\label{wxmouseeventaltdown}

\func{bool}{AltDown}{\void}

Returns true if the Alt key was down at the time of the event.


\membersection{wxMouseEvent::Button}\label{wxmouseeventbutton}

\func{bool}{Button}{\param{int}{ button}}

Returns true if the identified mouse button is changing state. Valid
values of {\it button} are:

\begin{twocollist}\itemsep=0pt
\twocolitem{{\tt wxMOUSE\_BTN\_LEFT}}{check if left button was pressed}
\twocolitem{{\tt wxMOUSE\_BTN\_MIDDLE}}{check if middle button was pressed}
\twocolitem{{\tt wxMOUSE\_BTN\_RIGHT}}{check if right button was pressed}
\twocolitem{{\tt wxMOUSE\_BTN\_ANY}}{check if any button was pressed}
\end{twocollist}


\membersection{wxMouseEvent::ButtonDClick}\label{wxmouseeventbuttondclick}

\func{bool}{ButtonDClick}{\param{int}{ but = wxMOUSE\_BTN\_ANY}}

If the argument is omitted, this returns true if the event was a mouse
double click event. Otherwise the argument specifies which double click event
was generated (see \helpref{Button}{wxmouseeventbutton} for the possible
values).


\membersection{wxMouseEvent::ButtonDown}\label{wxmouseeventbuttondown}

\func{bool}{ButtonDown}{\param{int}{ but = -1}}

If the argument is omitted, this returns true if the event was a mouse
button down event. Otherwise the argument specifies which button-down event
was generated (see \helpref{Button}{wxmouseeventbutton} for the possible
values).



\membersection{wxMouseEvent::ButtonUp}\label{wxmouseeventbuttonup}

\func{bool}{ButtonUp}{\param{int}{ but = -1}}

If the argument is omitted, this returns true if the event was a mouse
button up event. Otherwise the argument specifies which button-up event
was generated (see \helpref{Button}{wxmouseeventbutton} for the possible
values).



\membersection{wxKeyEvent::CmdDown}\label{wxmouseeventcmddown}

\constfunc{bool}{CmdDown}{\void}

Same as \helpref{MetaDown}{wxmouseeventmetadown} under Mac, same as 
\helpref{ControlDown}{wxmouseeventcontroldown} elsewhere.

\wxheading{See also}

\helpref{wxKeyEvent::CmdDown}{wxkeyeventcmddown}


\membersection{wxMouseEvent::ControlDown}\label{wxmouseeventcontroldown}

\func{bool}{ControlDown}{\void}

Returns true if the control key was down at the time of the event.


\membersection{wxMouseEvent::Dragging}\label{wxmouseeventdragging}

\func{bool}{Dragging}{\void}

Returns true if this was a dragging event (motion while a button is depressed).

\wxheading{See also}

\helpref{Moving}{wxmouseeventmoving}


\membersection{wxMouseEvent::Entering}\label{wxmouseevententering}

\func{bool}{Entering}{\void}

Returns true if the mouse was entering the window.

See also \helpref{wxMouseEvent::Leaving}{wxmouseeventleaving}.


\membersection{wxMouseEvent::GetButton}\label{wxmouseeventgetbutton}

\constfunc{int}{GetButton}{\void}

Returns the mouse button which generated this event or {\tt wxMOUSE\_BTN\_NONE} 
if no button is involved (for mouse move, enter or leave event, for example).
Otherwise {\tt wxMOUSE\_BTN\_LEFT} is returned for the left button down, up and
double click events, {\tt wxMOUSE\_BTN\_MIDDLE} and {\tt wxMOUSE\_BTN\_RIGHT} 
for the same events for the middle and the right buttons respectively.


\membersection{wxMouseEvent::GetPosition}\label{wxmouseeventgetposition}

\constfunc{wxPoint}{GetPosition}{\void}

\constfunc{void}{GetPosition}{\param{wxCoord*}{ x}, \param{wxCoord*}{ y}}

\constfunc{void}{GetPosition}{\param{long*}{ x}, \param{long*}{ y}}

Sets *x and *y to the position at which the event occurred.

Returns the physical mouse position in pixels.

Note that if the mouse event has been artificially generated from a special
keyboard combination (e.g. under Windows when the ``menu'' key is pressed), the
returned position is \texttt{wxDefaultPosition}.


\membersection{wxMouseEvent::GetLogicalPosition}\label{wxmouseeventgetlogicalposition}

\constfunc{wxPoint}{GetLogicalPosition}{\param{const wxDC\&}{ dc}}

Returns the logical mouse position in pixels (i.e. translated according to the
translation set for the DC, which usually indicates that the window has been scrolled).



\membersection{wxMouseEvent::GetLinesPerAction}\label{wxmouseeventgetlinesperaction}

\constfunc{int}{GetLinesPerAction}{\void}

Returns the configured number of lines (or whatever) to be scrolled per
wheel action.  Defaults to three.


\membersection{wxMouseEvent::GetWheelRotation}\label{wxmouseeventgetwheelrotation}

\constfunc{int}{GetWheelRotation}{\void}

Get wheel rotation, positive or negative indicates direction of
rotation.  Current devices all send an event when rotation is equal to
+/-WheelDelta, but this allows for finer resolution devices to be
created in the future.  Because of this you shouldn't assume that one
event is equal to 1 line or whatever, but you should be able to either
do partial line scrolling or wait until +/-WheelDelta rotation values
have been accumulated before scrolling.


\membersection{wxMouseEvent::GetWheelDelta}\label{wxmouseeventgetwheeldelta}

\constfunc{int}{GetWheelDelta}{\void}

Get wheel delta, normally $120$.  This is the threshold for action to be
taken, and one such action (for example, scrolling one increment)
should occur for each delta.


\membersection{wxMouseEvent::GetX}\label{wxmouseeventgetx}

\constfunc{long}{GetX}{\void}

Returns X coordinate of the physical mouse event position.


\membersection{wxMouseEvent::GetY}\label{wxmouseeventgety}

\func{long}{GetY}{\void}

Returns Y coordinate of the physical mouse event position.


\membersection{wxMouseEvent::IsButton}\label{wxmouseeventisbutton}

\constfunc{bool}{IsButton}{\void}

Returns true if the event was a mouse button event (not necessarily a button down event -
that may be tested using {\it ButtonDown}).


\membersection{wxMouseEvent::IsPageScroll}\label{wxmouseeventispagescroll}

\constfunc{bool}{IsPageScroll}{\void}

Returns true if the system has been setup to do page scrolling with
the mouse wheel instead of line scrolling.


\membersection{wxMouseEvent::Leaving}\label{wxmouseeventleaving}

\constfunc{bool}{Leaving}{\void}

Returns true if the mouse was leaving the window.

See also \helpref{wxMouseEvent::Entering}{wxmouseevententering}.


\membersection{wxMouseEvent::LeftDClick}\label{wxmouseeventleftdclick}

\constfunc{bool}{LeftDClick}{\void}

Returns true if the event was a left double click.


\membersection{wxMouseEvent::LeftDown}\label{wxmouseeventleftdown}

\constfunc{bool}{LeftDown}{\void}

Returns true if the left mouse button changed to down.


\membersection{wxMouseEvent::LeftIsDown}\label{wxmouseeventleftisdown}

\constfunc{bool}{LeftIsDown}{\void}

Returns true if the left mouse button is currently down, independent
of the current event type.

Please notice that it is {\bf not} the same as
\helpref{LeftDown}{wxmouseeventleftdown} which returns true if the left mouse
button was just pressed. Rather, it describes the state of the mouse button
before the event happened.

This event is usually used in the mouse event handlers which process "move
mouse" messages to determine whether the user is (still) dragging the mouse.


\membersection{wxMouseEvent::LeftUp}\label{wxmouseeventleftup}

\constfunc{bool}{LeftUp}{\void}

Returns true if the left mouse button changed to up.


\membersection{wxMouseEvent::MetaDown}\label{wxmouseeventmetadown}

\constfunc{bool}{MetaDown}{\void}

Returns true if the Meta key was down at the time of the event.


\membersection{wxMouseEvent::MiddleDClick}\label{wxmouseeventmiddledclick}

\constfunc{bool}{MiddleDClick}{\void}

Returns true if the event was a middle double click.


\membersection{wxMouseEvent::MiddleDown}\label{wxmouseeventmiddledown}

\constfunc{bool}{MiddleDown}{\void}

Returns true if the middle mouse button changed to down.


\membersection{wxMouseEvent::MiddleIsDown}\label{wxmouseeventmiddleisdown}

\constfunc{bool}{MiddleIsDown}{\void}

Returns true if the middle mouse button is currently down, independent
of the current event type.


\membersection{wxMouseEvent::MiddleUp}\label{wxmouseeventmiddleup}

\constfunc{bool}{MiddleUp}{\void}

Returns true if the middle mouse button changed to up.


\membersection{wxMouseEvent::Moving}\label{wxmouseeventmoving}

\constfunc{bool}{Moving}{\void}

Returns true if this was a motion event and no mouse buttons were pressed. 
If any mouse button is held pressed, then this method returns \false and 
\helpref{Dragging}{wxmouseeventdragging} returns \true.


\membersection{wxMouseEvent::RightDClick}\label{wxmouseeventrightdclick}

\constfunc{bool}{RightDClick}{\void}

Returns true if the event was a right double click.


\membersection{wxMouseEvent::RightDown}\label{wxmouseeventrightdown}

\constfunc{bool}{RightDown}{\void}

Returns true if the right mouse button changed to down.


\membersection{wxMouseEvent::RightIsDown}\label{wxmouseeventrightisdown}

\constfunc{bool}{RightIsDown}{\void}

Returns true if the right mouse button is currently down, independent
of the current event type.


\membersection{wxMouseEvent::RightUp}\label{wxmouseeventrightup}

\constfunc{bool}{RightUp}{\void}

Returns true if the right mouse button changed to up.


\membersection{wxMouseEvent::ShiftDown}\label{wxmouseeventshiftdown}

\constfunc{bool}{ShiftDown}{\void}

Returns true if the shift key was down at the time of the event.