qwhatsthis.3qt

Trolltech公司发布的基于C++图形开发环境

'\" t
.TH QWhatsThis 3qt "24 January 2005" "Trolltech AS" \" -*- nroff -*-
.\" Copyright 1992-2001 Trolltech AS.  All rights reserved.  See the
.\" license file included in the distribution for a complete license
.\" statement.
.\"
.ad l
.nh
.SH NAME
QWhatsThis \- Simple description of any widget, e.g. answering the question "what's this?"
.br
.PP
\fC#include <qwhatsthis.h>\fR
.PP
Inherits Qt.
.PP
.SS "Public Members"
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.BI "\fBQWhatsThis\fR ( QWidget * ) "
.br
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.BI "virtual \fB~QWhatsThis\fR () "
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.BI "virtual QString \fBtext\fR ( const QPoint & ) "
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.SS "Static Public Members"
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.BI "void \fBadd\fR ( QWidget *, const QString & ) "
.br
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.BI "void \fBremove\fR ( QWidget * ) "
.br
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.BI "QString \fBtextFor\fR ( QWidget *, const QPoint & pos = QPoint ()) "
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.BI "QToolButton* \fBwhatsThisButton\fR ( QWidget * parent ) "
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.BI "void \fBenterWhatsThisMode\fR () "
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.BI "bool \fBinWhatsThisMode\fR () "
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.BI "void \fBleaveWhatsThisMode\fR ( const QString & = QString::null, const QPoint & pos = QCursor::pos ()) "
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.SH DESCRIPTION
The QWhatsThis class provides a simple description of any widget, e.g. answering the question "what's this?"
.PP
\fIWhat's This\fR help is part of an application's online help systems, offering users a level of detail between tool tips and full text browsing windows.
.PP
QWhatsThis provides a single window with a single explanatory text, which pops up quickly when the user asks "what's this?", and goes away as soon as the user does something else.
.PP
To assign \fIWhat's This?\fR text to a widget, you simply call QWhatsThis::add() for the widget. To assign text to a menu item, call QMenuData::setWhatsThis(), and for a global accelerator key, call QAccel::setWhatsThis().
.PP
The text can be either rich text or plain text. If you specify a rich text formatted string, it will be rendered using the default stylesheet. This makes it also possible to embed images. See QStyleSheet::defaultSheet() for details.
.PP
By default, the user will be able to view the text for a widget by pressing Shift-F1 while the widget has focus. On window systems where a context help button is provided in the window decorations, that button enters \fIWhat's This?\fR mode. In this mode, if the user clicks on a widget, help will be given for the widget. The mode is left when help is given or when the user presses the Escape key.
.PP
An alternative way to enter \fIWhat's This?\fR mode is to use the ready-made toolbar tool button from QWhatsThis::whatsThisButton(). If you are using QMainWindow, you can also use the QMainWindow::whatsThis() slot to invoke the mode from a menu item.
.PP
.ce 1
.B "[Image Omitted]"
.PP
For more control, you can create a dedicated QWhatsThis object for a special widget. By subclassing and reimplementing QWhatsThis::text() it is possible to have different explanatory texts depending on the position of the mouse click.
.PP
If your widget needs even more control, see QWidget::customWhatsThis().
.PP
To remove added text, you can use QWhatsThis::remove(), but since the text is automatically removed when the widget is destroyed, this is rarely needed.
.PP
See also QToolTip.
.SH MEMBER FUNCTION DOCUMENTATION
.SH "QWhatsThis::QWhatsThis ( QWidget * widget )"
Constructs a dynamic \fIWhat's This\fR object for \fIwidget.\fR
.PP
When the widget is queried by the user, the text() function of this QWhatsThis will be called to provide the appropriate text, rather than using text assigned by add().
.SH "QWhatsThis::~QWhatsThis () \fC[virtual]\fR"
Destructs the object and frees any allocated resources.
.SH "void QWhatsThis::add ( QWidget * widget, const QString & text ) \fC[static]\fR"
Adds \fItext\fR as \fIWhat's This\fR help for \fIwidget.\fR If the text is rich text formatted (ie. it contains markup), it will be rendered with the default stylesheet QStyleSheet::defaultSheet().
.PP
The text is destroyed if the widget is later destroyed and so need not be explicitly removed.
.PP
See also remove().
.SH "void QWhatsThis::enterWhatsThisMode () \fC[static]\fR"
Enters \fIWhat's This\fR? mode and returns immediately.
.PP
Qt will install a special cursor and take over mouse input until the user clicks somewhere, then show any help available and switch out of \fIWhat's This\fR mode. Finally, Qt removes the special cursor and help window then restores ordinary event processing, at which point the left mouse button is not pressed.
.PP
The user can also use the Escape key to leave \fIWhat's This\fR? mode.
.PP
See also inWhatsThisMode() and leaveWhatsThisMode().
.SH "bool QWhatsThis::inWhatsThisMode () \fC[static]\fR"
Returns whether the application is in \fIWhat's This\fR mode.
.PP
See also enterWhatsThisMode() and leaveWhatsThisMode().
.SH "void QWhatsThis::leaveWhatsThisMode ( const QString & text = QString::null, const QPoint & pos = QCursor::pos ()) \fC[static]\fR"
Leaves \fIWhat's This\fR? question mode
.PP
This function is used internally by widgets that support QWidget::customWhatsThis(), applications do not usually call it. An example for such a kind of widget is QPopupMenu: Menus still work normally in \fIWhat's This\fR mode, but provide help texts for single menu items instead.
.PP
If \fItext\fR is not a null string, then a \fIWhat's This\fR help window is displayed at the global screen position \fIpos.\fR
.PP
See also inWhatsThisMode() and enterWhatsThisMode().
.SH "void QWhatsThis::remove ( QWidget * widget ) \fC[static]\fR"
Removes the \fIWhat's This\fR help for \fIwidget.\fR This happens automatically if the widget is destroyed.
.PP
See also add().
.SH "QString QWhatsThis::text ( const QPoint & ) \fC[virtual]\fR"
This virtual functions returns the text for position \fIp\fR in the widget that this \fIWhat's This\fR object documents. If there is no \fIWhat's This\fR text for a position, QString::null is returned.
.PP
The default implementation returns QString::null.
.SH "QString QWhatsThis::textFor ( QWidget * widget, const QPoint & pos = QPoint ()) \fC[static]\fR"
Returns the text for \fIwidget,\fR or a null string if there is no \fIWhat's This\fR help for \fIwidget.\fR
.PP
See also add().
.SH "QToolButton * QWhatsThis::whatsThisButton ( QWidget * parent ) \fC[static]\fR"
Creates a QToolButton pre-configured to enter \fIWhat's This\fR mode when clicked. You will often use this with a toolbar:
.PP
.nf
.br
     (void)QWhatsThis::whatsThisButton( my_help_tool_bar );
.fi
.SH "SEE ALSO"
.BR http://doc.trolltech.com/qwhatsthis.html
.BR http://www.trolltech.com/faq/tech.html
.SH COPYRIGHT
Copyright 1992-2001 Trolltech AS, http://www.trolltech.com.  See the
license file included in the distribution for a complete license
statement.
.SH AUTHOR
Generated automatically from the source code.
.SH BUGS
If you find a bug in Qt, please report it as described in
.BR http://doc.trolltech.com/bughowto.html .
Good bug reports make our job much simpler. Thank you.
.P
In case of content or formattting problems with this manual page, please
report them to
.BR [e-mail] .
Please include the name of the manual page (qwhatsthis.3qt) and the Qt
version (2.3.10).