/****************************************************************************** $Id: qt/src/widgets/qscrollbar.cpp   2.3.12   edited 2005-10-27 $**** Implementation of QScrollBar class**** Created : 940427**** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.**** This file is part of the widgets module of the Qt GUI Toolkit.**** This file may be distributed under the terms of the Q Public License** as defined by Trolltech AS of Norway and appearing in the file** LICENSE.QPL included in the packaging of this file.**** This file may be distributed and/or modified under the terms of the** GNU General Public License version 2 as published by the Free Software** Foundation and appearing in the file LICENSE.GPL included in the** packaging of this file.**** Licensees holding valid Qt Enterprise Edition or Qt Professional Edition** licenses may use this file in accordance with the Qt Commercial License** Agreement provided with the Software.**** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.**** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for**   information about Qt Commercial License Agreements.** See http://www.trolltech.com/qpl/ for QPL licensing information.** See http://www.trolltech.com/gpl/ for GPL licensing information.**** Contact info@trolltech.com if any conditions of this licensing are** not clear to you.************************************************************************/#include "qscrollbar.h"#ifndef QT_NO_SCROLLBAR#include "qpainter.h"#include "qbitmap.h"#include "qapplication.h"#include "qtimer.h"#include <limits.h>// REVISED: warwick/*!  \class QScrollBar qscrollbar.h  \brief The QScrollBar widget provides a vertical or horizontal scroll bar.  \ingroup basic  A scroll bar allows the user to control a value within a  program-definable range, and to give the user visible indication of  the current value of a \link QRangeControl range control \endlink.  Scroll bars include four separate controls:  <ul>   <li> The \e line-up and \e line-down controls are little button with    which the user can move one line up or down.  The meaning of "line"    is configurable.  In editors and list boxes it means one line of text,    while an image viewer it might mean 20 pixels.   <li> The \e slider is the handle that indicates the current value    of the scroll bar, and which the user can drag to change the value.    This part of the scroll bar is sometimes called the "thumb".   <li> The \a page-up/down control is the area on which the slider    slides (the scroll bar's background).  Clicking here moves the scroll    bar towards the click.  The meaning of page is also configurable    - in editors and list boxes it means as many lines as there is space    for in the widget.  </ul>  QScrollBar has not much of an API of its own; it mostly relies on  QRangeControl.  The most useful functions are setValue() to set the  scroll bar directly to some value; addPage(), addLine(), subtractPage()  and subtractLine() to simulate the effects of clicking (useful for  accelerator keys; setSteps() to define the values of pageStep() and  lineStep(); and setRange() to set the minValue()  and maxValue() of the scroll bar.  QScrollBar has a convenience  constructor with which you can set most of these properties.  Some GUI styles, for example the provided Windows and Motif styles,  also use the pageStep() value to calculate the size of the slider.  In addition to the access functions from QRangeControl, QScrollBar  has a comprehensive set of signals:  <ul>  <li> valueChanged() - emitted when the scroll bar's value has changed.	  The tracking() determines whether this signal is emitted	    \e during interaction.  <li> sliderPressed() - emitted when the user starts to drag the	  slider  <li> sliderMoved() - emitted when the user drags the slider  <li> sliderReleased() - emitted when the user releases the slider  <li> nextLine() - emitted when the scroll bar has moved one line	  down/rightwards.  Line is defined in QRangeControl.  <li> prevLine() - emitted when the scroll bar has moved one line	  up/leftwards.  <li> nextPage() - emitted when the scroll bar has moved one page	  down/rightwards.  <li> prevPage() - emitted when the scroll bar has moved one page      up/leftwards.  </ul>  QScrollBar only offers integer ranges.  Note that while QScrollBar  handles very large numbers, scroll bars on today's screens cannot  usefully control ranges above about 100,000 pixels.  Beyond that,  it becomes difficult for the user to control the  scroll bar using either keyboard or mouse.  A scroll bar can be controlled by the keyboard, but it has a  default focusPolicy() of \c NoFocus. Use setFocusPolicy() to  enable keyboard focus. See keyPressEvent() for a list of  key bindings.  If you need to add scrollbars to an interface, consider using the  QScrollView class which encapsulates the common uses for scrollbars.  <img src=qscrbar-m.png> <img src=qscrbar-w.png>  \sa QSlider QSpinBox QScrollView  <a href="guibooks.html#fowler">GUI Design Handbook: Scroll Bar</a>*//*!  \fn void QScrollBar::valueChanged( int value )  This signal is emitted when the scroll bar value has changed, with the  new scroll bar value as an argument.*//*!  \fn void QScrollBar::sliderPressed()  This signal is emitted when the user presses the slider with the mouse.*//*!  \fn void QScrollBar::sliderMoved( int value )  This signal is emitted when the slider is moved by the user, with  the new scroll bar value as an argument.  This signal is emitted even when tracking is turned off.  \sa tracking() valueChanged() nextLine() prevLine() nextPage() prevPage()*//*!  \fn void QScrollBar::sliderReleased()  This signal is emitted when the user releases the slider with the mouse.*//*!  \fn void QScrollBar::nextLine()  This signal is emitted when the scroll bar scrolls one line down/right.*//*!  \fn void QScrollBar::prevLine()  This signal is emitted when the scroll bar scrolls one line up/left.*//*!  \fn void QScrollBar::nextPage()  This signal is emitted when the scroll bar scrolls one page down/right.*//*!  \fn void QScrollBar::prevPage()  This signal is emitted when the scroll bar scrolls one page up/left.*/static const int thresholdTime = 500;static const int repeatTime	= 50;#define HORIZONTAL	(orientation() == Horizontal)#define VERTICAL	!HORIZONTAL#define MOTIF_BORDER	2#define SLIDER_MIN	9/*!  Constructs a vertical scroll bar.  The \e parent and \e name arguments are sent to the QWidget constructor.*/QScrollBar::QScrollBar( QWidget *parent, const char *name )    : QWidget( parent, name ){    orient = Vertical;    init();}/*!  Constructs a scroll bar.  The \e orientation must be QScrollBar::Vertical or QScrollBar::Horizontal.  The \e parent and \e name arguments are sent to the QWidget constructor.*/QScrollBar::QScrollBar( Orientation orientation, QWidget *parent,			const char *name )    : QWidget( parent, name ){    orient = orientation;    init();}/*!  Constructs a scroll bar.  \arg \e minValue is the minimum scroll bar value.  \arg \e maxValue is the maximum scroll bar value.  \arg \e lineStep is the line step value.  \arg \e pageStep is the page step value. It is also used to calculate the size	    of the slider.  \arg \e value is the initial value.  \arg \e orientation must be QScrollBar::Vertical or QScrollBar::Horizontal.  The \e parent and \e name arguments are sent to the QWidget constructor.*/QScrollBar::QScrollBar( int minValue, int maxValue, int lineStep, int pageStep,			int value,  Orientation orientation,			QWidget *parent, const char *name )    : QWidget( parent, name ),      QRangeControl( minValue, maxValue, lineStep, pageStep, value ){    orient = orientation;    init();}void QScrollBar::init(){    track = TRUE;    sliderPos = 0;    pressedControl = QStyle::NoScroll;    clickedAt = FALSE;    setFocusPolicy( NoFocus );    repeater = 0;    d = 0;    if ( style() == MotifStyle )	setBackgroundMode( PaletteMid );    else	setBackgroundMode( PaletteBackground );    if ( orient == Horizontal )	setSizePolicy( QSizePolicy( QSizePolicy::Minimum, QSizePolicy::Fixed ) );    else	setSizePolicy( QSizePolicy(  QSizePolicy::Fixed, QSizePolicy::Minimum ) );}/*!  Sets the scroll bar orientation.  The \e orientation must be  QScrollBar::Vertical or QScrollBar::Horizontal.  \sa orientation()*/void QScrollBar::setOrientation( Orientation orientation ){    if ( (uint) orientation == orient )	return;    QSizePolicy pol = sizePolicy();    setSizePolicy( QSizePolicy( pol.verData(), pol.horData() ) );	    orient = orientation;    positionSliderFromValue();    update();}/*!  \fn Orientation QScrollBar::orientation() const  Returns the orientation of the scroll bar; QScrollBar::Vertical or  QScrollBar::Horizontal.  \sa setOrientation()*//*!  \fn void QScrollBar::setTracking( bool enable )  Enables scroll bar tracking if \e enable is TRUE, or disables tracking  if \e enable is FALSE.  If tracking is enabled (the default), the scroll bar emits the  valueChanged() signal while the slider is being dragged.  If  tracking is disabled, the scroll bar emits the valueChanged() signal  only when the user releases the mouse button after moving the  slider.  \sa tracking()*//*!  \fn bool QScrollBar::tracking() const  Returns TRUE if tracking is enabled, or FALSE if tracking is disabled.  Tracking is initially enabled.  \sa setTracking()*//*!  Returns TRUE if the user has clicked the mouse on the slider  and is currently dragging it, or FALSE if not.*/bool QScrollBar::draggingSlider() const{    return pressedControl == QStyle::Slider;}/*!  Reimplements the virtual function QWidget::setPalette().  Sets the background color to the mid color for Motif style scroll bars.*/void QScrollBar::setPalette( const QPalette &p ){    QWidget::setPalette( p );    if ( style() == MotifStyle )	setBackgroundMode( PaletteMid );    else	setBackgroundMode( PaletteBackground );}/*!\reimp*/QSize QScrollBar::sizeHint() const{    constPolish();    QSize sbextent = style().scrollBarExtent();    if ( orient == Horizontal ) {	return QSize( 30, sbextent.height() );    } else {	return QSize( sbextent.width(), 30 );    }}/*!\reimp*/QSizePolicy QScrollBar::sizePolicy() const{    //### removeme 3.0    return QWidget::sizePolicy();}/*!  \internal  Implements the virtual QRangeControl function.*/void QScrollBar::valueChange(){    int tmp = sliderPos;    positionSliderFromValue();    if ( tmp != sliderPos )	drawControls( QStyle::AddPage | QStyle::Slider | QStyle::SubPage,		      pressedControl );    emit valueChanged(value());}/*!  \internal  Implements the virtual QRangeControl function.*/void QScrollBar::stepChange(){    rangeChange();}/*!  \internal  Implements the virtual QRangeControl function.*/void QScrollBar::rangeChange(){    positionSliderFromValue();    drawControls( QStyle::AddLine | QStyle::AddPage | QStyle::Slider |	    QStyle::SubPage | QStyle::SubLine | QStyle::First | QStyle::Last,	    pressedControl );}/*!  Handles timer events for the scroll bar.*/void QScrollBar::doAutoRepeat(){    if ( clickedAt ){	if ( repeater )	    repeater->changeInterval( repeatTime );	action( (QStyle::ScrollControl) pressedControl );	QApplication::syncX();    } else {	stopAutoRepeat();    }}/*! Starts the auto-repeat logic.  Some time after this function iscalled, the auto-repeat starts taking effect, and from then on repeatsuntil stopAutoRepeat() is called.*/void QScrollBar::startAutoRepeat(){    if ( !repeater ) {	repeater = new QTimer( this, "auto-repeat timer" );	connect( repeater, SIGNAL(timeout()),		 this, SLOT(doAutoRepeat()) );    }    repeater->start( thresholdTime, FALSE );}/*! Stops the auto-repeat logic. */void QScrollBar::stopAutoRepeat(){    delete repeater;    repeater = 0;}/*!\reimp*/void QScrollBar::wheelEvent( QWheelEvent *e ){    static float offset = 0;    static QScrollBar* offset_owner = 0;    if (offset_owner != this){	offset_owner = this;	offset = 0;    }    e->accept();    int step = QMIN( QApplication::wheelScrollLines()*lineStep(),		     pageStep() );    if ( e->state() & ControlButton )	step = pageStep();    offset += -e->delta()*step/120;    if (QABS(offset)<1)