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qt3/src/widgets/qrangecontrol.cpp

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/****************************************************************************
**
** Implementation of QRangeControl class
**
** Created : 940427
**
** Copyright (C) 1992-2008 Trolltech ASA. All rights reserved.
**
** This file is part of the widgets module of the Qt GUI Toolkit.
**
** This file may be used under the terms of the GNU General
** Public License versions 2.0 or 3.0 as published by the Free
** Software Foundation and appearing in the files LICENSE.GPL2
** and LICENSE.GPL3 included in the packaging of this file.
** Alternatively you may (at your option) use any later version
** of the GNU General Public License if such license has been
** publicly approved by Trolltech ASA (or its successors, if any)
** and the KDE Free Qt Foundation.
**
** Please review the following information to ensure GNU General
** Public Licensing requirements will be met:
** http://trolltech.com/products/qt/licenses/licensing/opensource/.
** If you are unsure which license is appropriate for your use, please
** review the following information:
** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
** or contact the sales department at sales@trolltech.com.
**
** This file may be used under the terms of the Q Public License as
** defined by Trolltech ASA and appearing in the file LICENSE.QPL
** included in the packaging of this file. Licensees holding valid Qt
** Commercial 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 WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted
** herein.
**
**********************************************************************/
#include "qrangecontrol.h"
#ifndef QT_NO_RANGECONTROL
#include "qglobal.h"
#include <limits.h>
static bool sumOutOfRange(int current, int add);
/*!
\class QRangeControl qrangecontrol.h
\brief The QRangeControl class provides an integer value within a range.
\ingroup misc
Although originally designed for the QScrollBar widget, the
QRangeControl can also be used in conjunction with other widgets
such as QSlider and QSpinBox. Here are the five main concepts in
the class:
\list 1
\i \e{Current value} The bounded integer that
QRangeControl maintains. value() returns it, and several
functions, including setValue(), set it.
\i \e{Minimum} The lowest value that value() can ever
return. Returned by minValue() and set by setRange() or one of the
constructors.
\i \e{Maximum} The highest value that value() can ever
return. Returned by maxValue() and set by setRange() or one of the
constructors.
\i \e{Line step} The smaller of two natural steps that
QRangeControl provides and typically corresponds to the user
pressing an arrow key. The line step is returned by lineStep()
and set using setSteps(). The functions addLine() and
subtractLine() respectively increment and decrement the current
value by lineStep().
\i \e{Page step} The larger of two natural steps that
QRangeControl provides and typically corresponds to the user
pressing PageUp or PageDown. The page step is returned by
pageStep() and set using setSteps(). The functions addPage() and
substractPage() respectively increment and decrement the current
value by pageStep().
\endlist
Unity (1) may be viewed as a third step size. setValue() lets you
set the current value to any integer in the allowed range, not
just minValue() + \e n * lineStep() for integer values of \e n.
Some widgets may allow the user to set any value at all; others
may just provide multiples of lineStep() or pageStep().
QRangeControl provides three virtual functions that are well
suited for updating the on-screen representation of range controls
and emitting signals: valueChange(), rangeChange() and
stepChange().
QRangeControl also provides a function called bound() which lets
you force arbitrary integers to be within the allowed range of the
range control.
We recommend that all widgets that inherit QRangeControl provide
at least a signal called valueChanged(); many widgets will want to
provide addStep(), addPage(), substractStep() and substractPage()
as slots.
Note that you must use multiple inheritance if you plan to
implement a widget using QRangeControl because QRangeControl is
not derived from QWidget.
*/
/*!
Constructs a range control with a minimum value of 0, maximum
value of 99, line step of 1, page step of 10 and initial value 0.
*/
QRangeControl::QRangeControl()
{
minVal = 0;
maxVal = 99;
line = 1;
page = 10;
val = 0;
prevVal = -1;
d = 0;
}
/*!
Constructs a range control whose value can never be smaller than
\a minValue or greater than \a maxValue, whose line step size is
\a lineStep and page step size is \a pageStep and whose value is
initially \a value (which is guaranteed to be in range using
bound()).
*/
QRangeControl::QRangeControl( int minValue, int maxValue,
int lineStep, int pageStep,
int value )
{
minVal = minValue;
maxVal = maxValue;
line = QABS( lineStep );
page = QABS( pageStep );
prevVal = minVal - 1;
val = bound( value );
d = 0;
}
/*!
Destroys the range control
*/
QRangeControl::~QRangeControl()
{
}
/*!
\fn int QRangeControl::value() const
Returns the current range control value. This is guaranteed to be
within the range [minValue(), maxValue()].
\sa setValue() prevValue()
*/
/*!
\fn int QRangeControl::prevValue() const
Returns the previous value of the range control. "Previous value"
means the value before the last change occurred. Setting a new
range may affect the value, too, because the value is forced to be
inside the specified range. When the range control is initially
created, this is the same as value().
prevValue() can be outside the current legal range if a call to
setRange() causes the current value to change. For example, if the
range was [0, 1000] and the current value is 500, setRange(0, 400)
makes value() return 400 and prevValue() return 500.
\sa value() setRange()
*/
/*!
Sets the range control's value to \a value and forces it to be
within the legal range.
Calls the virtual valueChange() function if the new value is
different from the previous value. The old value can still be
retrieved using prevValue().
\sa value()
*/
void QRangeControl::setValue( int value )
{
directSetValue( value );
if ( prevVal != val )
valueChange();
}
/*!
Sets the range control \a value directly without calling
valueChange().
Forces the new \a value to be within the legal range.
You will rarely have to call this function. However, if you want
to change the range control's value inside the overloaded method
valueChange(), setValue() would call the function valueChange()
again. To avoid this recursion you must use directSetValue()
instead.
\sa setValue()
*/
void QRangeControl::directSetValue(int value)
{
prevVal = val;
val = bound( value );
}
/*!
Equivalent to \c{setValue( value() + pageStep() )}.
If the value is changed, then valueChange() is called.
\sa subtractPage() addLine() setValue()
*/
void QRangeControl::addPage()
{
if (!sumOutOfRange(value(), pageStep()))
setValue(value() + pageStep());
}
/*!
Equivalent to \c{setValue( value() - pageStep() )}.
If the value is changed, then valueChange() is called.
\sa addPage() subtractLine() setValue()
*/
void QRangeControl::subtractPage()
{
if (!sumOutOfRange(value(), -pageStep()))
setValue(value() - pageStep());
}
/*!
Equivalent to \c{setValue( value() + lineStep() )}.
If the value is changed, then valueChange() is called.
\sa subtractLine() addPage() setValue()
*/
void QRangeControl::addLine()
{
if (!sumOutOfRange(value(), lineStep()))
setValue(value() + lineStep());
}
/*!
Equivalent to \c{setValue( value() - lineStep() )}.
If the value is changed, then valueChange() is called.
\sa addLine() subtractPage() setValue()
*/
void QRangeControl::subtractLine()
{
if (!sumOutOfRange(value(), -lineStep()))
setValue(value() - lineStep());
}
/*!
\fn int QRangeControl::minValue() const
Returns the minimum value of the range.
\sa setMinValue() setRange() maxValue()
*/
/*!
\fn int QRangeControl::maxValue() const
Returns the maximum value of the range.
\sa setMaxValue() setRange() minValue()
*/
/*!
Sets the minimum value of the range to \a minVal.
If necessary, the maxValue() is adjusted so that the range remains
valid.
\sa minValue() setMaxValue()
*/
void QRangeControl::setMinValue( int minVal )
{
int maxVal = maxValue();
if ( maxVal < minVal )
maxVal = minVal;
setRange( minVal, maxVal );
}
/*!
Sets the minimum value of the range to \a maxVal.
If necessary, the minValue() is adjusted so that the range remains
valid.
\sa maxValue() setMinValue()
*/
void QRangeControl::setMaxValue( int maxVal )
{
int minVal = minValue();
if ( minVal > maxVal )
minVal = maxVal;
setRange( minVal, maxVal );
}
/*!
Sets the range control's minimum value to \a minValue and its
maximum value to \a maxValue.
Calls the virtual rangeChange() function if one or both of the new
minimum and maximum values are different from the previous
setting. Calls the virtual valueChange() function if the current
value is adjusted because it was outside the new range.
If \a maxValue is smaller than \a minValue, \a minValue becomes
the only legal value.
\sa minValue() maxValue()
*/
void QRangeControl::setRange( int minValue, int maxValue )
{
if ( minValue > maxValue ) {
#if defined(QT_CHECK_RANGE)
qWarning( "QRangeControl::setRange: minValue %d > maxValue %d",
minValue, maxValue );
#endif
maxValue = minValue;
}
if ( minValue == minVal && maxValue == maxVal )
return;
minVal = minValue;
maxVal = maxValue;
int tmp = bound( val );
rangeChange();
if ( tmp != val ) {
prevVal = val;
val = tmp;
valueChange();
}
}
/*!
\fn int QRangeControl::lineStep() const
Returns the line step.
\sa setSteps() pageStep()
*/
/*!
\fn int QRangeControl::pageStep() const
Returns the page step.
\sa setSteps() lineStep()
*/
/*!
Sets the range's line step to \a lineStep and page step to \a
pageStep.
Calls the virtual stepChange() function if the new line step
or page step are different from the previous settings.
\sa lineStep() pageStep() setRange()
*/
void QRangeControl::setSteps( int lineStep, int pageStep )
{
if ( lineStep != line || pageStep != page ) {
line = QABS( lineStep );
page = QABS( pageStep );
stepChange();
}
}
/*!
This virtual function is called whenever the range control value
changes. You can reimplement it if you want to be notified when
the value changes. The default implementation does nothing.
Note that this method is called after the value has changed. The
previous value can be retrieved using prevValue().
\sa setValue(), addPage(), subtractPage(), addLine(),
subtractLine() rangeChange(), stepChange()
*/
void QRangeControl::valueChange()
{
}
/*!
This virtual function is called whenever the range control's range
changes. You can reimplement it if you want to be notified when
the range changes. The default implementation does nothing.
Note that this method is called after the range has changed.
\sa setRange(), valueChange(), stepChange()
*/
void QRangeControl::rangeChange()
{
}
/*!
This virtual function is called whenever the range control's
line or page step settings change. You can reimplement it if you
want to be notified when the step changes. The default
implementation does nothing.
Note that this method is called after a step setting has changed.
\sa setSteps(), rangeChange(), valueChange()
*/
void QRangeControl::stepChange()
{
}
/*!
Forces the value \a v to be within the range from minValue() to
maxValue() inclusive, and returns the result.
This function is provided so that you can easily force other
numbers than value() into the allowed range. You do not need to
call it in order to use QRangeControl itself.
\sa setValue() value() minValue() maxValue()
*/
int QRangeControl::bound( int v ) const
{
if ( v < minVal )
return minVal;
if ( v > maxVal )
return maxVal;
return v;
}
/*!
Converts \a logical_val to a pixel position. minValue() maps to 0,
maxValue() maps to \a span and other values are distributed evenly
in-between.
This function can handle the entire integer range without
overflow, providing \a span is \<= 4096.
Calling this method is useful when actually drawing a range
control such as a QScrollBar on-screen.
\sa valueFromPosition()
*/
int QRangeControl::positionFromValue( int logical_val, int span ) const
{
if ( span <= 0 || logical_val < minValue() || maxValue() <= minValue() )
return 0;
if ( logical_val > maxValue() )
return span;
uint range = maxValue() - minValue();
uint p = logical_val - minValue();
if ( range > (uint)INT_MAX/4096 ) {
const int scale = 4096*2;
return ( (p/scale) * span ) / (range/scale);
// ### the above line is probably not 100% correct
// ### but fixing it isn't worth the extreme pain...
} else if ( range > (uint)span ) {
return (2*p*span + range) / (2*range);
} else {
uint div = span / range;
uint mod = span % range;
return p*div + (2*p*mod + range) / (2*range);
}
//equiv. to (p*span)/range + 0.5
// no overflow because of this implicit assumption:
// span <= 4096
}
/*!
Converts the pixel position \a pos to a value. 0 maps to
minValue(), \a span maps to maxValue() and other values are
distributed evenly in-between.
This function can handle the entire integer range without
overflow.
Calling this method is useful if you actually implemented a range
control widget such as QScrollBar and want to handle mouse press
events. This function then maps screen coordinates to the logical
values.
\sa positionFromValue()
*/
int QRangeControl::valueFromPosition( int pos, int span ) const
{
if ( span <= 0 || pos <= 0 )
return minValue();
if ( pos >= span )
return maxValue();
uint range = maxValue() - minValue();
if ( (uint)span > range )
return minValue() + (2*pos*range + span) / (2*span);
else {
uint div = range / span;
uint mod = range % span;
return minValue() + pos*div + (2*pos*mod + span) / (2*span);
}
// equiv. to minValue() + (pos*range)/span + 0.5
// no overflow because of this implicit assumption:
// pos <= span < sqrt(INT_MAX+0.0625)+0.25 ~ sqrt(INT_MAX)
}
static bool sumOutOfRange(int current, int add)
{
if (add > 0 && INT_MAX - add < current) {
return true;
}
if (add < 0 && INT_MIN - add > current) {
return true;
}
return false;
}
#endif