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authorTimothy Pearson <kb9vqf@pearsoncomputing.net>2011-07-10 15:24:15 -0500
committerTimothy Pearson <kb9vqf@pearsoncomputing.net>2011-07-10 15:24:15 -0500
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tree7a520322212d48ebcb9fbe1087e7fca28b76185c /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