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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QRangeControl Class Reference</h1>
<p>The QRangeControl class provides an integer value within a range.
<a href="#details">More...</a>
<p><tt>#include <<a href="qrangecontrol-h.html">qrangecontrol.h</a>></tt>
<p>Inherited by <a href="qdial.html">QDial</a>, <a href="qscrollbar.html">QScrollBar</a>, <a href="qslider.html">QSlider</a> and <a href="qspinbox.html">QSpinBox</a>.
<p><a href="qrangecontrol-members.html">List of all member functions.</a>
<h2>Public Members</h2>
<ul>
<li><div class=fn><a href="#QRangeControl"><b>QRangeControl</b></a> ()</div></li>
<li><div class=fn><a href="#QRangeControl-2"><b>QRangeControl</b></a> ( int minValue, int maxValue, int lineStep, int pageStep, int value )</div></li>
<li><div class=fn>virtual <a href="#~QRangeControl"><b>~QRangeControl</b></a> ()</div></li>
<li><div class=fn>int <a href="#value"><b>value</b></a> () const</div></li>
<li><div class=fn>void <a href="#setValue"><b>setValue</b></a> ( int value )</div></li>
<li><div class=fn>void <a href="#addPage"><b>addPage</b></a> ()</div></li>
<li><div class=fn>void <a href="#subtractPage"><b>subtractPage</b></a> ()</div></li>
<li><div class=fn>void <a href="#addLine"><b>addLine</b></a> ()</div></li>
<li><div class=fn>void <a href="#subtractLine"><b>subtractLine</b></a> ()</div></li>
<li><div class=fn>int <a href="#minValue"><b>minValue</b></a> () const</div></li>
<li><div class=fn>int <a href="#maxValue"><b>maxValue</b></a> () const</div></li>
<li><div class=fn>void <a href="#setRange"><b>setRange</b></a> ( int minValue, int maxValue )</div></li>
<li><div class=fn>void <a href="#setMinValue"><b>setMinValue</b></a> ( int minVal )</div></li>
<li><div class=fn>void <a href="#setMaxValue"><b>setMaxValue</b></a> ( int maxVal )</div></li>
<li><div class=fn>int <a href="#lineStep"><b>lineStep</b></a> () const</div></li>
<li><div class=fn>int <a href="#pageStep"><b>pageStep</b></a> () const</div></li>
<li><div class=fn>void <a href="#setSteps"><b>setSteps</b></a> ( int lineStep, int pageStep )</div></li>
<li><div class=fn>int <a href="#bound"><b>bound</b></a> ( int v ) const</div></li>
</ul>
<h2>Protected Members</h2>
<ul>
<li><div class=fn>int <a href="#positionFromValue"><b>positionFromValue</b></a> ( int logical_val, int span ) const</div></li>
<li><div class=fn>int <a href="#valueFromPosition"><b>valueFromPosition</b></a> ( int pos, int span ) const</div></li>
<li><div class=fn>void <a href="#directSetValue"><b>directSetValue</b></a> ( int value )</div></li>
<li><div class=fn>int <a href="#prevValue"><b>prevValue</b></a> () const</div></li>
<li><div class=fn>virtual void <a href="#valueChange"><b>valueChange</b></a> ()</div></li>
<li><div class=fn>virtual void <a href="#rangeChange"><b>rangeChange</b></a> ()</div></li>
<li><div class=fn>virtual void <a href="#stepChange"><b>stepChange</b></a> ()</div></li>
</ul>
<hr><a name="details"></a><h2>Detailed Description</h2>
The QRangeControl class provides an integer value within a range.
<p>
<p> Although originally designed for the <a href="qscrollbar.html">QScrollBar</a> widget, the
QRangeControl can also be used in conjunction with other widgets
such as <a href="qslider.html">QSlider</a> and <a href="qspinbox.html">QSpinBox</a>. Here are the five main concepts in the
class:
<p> <ol type=1>
<p> <li> Current value. This is the bounded integer that
QRangeControl maintains. <a href="#value">value</a>() returns this and several
functions, including <a href="#setValue">setValue</a>(), set it.
<p> <li> Minimum. This is the lowest value that value() can ever
return. Returned by <a href="#minValue">minValue</a>() and set by <a href="#setRange">setRange</a>() or one of the
constructors.
<p> <li> Maximum. This is the highest value that value() can ever
return. Returned by <a href="#maxValue">maxValue</a>() and set by setRange() or one of the
constructors.
<p> <li> Line step. This is 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 <a href="#lineStep">lineStep</a>() and
set using <a href="#setSteps">setSteps</a>(). The functions <a href="#addLine">addLine</a>() and <a href="#subtractLine">subtractLine</a>()
respectively increment and decrement the current value by lineStep().
<p> <li> Page step. This is 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 <a href="#pageStep">pageStep</a>() and set using setSteps(). The functions
<a href="#addPage">addPage</a>() and substractPage() respectively increment and decrement
the current value by pageStep().
<p> </ol>
<p> Unity (1) may be viewed as a third step size. <a href="#setValue">setValue</a>() lets you
set the current value to any integer in the allowed range, not just
<a href="#minValue">minValue</a>() + <em>n</em> * lineStep() for integer values of <em>n</em>. Some
widgets may allow the user to set any value at all; others may just
provide multiples of lineStep() or pageStep().
<p> QRangeControl provides three virtual functions that are well suited
for updating the on-screen representation of range controls and
emitting signals, namely <a href="#valueChange">valueChange</a>(), <a href="#rangeChange">rangeChange</a>() and
<a href="#stepChange">stepChange</a>().
<p> QRangeControl also provides a function called <a href="#bound">bound</a>() which
lets you force arbitrary integers to be within the allowed range of
the range control.
<p> We recommend that all widgets that inherit QRangeControl provide at
least a signal called valueChanged(); many widgets will want to
provide addStep(), <a href="#addPage">addPage</a>(), substractStep() and substractPage() as
slots.
<p> Note that you have to use multiple inheritance if you plan to implement
a widget using QRangeControl because QRangeControl is not derived from
<a href="qwidget.html">QWidget</a>.
<p>See also <a href="misc.html">Miscellaneous Classes</a>.
<hr><h2>Member Function Documentation</h2>
<h3 class=fn><a name="QRangeControl"></a>QRangeControl::QRangeControl ()
</h3>
Constructs a range control with min value 0, max value 99,
line step 1, page step 10 and initial value 0.
<h3 class=fn><a name="QRangeControl-2"></a>QRangeControl::QRangeControl ( int minValue, int maxValue, int lineStep, int pageStep, int value )
</h3>
Constructs a range control whose value can never be smaller than <em>minValue</em> or greater than <em>maxValue</em>, whose line step size is <em>lineStep</em> and page step size is <em>pageStep</em> and whose value is
initially <em>value</em> (which is guaranteed to be in range using <a href="#bound">bound</a>()).
<h3 class=fn><a name="~QRangeControl"></a>QRangeControl::~QRangeControl ()<tt> [virtual]</tt>
</h3>
Destroys the range control
<h3 class=fn>void <a name="addLine"></a>QRangeControl::addLine ()
</h3>
Equivalent to <tt>setValue( value() + lineStep() )</tt>.
<p> If the value is changed, then <a href="#valueChange">valueChange</a>() is called.
<p> <p>See also <a href="#subtractLine">subtractLine</a>(), <a href="#addPage">addPage</a>() and <a href="#setValue">setValue</a>().
<h3 class=fn>void <a name="addPage"></a>QRangeControl::addPage ()
</h3>
Equivalent to <tt>setValue( value() + pageStep() )</tt>.
<p> If the value is changed, then <a href="#valueChange">valueChange</a>() is called.
<p> <p>See also <a href="#subtractPage">subtractPage</a>(), <a href="#addLine">addLine</a>() and <a href="#setValue">setValue</a>().
<h3 class=fn>int <a name="bound"></a>QRangeControl::bound ( int v ) const
</h3> Forces the value <em>v</em> to be within the range from <a href="#minValue">minValue</a>() to
<a href="#maxValue">maxValue</a>() inclusive, and returns the result.
<p> This function is provided so that you can easily force other numbers
than <a href="#value">value</a>() into the allowed range. You do not need to call it in
order to use QRangeControl itself.
<p> <p>See also <a href="#setValue">setValue</a>(), <a href="#value">value</a>(), <a href="#minValue">minValue</a>() and <a href="#maxValue">maxValue</a>().
<h3 class=fn>void <a name="directSetValue"></a>QRangeControl::directSetValue ( int value )<tt> [protected]</tt>
</h3>
Sets the range control <em>value</em> directly without calling <a href="#valueChange">valueChange</a>().
<p> Forces the new <em>value</em> to be within the legal range.
<p> You will rarely have to call this function. However, if you want to
change the range control's value inside the overloaded method
valueChange(), <a href="#setValue">setValue</a>() would call the function valueChange()
again. To avoid this recursion you must use <a href="#directSetValue">directSetValue</a>()
instead.
<p> <p>See also <a href="#setValue">setValue</a>().
<h3 class=fn>int <a name="lineStep"></a>QRangeControl::lineStep () const
</h3>
<p> Returns the current line step.
<p> <p>See also <a href="#setSteps">setSteps</a>() and <a href="#pageStep">pageStep</a>().
<h3 class=fn>int <a name="maxValue"></a>QRangeControl::maxValue () const
</h3>
<p> Returns the current maximum value of the range.
<p> <p>See also <a href="#setMaxValue">setMaxValue</a>(), <a href="#setRange">setRange</a>() and <a href="#minValue">minValue</a>().
<h3 class=fn>int <a name="minValue"></a>QRangeControl::minValue () const
</h3>
<p> Returns the current minimum value of the range.
<p> <p>See also <a href="#setMinValue">setMinValue</a>(), <a href="#setRange">setRange</a>() and <a href="#maxValue">maxValue</a>().
<h3 class=fn>int <a name="pageStep"></a>QRangeControl::pageStep () const
</h3>
<p> Returns the current page step.
<p> <p>See also <a href="#setSteps">setSteps</a>() and <a href="#lineStep">lineStep</a>().
<h3 class=fn>int <a name="positionFromValue"></a>QRangeControl::positionFromValue ( int logical_val, int span ) const<tt> [protected]</tt>
</h3>
Converts <em>logical_val</em> to a pixel position. <a href="#minValue">minValue</a>() maps to 0,
<a href="#maxValue">maxValue</a>() maps to <em>span</em> and other values are distributed evenly
in-between.
<p> This function can handle the entire integer range without overflow.
<p> Calling this method is useful when actually drawing a range control
such as a <a href="qscrollbar.html">QScrollBar</a> on-screen.
<p> <p>See also <a href="#valueFromPosition">valueFromPosition</a>().
<h3 class=fn>int <a name="prevValue"></a>QRangeControl::prevValue () const<tt> [protected]</tt>
</h3>
<p> 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 <a href="#value">value</a>().
<p> <a href="#prevValue">prevValue</a>() can be outside the current legal range if a call to
<a href="#setRange">setRange</a>() 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.
<p> <p>See also <a href="#value">value</a>() and <a href="#setRange">setRange</a>().
<h3 class=fn>void <a name="rangeChange"></a>QRangeControl::rangeChange ()<tt> [virtual protected]</tt>
</h3>
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.
<p> Note that this method is called after the range changed.
<p> <p>See also <a href="#setRange">setRange</a>(), <a href="#valueChange">valueChange</a>() and <a href="#stepChange">stepChange</a>().
<p>Reimplemented in <a href="qdial.html#rangeChange">QDial</a>, <a href="qslider.html#rangeChange">QSlider</a> and <a href="qspinbox.html#rangeChange">QSpinBox</a>.
<h3 class=fn>void <a name="setMaxValue"></a>QRangeControl::setMaxValue ( int maxVal )
</h3>
Sets the current minimum value of the range to <em>maxVal</em>.
<p> If necessary, the <a href="#minValue">minValue</a>() is adjusted so that the range remains
valid.
<p> <p>See also <a href="#maxValue">maxValue</a>() and <a href="#setMinValue">setMinValue</a>().
<h3 class=fn>void <a name="setMinValue"></a>QRangeControl::setMinValue ( int minVal )
</h3>
Sets the current minimum value of the range to <em>minVal</em>.
<p> If necessary, the <a href="#maxValue">maxValue</a>() is adjusted so that the range remains
valid.
<p> <p>See also <a href="#minValue">minValue</a>() and <a href="#setMaxValue">setMaxValue</a>().
<h3 class=fn>void <a name="setRange"></a>QRangeControl::setRange ( int minValue, int maxValue )
</h3>
Sets the range control's min value to <em>minValue</em> and its max value
to <em>maxValue</em>.
<p> Calls the virtual <a href="#rangeChange">rangeChange</a>() function if one or both of the new
min and max values are different from the previous setting. Calls
the virtual <a href="#valueChange">valueChange</a>() function if the current value is adjusted
because it was outside the new range.
<p> If <em>maxValue</em> is smaller than <em>minValue</em>, <em>minValue</em> becomes the
only legal value.
<p> <p>See also <a href="#minValue">minValue</a>() and <a href="#maxValue">maxValue</a>().
<p>Examples: <a href="listbox-example.html#x1282">listbox/listbox.cpp</a>, <a href="t12.html#x2200">t12/lcdrange.cpp</a>, <a href="t5.html#x2128">t5/main.cpp</a>, <a href="t6.html#x2138">t6/main.cpp</a>, <a href="t8.html#x2147">t8/lcdrange.cpp</a> and <a href="xform-example.html#x106">xform/xform.cpp</a>.
<h3 class=fn>void <a name="setSteps"></a>QRangeControl::setSteps ( int lineStep, int pageStep )
</h3>
Sets the range line step to <em>lineStep</em> and page step to <em>pageStep</em>.
<p> Calls the virtual <a href="#stepChange">stepChange</a>() function if the new line step and/or
page step are different from the previous settings.
<p> <p>See also <a href="#lineStep">lineStep</a>(), <a href="#pageStep">pageStep</a>() and <a href="#setRange">setRange</a>().
<h3 class=fn>void <a name="setValue"></a>QRangeControl::setValue ( int value )
</h3>
Sets the range control's value to <em>value</em> and forces it to be within
the legal range.
<p> Calls the virtual <a href="#valueChange">valueChange</a>() function if the new value is
different from the previous value. The old value can still be
retrieved using <a href="#prevValue">prevValue</a>().
<p> <p>See also <a href="#value">value</a>().
<h3 class=fn>void <a name="stepChange"></a>QRangeControl::stepChange ()<tt> [virtual protected]</tt>
</h3>
This virtual function is called whenever the range control's
line/page step settings change. You can reimplement it if you want
to be notified when the step changes. The default implementation
does nothing.
<p> Note that this method is called after the step settings change.
<p> <p>See also <a href="#setSteps">setSteps</a>(), <a href="#rangeChange">rangeChange</a>() and <a href="#valueChange">valueChange</a>().
<h3 class=fn>void <a name="subtractLine"></a>QRangeControl::subtractLine ()
</h3>
Equivalent to <tt>setValue( value() - lineStep() )</tt>.
<p> If the value is changed, then <a href="#valueChange">valueChange</a>() is called.
<p> <p>See also <a href="#addLine">addLine</a>(), <a href="#subtractPage">subtractPage</a>() and <a href="#setValue">setValue</a>().
<h3 class=fn>void <a name="subtractPage"></a>QRangeControl::subtractPage ()
</h3>
Equivalent to <tt>setValue( value() - pageStep() )</tt>.
<p> If the value is changed, then <a href="#valueChange">valueChange</a>() is called.
<p> <p>See also <a href="#addPage">addPage</a>(), <a href="#subtractLine">subtractLine</a>() and <a href="#setValue">setValue</a>().
<h3 class=fn>int <a name="value"></a>QRangeControl::value () const
</h3>
<p> Returns the current range control value. This is guaranteed to be
within the range [minValue(), <a href="#maxValue">maxValue</a>()].
<p> <p>See also <a href="#setValue">setValue</a>() and <a href="#prevValue">prevValue</a>().
<h3 class=fn>void <a name="valueChange"></a>QRangeControl::valueChange ()<tt> [virtual protected]</tt>
</h3>
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.
<p> Note that this method is called after the value changed. The previous
value can be retrieved using <a href="#prevValue">prevValue</a>().
<p> <p>See also <a href="#setValue">setValue</a>(), <a href="#addPage">addPage</a>(), <a href="#subtractPage">subtractPage</a>(), <a href="#addLine">addLine</a>(), <a href="#subtractLine">subtractLine</a>(), <a href="#rangeChange">rangeChange</a>() and <a href="#stepChange">stepChange</a>().
<p>Reimplemented in <a href="qdial.html#valueChange">QDial</a>, <a href="qslider.html#valueChange">QSlider</a> and <a href="qspinbox.html#valueChange">QSpinBox</a>.
<h3 class=fn>int <a name="valueFromPosition"></a>QRangeControl::valueFromPosition ( int pos, int span ) const<tt> [protected]</tt>
</h3>
Converts the pixel position <em>pos</em> to a value. 0 maps to <a href="#minValue">minValue</a>(),
<em>span</em> maps to <a href="#maxValue">maxValue</a>() and other values are distributed evenly
in-between.
<p> This function can handle the entire integer range without overflow.
<p> Calling this method is useful if you actually implemented a range
control widget such as <a href="qscrollbar.html">QScrollBar</a> and want to handle mouse press
events. This function then maps screen coordinates to the logical
values.
<p> <p>See also <a href="#positionFromValue">positionFromValue</a>().
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