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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<h1 align=center>QRangeControl Class Reference</h1><br clear="all">
<p>
The QRangeControl class provides an integer value within a range.
<a href="#details">More...</a>
<p>
<code>#include <<a href="qrangecontrol-h.html">qrangecontrol.h</a>></code>
<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="#b553d9"><b>QRangeControl</b></a>()</div>
<li><div class="fn"><a href="#8d3621"><b>QRangeControl</b></a>(intminValue, intmaxValue, intlineStep, intpageStep, intvalue)</div>
<li><div class="fn">int<a href="#1d2129"><b>value</b></a>()const</div>
<li><div class="fn">void<a href="#bc1c05"><b>setValue</b></a>(int)</div>
<li><div class="fn">void<a href="#25562d"><b>addPage</b></a>()</div>
<li><div class="fn">void<a href="#e20fb2"><b>subtractPage</b></a>()</div>
<li><div class="fn">void<a href="#0767c3"><b>addLine</b></a>()</div>
<li><div class="fn">void<a href="#caed18"><b>subtractLine</b></a>()</div>
<li><div class="fn">int<a href="#046e8a"><b>minValue</b></a>()const</div>
<li><div class="fn">int<a href="#541e49"><b>maxValue</b></a>()const</div>
<li><div class="fn">void<a href="#f2409c"><b>setRange</b></a>(intminValue, intmaxValue)</div>
<li><div class="fn">int<a href="#7c7645"><b>lineStep</b></a>()const</div>
<li><div class="fn">int<a href="#082f80"><b>pageStep</b></a>()const</div>
<li><div class="fn">void<a href="#1b6f6d"><b>setSteps</b></a>(intline, intpage)</div>
<li><div class="fn">int<a href="#f0c04b"><b>bound</b></a>(int)const</div>
</ul>
<h2>Protected Members</h2>
<ul>
<li><div class="fn">int<a href="#257f95"><b>positionFromValue</b></a>(intval, intspace)const</div>
<li><div class="fn">int<a href="#09b78d"><b>valueFromPosition</b></a>(intpos, intspace)const</div>
<li><div class="fn">void<a href="#702e84"><b>directSetValue</b></a>(intval)</div>
<li><div class="fn">int<a href="#e1455d"><b>prevValue</b></a>()const</div>
<li><div class="fn">virtualvoid<a href="#671dc3"><b>valueChange</b></a>()</div>
<li><div class="fn">virtualvoid<a href="#a849c2"><b>rangeChange</b></a>()</div>
<li><div class="fn">virtualvoid<a href="#e0aaf5"><b>stepChange</b></a>()</div>
</ul>
<hr><h2><a name="details"></a>Detailed Description</h2>
The QRangeControl class provides an integer value within a range.
<p>
It was originally designed for the <a href="qscrollbar.html">QScrollBar</a> widget, but it can
also be practical for other purposes such as <a href="qslider.html">QSlider</a> and <a href="qspinbox.html">QSpinBox</a>.
Here are the five main concepts in the class: <ul>
<li> The current value. This is the bounded integer that
QRangeControl maintains. <a href="#1d2129">value</a>() returns this, and several
functions including <a href="#bc1c05">setValue</a>() set it.
<li> The minimum. This is the lowest value value() can ever return.
Returned by <a href="#046e8a">minValue</a>(), set by <a href="#f2409c">setRange</a>() or one of the
constructors.
<li> The maximum. This is the highest value value() can ever return.
Returned by <a href="#541e49">maxValue</a>(), set by setRange() or one of the
constructors.
<li> The line step. This is the smaller of two natural steps
QRangeControl provides, and typically corresponds to the user
pressing an arrow key. The line step is returned by <a href="#7c7645">lineStep</a>()
and set using <a href="#1b6f6d">setSteps</a>(). The functions <a href="#0767c3">addLine</a>() and <a href="#caed18">subtractLine</a>() allow easy
movement of the current value by lineStep().
<li> The page step. This is the larger of two natural steps
QRangeControl provides, and typically corresponds to the user
pressing one of the PageUp and PageDown keys. The page step is
returned by <a href="#082f80">pageStep</a>() and set using setSteps().
The functions <a href="#25562d">addPage</a>() and substractPage() allow easy movement
of the current value by pageStep().
<p></ul>
<p>Note that 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()+<a href="n.html">n</a>*lineStep() for integer values of n. Some
widgets may allow the user to set any value at all, others may just
provide multiples of lineStep()/pageStep().
<p>QRangeControl provides three virtual functions that are well-suited
e.g. for updating the on-screen representation of range controls and
emitting signals, namely <a href="#671dc3">valueChange</a>(), <a href="#a849c2">rangeChange</a>() and
<a href="#e0aaf5">stepChange</a>().
<p>Finally, QRangeControl provides a function called <a href="#f0c04b">bound</a>() which lets you
force arbitrary integers to be within the allowed range of the range control.
<p>We recommend that all widgets, which inherit QRangeControl,
provide at least a signal called
valueChanged(), and many widgets will want to provide addStep(),
addPage(), substractStep() and substractPage() as slots.
<p>Note that you have to use multiple inheritance if you plan to implement
a widget using QRangeControl, since QRangeControl is not derived from
<a href="qwidget.html">QWidget</a>.
<hr><h2>Member Function Documentation</h2>
<h3 class="fn"><a name="b553d9"></a>QRangeControl::QRangeControl()</h3>
<p>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="8d3621"></a>QRangeControl::QRangeControl(intminValue, intmaxValue, intlineStep, intpageStep, intvalue)</h3>
<p>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>
<p><em>value</em> is forced to be within the legal range using the <a href="#f0c04b">bound</a>() method.
<h3 class="fn">void<a name="0767c3"></a>QRangeControl::addLine()</h3>
<p>Equivalent to <pre> setValue( value()+lineStep() )</pre>
plus a
test for numerical overflow
<p>If the value is changed, then <a href="#671dc3">valueChange</a>() is called.
<p>See also <a href="#caed18">subtractLine</a>(), <a href="#25562d">addPage</a>() and <a href="#bc1c05">setValue</a>().
<h3 class="fn">void<a name="25562d"></a>QRangeControl::addPage()</h3>
<p>Equivalent to <pre> setValue( value()+pageStep() )</pre>
plus a
test for numerical overflow.
<p>If the value is changed, then <a href="#671dc3">valueChange</a>() is called.
<p>See also <a href="#e20fb2">subtractPage</a>(), <a href="#0767c3">addLine</a>() and <a href="#bc1c05">setValue</a>().
<h3 class="fn">int<a name="f0c04b"></a>QRangeControl::bound(intv)const</h3>
<p>Forces <em>v</em> to be within the range from <a href="#046e8a">minValue</a>() to <a href="#541e49">maxValue</a>()
inclusive, and returns the result.
<p>This function is provided so that you can easily force other numbers
than <a href="#1d2129">value</a>() into the allowed range. You do not need to call it in
order to use QRangeControl itself.
<p>See also <a href="#bc1c05">setValue</a>(), <a href="#1d2129">value</a>(), <a href="#046e8a">minValue</a>() and <a href="#541e49">maxValue</a>().
<h3 class="fn">void<a name="702e84"></a>QRangeControl::directSetValue(intvalue) <code>[protected]</code></h3>
<p>Sets the range control value directly without calling <a href="#671dc3">valueChange</a>().
<p>Forces the new value to be within the legal range.
<p>You will find few cases only where you have to call this function.
However, if you want to change the range controls value inside
the overloaded method valueChange() then <a href="#bc1c05">setValue</a>() would call the
function valueChange() again. To avoid this recursion you must use
directSetValue() instead.
<p>See also <a href="#bc1c05">setValue</a>().
<h3 class="fn">int<a name="7c7645"></a>QRangeControl::lineStep()const</h3>
<p>Returns the current line step.
<p>See also <a href="#1b6f6d">setSteps</a>() and <a href="#082f80">pageStep</a>().
<h3 class="fn">int<a name="541e49"></a>QRangeControl::maxValue()const</h3>
<p>Returns the current maximum value of the range.
<p>See also <a href="#f2409c">setRange</a>() and <a href="#046e8a">minValue</a>().
<h3 class="fn">int<a name="046e8a"></a>QRangeControl::minValue()const</h3>
<p>Returns the current minimum value of the range.
<p>See also <a href="#f2409c">setRange</a>() and <a href="#541e49">maxValue</a>().
<h3 class="fn">int<a name="082f80"></a>QRangeControl::pageStep()const</h3>
<p>Returns the current page step.
<p>See also <a href="#1b6f6d">setSteps</a>() and <a href="#7c7645">lineStep</a>().
<h3 class="fn">int<a name="257f95"></a>QRangeControl::positionFromValue(intlogical_val, intspan)const <code>[protected]</code></h3>
<p>Converts <em>logical_val</em> to a pixel position. <a href="#046e8a">minValue</a>() maps to 0, <a href="#541e49">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>Callings this method is useful when actually drawing a range control
like a <a href="qscrollbar.html">QScrollBar</a> on the screen.
<p>See also <a href="#09b78d">valueFromPosition</a>().
<h3 class="fn">int<a name="e1455d"></a>QRangeControl::prevValue()const <code>[protected]</code></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, since the value is forced to be inside
the specified range. When the range
control is initially created, this is the same as <a href="#1d2129">value</a>().
<p>Note that prevValue() can be outside the current legal range if a call to
<a href="#f2409c">setRange</a>() causes the current value to change. (For example if the
range was 0-1000 and the current value 500, setRange( 0, 400 ) makes
value() return 400 and prevValue() 500)
<p>See also <a href="#1d2129">value</a>() and <a href="#f2409c">setRange</a>().
<h3 class="fn">void<a name="a849c2"></a>QRangeControl::rangeChange() <code>[virtualprotected]</code></h3>
<p>This virtual function is called whenever the range controls 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>See also <a href="#f2409c">setRange</a>(), <a href="#671dc3">valueChange</a>() and <a href="#e0aaf5">stepChange</a>().
<p>Reimplemented in <a href="qdial.html#ecbfec">QDial</a>, <a href="qslider.html#cb0cf3">QSlider</a> and <a href="qscrollbar.html#2932d5">QScrollBar</a>.
<h3 class="fn">void<a name="f2409c"></a>QRangeControl::setRange(intminValue, intmaxValue)</h3>
<p>Sets the range min value to <em>minValue</em> and the max value to <em>maxValue.</em>
<p>Calls the virtual <a href="#a849c2">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="#671dc3">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, minValue</em> becomes the
only legal value.
<p>See also <a href="#046e8a">minValue</a>() and <a href="#541e49">maxValue</a>().
<p>Examples:
<a href="xform-xform-cpp.html#setRange">xform/xform.cpp</a>
<h3 class="fn">void<a name="1b6f6d"></a>QRangeControl::setSteps(intlineStep,intpageStep)</h3>
<p>Sets the range line step to <em>lineStep</em> and page step to <em>pageStep.</em>
<p>Calls the virtual <a href="#e0aaf5">stepChange</a>() function if the new line step and/or
page step are different from the previous settings.
<p>See also <a href="#7c7645">lineStep</a>(), <a href="#082f80">pageStep</a>() and <a href="#f2409c">setRange</a>().
<h3 class="fn">void<a name="bc1c05"></a>QRangeControl::setValue(intvalue)</h3>
<p>Sets the range controls value to <em>value</em> and forces it to be within
the legal range.
<p>Calls the virtual <a href="#671dc3">valueChange</a>() function if the new value is
different from the previous value. The old value can still be
retrieved using <a href="#e1455d">prevValue</a>().
<p>See also <a href="#1d2129">value</a>().
<h3 class="fn">void<a name="e0aaf5"></a>QRangeControl::stepChange() <code>[virtualprotected]</code></h3>
<p>This virtual function is called whenever the range controls line/page step
settings changes. 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 changed.
<p>See also <a href="#1b6f6d">setSteps</a>(), <a href="#a849c2">rangeChange</a>() and <a href="#671dc3">valueChange</a>().
<p>Reimplemented in <a href="qscrollbar.html#5b784a">QScrollBar</a>.
<h3 class="fn">void<a name="caed18"></a>QRangeControl::subtractLine()</h3>
<p>Equivalent to <pre> setValue( value()-lineStep() )</pre>
plus a
test for numerical underflow
<p>If the value is changed, then <a href="#671dc3">valueChange</a>() is called.
<p>See also <a href="#0767c3">addLine</a>(), <a href="#e20fb2">subtractPage</a>() and <a href="#bc1c05">setValue</a>().
<h3 class="fn">void<a name="e20fb2"></a>QRangeControl::subtractPage()</h3>
<p>Equivalent to <pre> setValue( value()-pageStep() )</pre>
plus a
test for numerical underflow
<p>If the value is changed, then <a href="#671dc3">valueChange</a>() is called.
<p>See also <a href="#25562d">addPage</a>(), <a href="#caed18">subtractLine</a>() and <a href="#bc1c05">setValue</a>().
<h3 class="fn">int<a name="1d2129"></a>QRangeControl::value()const</h3>
<p>Returns the current range control value. This is guaranteed to be
within the range [ <a href="#046e8a">minValue</a>() ... <a href="#541e49">maxValue</a>() ].
<p>See also <a href="#bc1c05">setValue</a>() and <a href="#e1455d">prevValue</a>().
<h3 class="fn">void<a name="671dc3"></a>QRangeControl::valueChange() <code>[virtualprotected]</code></h3>
<p>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="#e1455d">prevValue</a>().
<p>See also <a href="#bc1c05">setValue</a>(), <a href="#25562d">addPage</a>(), <a href="#e20fb2">subtractPage</a>(), <a href="#0767c3">addLine</a>(), <a href="#caed18">subtractLine</a>(), <a href="#a849c2">rangeChange</a>() and <a href="#e0aaf5">stepChange</a>().
<p>Reimplemented in <a href="qslider.html#70a497">QSlider</a>, <a href="qscrollbar.html#5e0382">QScrollBar</a> and <a href="qdial.html#c1c8f5">QDial</a>.
<h3 class="fn">int<a name="09b78d"></a>QRangeControl::valueFromPosition(intpos, intspan)const <code>[protected]</code></h3>
<p>Converts the pixel position <em>pos</em> to a value. 0 maps to <a href="#046e8a">minValue</a>(),
<em>span</em> maps to <a href="#541e49">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 like <a href="qscrollbar.html">QScrollBar</a> and want to handle mouse press events. This function
maps then screen coordinates to the logical values.
<p>See also <a href="#257f95">positionFromValue</a>().
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