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<td width="1"> </td><td class="postheader" valign="center"><a href="index.html"><font color="#004faf">Home</font></a> · <a href="classes.html"><font color="#004faf">All Classes</font></a> · <a href="functions.html"><font color="#004faf">All Functions</font></a> · <a href="overviews.html"><font color="#004faf">Overviews</font></a></td></tr></table><h1 class="title">QFlags Class Reference<br /><span class="small-subtitle">[<a href="qtcore.html">QtCore</a> module]</span>
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<p>The QFlags class provides a type-safe way of storing OR-combinations of enum values. <a href="#details">More...</a></p>
<pre> #include <QFlags></pre><ul>
<li><a href="qflags-members.html">List of all members, including inherited members</a></li>
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<a name="public-types"></a>
<h2>Public Types</h2>
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<tr><td class="memItemLeft" align="right" valign="top">typedef </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#enum_type-typedef">enum_type</a></b></td></tr>
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<a name="public-functions"></a>
<h2>Public Functions</h2>
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<tr><td class="memItemLeft" align="right" valign="top"></td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#QFlags">QFlags</a></b> ( const QFlags & <i>other</i> )</td></tr>
<tr><td class="memItemLeft" align="right" valign="top"></td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#QFlags-2">QFlags</a></b> ( Enum <i>flag</i> )</td></tr>
<tr><td class="memItemLeft" align="right" valign="top"></td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#QFlags-3">QFlags</a></b> ( Zero <i>zero</i> = 0 )</td></tr>
<tr><td class="memItemLeft" align="right" valign="top"></td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#QFlags-4">QFlags</a></b> ( QFlag <i>value</i> )</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">bool </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#testFlag">testFlag</a></b> ( Enum <i>flag</i> ) const</td></tr>
<tr><td class="memItemLeft" align="right" valign="top"></td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-int">operator int</a></b> () const</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">bool </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-not">operator!</a></b> () const</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-and">operator&</a></b> ( int <i>mask</i> ) const</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-and-2">operator&</a></b> ( uint <i>mask</i> ) const</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-and-3">operator&</a></b> ( Enum <i>mask</i> ) const</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags & </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-and-eq">operator&=</a></b> ( int <i>mask</i> )</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags & </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-and-eq-2">operator&=</a></b> ( uint <i>mask</i> )</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags & </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-eq">operator=</a></b> ( const QFlags & <i>other</i> )</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-5e">operator^</a></b> ( QFlags <i>other</i> ) const</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-5e-2">operator^</a></b> ( Enum <i>other</i> ) const</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags & </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-5e-eq">operator^=</a></b> ( QFlags <i>other</i> )</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags & </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-5e-eq-2">operator^=</a></b> ( Enum <i>other</i> )</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-7c">operator|</a></b> ( QFlags <i>other</i> ) const</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-7c-2">operator|</a></b> ( Enum <i>other</i> ) const</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags & </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-7c-eq">operator|=</a></b> ( QFlags <i>other</i> )</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags & </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-7c-eq-2">operator|=</a></b> ( Enum <i>other</i> )</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QFlags </td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#operator-7e">operator~</a></b> () const</td></tr>
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<hr />
<a name="macros"></a>
<h2>Macros</h2>
<table class="alignedsummary" border="0" cellpadding="0" cellspacing="0" width="100%">
<tr><td class="memItemLeft" align="right" valign="top"></td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#Q_DECLARE_FLAGS">Q_DECLARE_FLAGS</a></b> ( <i>Flags</i>, <i>Enum</i> )</td></tr>
<tr><td class="memItemLeft" align="right" valign="top"></td><td class="memItemRight" valign="bottom"><b><a href="qflags.html#Q_DECLARE_OPERATORS_FOR_FLAGS">Q_DECLARE_OPERATORS_FOR_FLAGS</a></b> ( <i>Flags</i> )</td></tr>
</table>
<a name="details"></a>
<hr />
<h2>Detailed Description</h2>
<p>The QFlags class provides a type-safe way of storing OR-combinations of enum values.</p>
<p>The QFlags<Enum> class is a template class, where Enum is an enum type. QFlags is used throughout Qt for storing combinations of enum values.</p>
<p>The traditional C++ approach for storing OR-combinations of enum values is to use an <tt>int</tt> or <tt>uint</tt> variable. The inconvenience with this approach is that there's no type checking at all; any enum value can be OR'd with any other enum value and passed on to a function that takes an <tt>int</tt> or <tt>uint</tt>.</p>
<p>Qt uses QFlags to provide type safety. For example, the <a href="qt.html#AlignmentFlag-enum">Qt::Alignment</a> type is simply a typedef for QFlags<<a href="qt.html#AlignmentFlag-enum">Qt::AlignmentFlag</a>>. <a href="qlabel.html#alignment-prop">QLabel::setAlignment</a>() takes a <a href="qt.html#AlignmentFlag-enum">Qt::Alignment</a> parameter, which means that any combination of <a href="qt.html#AlignmentFlag-enum">Qt::AlignmentFlag</a> values,or 0, is legal:</p>
<pre> label->setAlignment(Qt::AlignLeft | Qt::AlignTop);</pre>
<p>If you try to pass a value from another enum or just a plain integer other than 0, the compiler will report an error. If you need to cast integer values to flags in a untyped fashion, you can use the explicit QFlags constructor as cast operator.</p>
<p>If you want to use QFlags for your own enum types, use the <a href="qflags.html#Q_DECLARE_FLAGS">Q_DECLARE_FLAGS</a>() and <a href="qflags.html#Q_DECLARE_OPERATORS_FOR_FLAGS">Q_DECLARE_OPERATORS_FOR_FLAGS</a>().</p>
<p>Example:</p>
<pre> class MyClass
{
public:
enum Option {
NoOptions = 0x0,
ShowTabs = 0x1,
ShowAll = 0x2,
SqueezeBlank = 0x4
};
Q_DECLARE_FLAGS(Options, Option)
...
};
Q_DECLARE_OPERATORS_FOR_FLAGS(MyClass::Options)</pre>
<p>You can then use the <tt>MyClass::Options</tt> type to store combinations of <tt>MyClass::Option</tt> values.</p>
<a name="flags-and-the-meta-object-system"></a>
<h3>Flags and the Meta-Object System</h3>
<p>The <a href="qflags.html#Q_DECLARE_FLAGS">Q_DECLARE_FLAGS</a>() macro does not expose the flags to the meta-object system, so they cannot be used by Qt Script or edited in Qt Designer. To make the flags available for these purposes, the <a href="qobject.html#Q_FLAGS">Q_FLAGS</a>() macro must be used:</p>
<pre> Q_FLAGS(Options)</pre>
<a name="naming-convention"></a>
<h3>Naming Convention</h3>
<p>A sensible naming convention for enum types and associated QFlags types is to give a singular name to the enum type (e.g., <tt>Option</tt>) and a plural name to the QFlags type (e.g., <tt>Options</tt>). When a singular name is desired for the QFlags type (e.g., <tt>Alignment</tt>), you can use <tt>Flag</tt> as the suffix for the enum type (e.g., <tt>AlignmentFlag</tt>).</p>
<p>See also <a href="qflag.html">QFlag</a>.</p>
<hr />
<h2>Member Type Documentation</h2>
<a name="//apple_ref/cpp/tdef/QFlags/enum_type"></a>
<h3 class="fn"><a name="enum_type-typedef"></a>typedef QFlags::enum_type</h3>
<p>Typedef for the Enum template type.</p>
<hr />
<h2>Member Function Documentation</h2>
<a name="//apple_ref/cpp/instm/QFlags/QFlags"></a>
<h3 class="fn"><a name="QFlags"></a>QFlags::QFlags ( const QFlags & <i>other</i> )</h3>
<p>Constructs a copy of <i>other</i>.</p>
<h3 class="fn"><a name="QFlags-2"></a>QFlags::QFlags ( Enum <i>flag</i> )</h3>
<p>Constructs a <a href="qflags.html">QFlags</a> object storing the given <i>flag</i>.</p>
<h3 class="fn"><a name="QFlags-3"></a>QFlags::QFlags ( Zero <i>zero</i> = 0 )</h3>
<p>Constructs a <a href="qflags.html">QFlags</a> object with no flags set. <i>zero</i> must be a literal 0 value.</p>
<h3 class="fn"><a name="QFlags-4"></a>QFlags::QFlags ( <a href="qflag.html">QFlag</a> <i>value</i> )</h3>
<p>Constructs a <a href="qflags.html">QFlags</a> object initialized with the given integer <i>value</i>.</p>
<p>The <a href="qflag.html">QFlag</a> type is a helper type. By using it here instead of <tt>int</tt>, we effectively ensure that arbitrary enum values cannot be cast to a <a href="qflags.html">QFlags</a>, whereas untyped enum values (i.e., <tt>int</tt> values) can.</p>
<a name="//apple_ref/cpp/instm/QFlags/testFlag"></a>
<h3 class="fn"><a name="testFlag"></a>bool QFlags::testFlag ( Enum <i>flag</i> ) const</h3>
<p>Returns true if the <i>flag</i> is set, otherwise false.</p>
<p>This function was introduced in Qt 4.2.</p>
<a name="//apple_ref/cpp/instm/QFlags/operator int"></a>
<h3 class="fn"><a name="operator-int"></a>QFlags::operator int () const</h3>
<p>Returns the value stored in the <a href="qflags.html">QFlags</a> object as an integer.</p>
<a name="//apple_ref/cpp/instm/QFlags/operator!"></a>
<h3 class="fn"><a name="operator-not"></a>bool QFlags::operator! () const</h3>
<p>Returns true if no flag is set (i.e., if the value stored by the <a href="qflags.html">QFlags</a> object is 0); otherwise returns false.</p>
<a name="//apple_ref/cpp/instm/QFlags/operator&"></a>
<h3 class="fn"><a name="operator-and"></a>QFlags QFlags::operator& ( int <i>mask</i> ) const</h3>
<p>Returns a <a href="qflags.html">QFlags</a> object containing the result of the bitwise AND operation on this object and <i>mask</i>.</p>
<p>See also <a href="qflags.html#operator-and-eq">operator&=</a>(), <a href="qflags.html#operator-7c">operator|</a>(), <a href="qflags.html#operator-5e">operator^</a>(), and <a href="qflags.html#operator-7e">operator~</a>().</p>
<h3 class="fn"><a name="operator-and-2"></a>QFlags QFlags::operator& ( <a href="qtglobal.html#uint-typedef">uint</a> <i>mask</i> ) const</h3>
<p>This is an overloaded function.</p>
<h3 class="fn"><a name="operator-and-3"></a>QFlags QFlags::operator& ( Enum <i>mask</i> ) const</h3>
<p>This is an overloaded function.</p>
<a name="//apple_ref/cpp/instm/QFlags/operator&="></a>
<h3 class="fn"><a name="operator-and-eq"></a>QFlags & QFlags::operator&= ( int <i>mask</i> )</h3>
<p>Performs a bitwise AND operation with <i>mask</i> and stores the result in this <a href="qflags.html">QFlags</a> object. Returns a reference to this object.</p>
<p>See also <a href="qflags.html#operator-and">operator&</a>(), <a href="qflags.html#operator-7c-eq">operator|=</a>(), and <a href="qflags.html#operator-5e-eq">operator^=</a>().</p>
<h3 class="fn"><a name="operator-and-eq-2"></a>QFlags & QFlags::operator&= ( <a href="qtglobal.html#uint-typedef">uint</a> <i>mask</i> )</h3>
<p>This is an overloaded function.</p>
<a name="//apple_ref/cpp/instm/QFlags/operator="></a>
<h3 class="fn"><a name="operator-eq"></a>QFlags & QFlags::operator= ( const QFlags & <i>other</i> )</h3>
<p>Assigns <i>other</i> to this object and returns a reference to this object.</p>
<a name="//apple_ref/cpp/instm/QFlags/operator^"></a>
<h3 class="fn"><a name="operator-5e"></a>QFlags QFlags::operator^ ( QFlags <i>other</i> ) const</h3>
<p>Returns a <a href="qflags.html">QFlags</a> object containing the result of the bitwise XOR operation on this object and <i>other</i>.</p>
<p>See also <a href="qflags.html#operator-5e-eq">operator^=</a>(), <a href="qflags.html#operator-and">operator&</a>(), <a href="qflags.html#operator-7c">operator|</a>(), and <a href="qflags.html#operator-7e">operator~</a>().</p>
<h3 class="fn"><a name="operator-5e-2"></a>QFlags QFlags::operator^ ( Enum <i>other</i> ) const</h3>
<p>This is an overloaded function.</p>
<a name="//apple_ref/cpp/instm/QFlags/operator^="></a>
<h3 class="fn"><a name="operator-5e-eq"></a>QFlags & QFlags::operator^= ( QFlags <i>other</i> )</h3>
<p>Performs a bitwise XOR operation with <i>other</i> and stores the result in this <a href="qflags.html">QFlags</a> object. Returns a reference to this object.</p>
<p>See also <a href="qflags.html#operator-5e">operator^</a>(), <a href="qflags.html#operator-and-eq">operator&=</a>(), and <a href="qflags.html#operator-7c-eq">operator|=</a>().</p>
<h3 class="fn"><a name="operator-5e-eq-2"></a>QFlags & QFlags::operator^= ( Enum <i>other</i> )</h3>
<p>This is an overloaded function.</p>
<a name="//apple_ref/cpp/instm/QFlags/operator|"></a>
<h3 class="fn"><a name="operator-7c"></a>QFlags QFlags::operator| ( QFlags <i>other</i> ) const</h3>
<p>Returns a <a href="qflags.html">QFlags</a> object containing the result of the bitwise OR operation on this object and <i>other</i>.</p>
<p>See also <a href="qflags.html#operator-7c-eq">operator|=</a>(), <a href="qflags.html#operator-5e">operator^</a>(), <a href="qflags.html#operator-and">operator&</a>(), and <a href="qflags.html#operator-7e">operator~</a>().</p>
<h3 class="fn"><a name="operator-7c-2"></a>QFlags QFlags::operator| ( Enum <i>other</i> ) const</h3>
<p>This is an overloaded function.</p>
<a name="//apple_ref/cpp/instm/QFlags/operator|="></a>
<h3 class="fn"><a name="operator-7c-eq"></a>QFlags & QFlags::operator|= ( QFlags <i>other</i> )</h3>
<p>Performs a bitwise OR operation with <i>other</i> and stores the result in this <a href="qflags.html">QFlags</a> object. Returns a reference to this object.</p>
<p>See also <a href="qflags.html#operator-7c">operator|</a>(), <a href="qflags.html#operator-and-eq">operator&=</a>(), and <a href="qflags.html#operator-5e-eq">operator^=</a>().</p>
<h3 class="fn"><a name="operator-7c-eq-2"></a>QFlags & QFlags::operator|= ( Enum <i>other</i> )</h3>
<p>This is an overloaded function.</p>
<a name="//apple_ref/cpp/instm/QFlags/operator~"></a>
<h3 class="fn"><a name="operator-7e"></a>QFlags QFlags::operator~ () const</h3>
<p>Returns a <a href="qflags.html">QFlags</a> object that contains the bitwise negation of this object.</p>
<p>See also <a href="qflags.html#operator-and">operator&</a>(), <a href="qflags.html#operator-7c">operator|</a>(), and <a href="qflags.html#operator-5e">operator^</a>().</p>
<hr />
<h2>Macro Documentation</h2>
<a name="//apple_ref/cpp/macro//Q_DECLARE_FLAGS"></a>
<h3 class="fn"><a name="Q_DECLARE_FLAGS"></a>Q_DECLARE_FLAGS ( <i>Flags</i>, <i>Enum</i> )</h3>
<p>The Q_DECLARE_FLAGS() macro expands to</p>
<pre> typedef QFlags<Enum> Flags;</pre>
<p><i>Enum</i> is the name of an existing enum type, whereas <i>Flags</i> is the name of the <a href="qflags.html">QFlags</a><<i>Enum</i>> typedef.</p>
<p>See the <a href="qflags.html">QFlags</a> documentation for details.</p>
<p>See also <a href="qflags.html#Q_DECLARE_OPERATORS_FOR_FLAGS">Q_DECLARE_OPERATORS_FOR_FLAGS</a>().</p>
<a name="//apple_ref/cpp/macro//Q_DECLARE_OPERATORS_FOR_FLAGS"></a>
<h3 class="fn"><a name="Q_DECLARE_OPERATORS_FOR_FLAGS"></a>Q_DECLARE_OPERATORS_FOR_FLAGS ( <i>Flags</i> )</h3>
<p>The Q_DECLARE_OPERATORS_FOR_FLAGS() macro declares global <tt>operator|()</tt> functions for <i>Flags</i>, which is of type <a href="qflags.html">QFlags</a><T>.</p>
<p>See the <a href="qflags.html">QFlags</a> documentation for details.</p>
<p>See also <a href="qflags.html#Q_DECLARE_FLAGS">Q_DECLARE_FLAGS</a>().</p>
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