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| 2 | <!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/doc/customstyles.doc:36 -->
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| 3 | <html>
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| 4 | <head>
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| 5 | <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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| 6 | <title>Style overview</title>
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| 7 | <style type="text/css"><!--
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| 8 | fn { margin-left: 1cm; text-indent: -1cm; }
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| 9 | a:link { color: #004faf; text-decoration: none }
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| 10 | a:visited { color: #672967; text-decoration: none }
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| 11 | body { background: #ffffff; color: black; }
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| 12 | --></style>
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| 13 | </head>
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| 14 | <body>
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| 15 |
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| 16 | <table border="0" cellpadding="0" cellspacing="0" width="100%">
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| 17 | <tr bgcolor="#E5E5E5">
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| 18 | <td valign=center>
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| 19 | <a href="index.html">
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| 20 | <font color="#004faf">Home</font></a>
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| 21 | | <a href="classes.html">
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| 22 | <font color="#004faf">All Classes</font></a>
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| 23 | | <a href="mainclasses.html">
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| 24 | <font color="#004faf">Main Classes</font></a>
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| 25 | | <a href="annotated.html">
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| 26 | <font color="#004faf">Annotated</font></a>
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| 27 | | <a href="groups.html">
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| 28 | <font color="#004faf">Grouped Classes</font></a>
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| 29 | | <a href="functions.html">
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| 30 | <font color="#004faf">Functions</font></a>
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| 31 | </td>
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| 32 | <td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Style overview</h1>
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| 33 |
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| 34 |
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| 35 |
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| 36 | <p> A style in Qt implements the look and feel found in a GUI for a
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| 37 | particular platform. For example, Windows platforms may use the
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| 38 | Windows or Windows-XP style, Unix platforms may use the <a href="motif-extension.html#Motif">Motif</a> style,
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| 39 | and so on.
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| 40 | <p> This is a short guide that describes the steps that are necessary to
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| 41 | get started creating and using custom styles with the Qt 3.x style
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| 42 | API. First, we go through the steps necessary to create a style:
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| 43 | <ol type=1>
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| 44 | <li> Pick a base style to inherit from.
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| 45 | <li> Re-implement the necessary functions in the derived class.
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| 46 | </ol>
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| 47 | Then we explain how to use the new style from within your own
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| 48 | applications, or as a plugin that can be used by existing Qt
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| 49 | applications.
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| 50 | <p> <h2> Creating a custom style
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| 51 | </h2>
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| 52 | <a name="1"></a><p> <h3> 1. Pick a base style to inherit from.
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| 53 | </h3>
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| 54 | <a name="1-1"></a><p> The first step is to pick one of the base styles provided with Qt to
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| 55 | build your custom style from. The choice will depend on what look and
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| 56 | feel you are trying to achieve. We recommend that you choose from the
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| 57 | <a href="qwindowsstyle.html">QWindowsStyle</a> derived classes or the <a href="qmotifstyle.html">QMotifStyle</a> derived classes.
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| 58 | These are the two base look and feel classes in the Qt style engine.
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| 59 | Inheriting directly from <a href="qcommonstyle.html">QCommonStyle</a> is also an option if you want to
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| 60 | start almost from scratch when implementing your style. In this simple
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| 61 | example we will inherit from QWindowsStyle.
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| 62 | <p> <h3> 2. Re-implement the necessary functions in your derived class.
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| 63 | </h3>
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| 64 | <a name="1-2"></a><p> Depending on which parts of the base style you want to change, you
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| 65 | must re-implement the functions that are used to draw those parts
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| 66 | of the interface. If you take a look at the <a href="qstyle.html">QStyle</a> documentation,
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| 67 | you will find a list of the different primitives, controls and complex
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| 68 | controls. In this example we will first change the look of the
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| 69 | standard arrows that are used in the QWindowsStyle. The arrows are
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| 70 | PrimitiveElements that are drawn by the drawPrimitive() function,
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| 71 | so we need to re-implement that function. We need the following class
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| 72 | declaration:
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| 73 | <p> <pre>
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| 74 | #include <<a href="qwindowsstyle-h.html">qwindowsstyle.h</a>>
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| 75 |
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| 76 | class CustomStyle : public <a href="qwindowsstyle.html">QWindowsStyle</a> {
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| 77 | <a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a>
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| 78 | public:
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| 79 | CustomStyle();
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| 80 | ~CustomStyle();
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| 81 |
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| 82 | void drawPrimitive( PrimitiveElement pe,
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| 83 | <a href="qpainter.html">QPainter</a> *p,
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| 84 | const <a href="qrect.html">QRect</a> & r,
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| 85 | const <a href="qcolorgroup.html">QColorGroup</a> & cg,
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| 86 | SFlags flags = Style_Default,
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| 87 | const <a href="qstyleoption.html">QStyleOption</a> & = QStyleOption::Default ) const;
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| 88 |
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| 89 | private:
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| 90 | // Disabled copy constructor and operator=
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| 91 | CustomStyle( const CustomStyle & );
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| 92 | CustomStyle& operator=( const CustomStyle & );
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| 93 | };
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| 94 | </pre>
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| 95 |
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| 96 | <p> Note that we disable the copy constructor and the '=' operator for our
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| 97 | style. <a href="qobject.html">QObject</a> is the base class for all style classes in Qt, and a
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| 98 | QObject inherently cannot be copied since there are some aspects of it
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| 99 | that are not copyable.
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| 100 | <p> From the <a href="qstyle.html">QStyle</a> docs we see that <tt>PE_ArrowUp</tt>, <tt>PE_ArrowDown</tt>, <tt>PE_ArrowLeft</tt> and <tt>PE_ArrowRight</tt> are the primitives we need to do
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| 101 | something with. We get the following in our drawPrimitive() function:
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| 102 | <p> <pre>
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| 103 | CustomStyle::CustomStyle()
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| 104 | {
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| 105 | }
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| 106 |
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| 107 | CustomStyle::~CustomStyle()
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| 108 | {
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| 109 | }
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| 110 |
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| 111 | void CustomStyle::drawPrimitive( PrimitiveElement pe,
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| 112 | <a href="qpainter.html">QPainter</a> * p,
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| 113 | const <a href="qrect.html">QRect</a> & r,
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| 114 | const <a href="qcolorgroup.html">QColorGroup</a> & cg,
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| 115 | SFlags flags,
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| 116 | const <a href="qstyleoption.html">QStyleOption</a> & opt ) const
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| 117 | {
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| 118 | // we are only interested in the arrows
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| 119 | if (pe >= PE_ArrowUp && pe <= PE_ArrowLeft) {
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| 120 | <a href="qpointarray.html">QPointArray</a> pa( 3 );
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| 121 | // make the arrow cover half the area it is supposed to be
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| 122 | // painted on
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| 123 | int x = r.<a href="qrect.html#x">x</a>();
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| 124 | int y = r.<a href="qrect.html#y">y</a>();
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| 125 | int w = r.<a href="qrect.html#width">width</a>() / 2;
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| 126 | int h = r.<a href="qrect.html#height">height</a>() / 2;
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| 127 | x += (r.<a href="qrect.html#width">width</a>() - w) / 2;
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| 128 | y += (r.<a href="qrect.html#height">height</a>() - h) /2;
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| 129 |
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| 130 | switch( pe ) {
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| 131 | case PE_ArrowDown:
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| 132 | pa.<a href="qpointarray.html#setPoint">setPoint</a>( 0, x, y );
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| 133 | pa.<a href="qpointarray.html#setPoint">setPoint</a>( 1, x + w, y );
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| 134 | pa.<a href="qpointarray.html#setPoint">setPoint</a>( 2, x + w / 2, y + h );
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| 135 | break;
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| 136 | case PE_ArrowUp:
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| 137 | pa.<a href="qpointarray.html#setPoint">setPoint</a>( 0, x, y + h );
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| 138 | pa.<a href="qpointarray.html#setPoint">setPoint</a>( 1, x + w, y + h );
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| 139 | pa.<a href="qpointarray.html#setPoint">setPoint</a>( 2, x + w / 2, y );
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| 140 | break;
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| 141 | case PE_ArrowLeft:
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| 142 | pa.<a href="qpointarray.html#setPoint">setPoint</a>( 0, x + w, y );
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| 143 | pa.<a href="qpointarray.html#setPoint">setPoint</a>( 1, x + w, y + h );
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| 144 | pa.<a href="qpointarray.html#setPoint">setPoint</a>( 2, x, y + h / 2 );
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| 145 | break;
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| 146 | case PE_ArrowRight:
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| 147 | pa.<a href="qpointarray.html#setPoint">setPoint</a>( 0, x, y );
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| 148 | pa.<a href="qpointarray.html#setPoint">setPoint</a>( 1, x, y + h );
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| 149 | pa.<a href="qpointarray.html#setPoint">setPoint</a>( 2, x + w, y + h / 2 );
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| 150 | break;
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| 151 | default: break;
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| 152 |
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| 153 | }
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| 154 |
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| 155 | // use different colors to indicate that the arrow is
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| 156 | // enabled/disabled
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| 157 | if ( flags & Style_Enabled ) {
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| 158 | p-><a href="qpainter.html#setPen">setPen</a>( cg.<a href="qcolorgroup.html#mid">mid</a>() );
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| 159 | p-><a href="qpainter.html#setBrush">setBrush</a>( cg.<a href="qcolorgroup.html#brush">brush</a>( QColorGroup::ButtonText ) );
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| 160 | } else {
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| 161 | p-><a href="qpainter.html#setPen">setPen</a>( cg.<a href="qcolorgroup.html#buttonText">buttonText</a>() );
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| 162 | p-><a href="qpainter.html#setBrush">setBrush</a>( cg.<a href="qcolorgroup.html#brush">brush</a>( QColorGroup::Mid ) );
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| 163 | }
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| 164 | p-><a href="qpainter.html#drawPolygon">drawPolygon</a>( pa );
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| 165 | } else {
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| 166 | // let the base style handle the other primitives
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| 167 | QWindowsStyle::<a href="qstyle.html#drawPrimitive">drawPrimitive</a>( pe, p, r, cg, flags, data );
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| 168 | }
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| 169 | }
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| 170 | </pre>
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| 171 |
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| 172 | <p> <h3> Using a custom style
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| 173 | </h3>
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| 174 | <a name="1-3"></a><p> There are several ways of using a custom style in a Qt application.
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| 175 | The simplest way is to include the following lines of code in the
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| 176 | application's main() function:
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| 177 | <p> <pre>
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| 178 | #include "customstyle.h"
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| 179 |
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| 180 | int main( int argc, char ** argv )
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| 181 | {
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| 182 | QApplication::<a href="qapplication.html#setStyle">setStyle</a>( new CustomStyle() );
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| 183 | // do the usual routine on creating your QApplication object etc.
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| 184 | }
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| 185 | </pre>
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| 186 |
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| 187 | <p> Note that you must also include the <tt>customstyle.h</tt> and <tt>customstyle.cpp</tt> files in your project.
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| 188 | <p> 2. Creating and using a pluggable style
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| 189 | <p> You may want to make your style available for use in other
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| 190 | applications, some of which may not be yours and are not available for
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| 191 | you to recompile. The Qt Plugin system makes it possible to create
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| 192 | styles as plugins. Styles created as plugins are loaded as shared
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| 193 | objects at runtime by Qt itself. Please refer to the <a href="plugins-howto.html">Qt Plugin</a> documentation for more
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| 194 | information on how to go about creating a style plugin.
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| 195 | <p> Compile your plugin and put it into $QTDIR/plugins/styles. We now have
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| 196 | a pluggable style that Qt can load automatically. To use your new
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| 197 | style with existing applications, simply start the application with
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| 198 | the following argument:
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| 199 | <p> <pre>
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| 200 | ./application -style custom
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| 201 | </pre>
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| 202 |
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| 203 | <p> The application will use the look and feel from the custom style you
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| 204 | implemented.
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| 205 | <p>
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| 206 | <!-- eof -->
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| 207 | <p><address><hr><div align=center>
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| 208 | <table width=100% cellspacing=0 border=0><tr>
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| 209 | <td>Copyright © 2007
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| 210 | <a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
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| 211 | <td align=right><div align=right>Qt 3.3.8</div>
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| 212 | </table></div></address></body>
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| 213 | </html>
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