<?xml version="1.0" encoding="iso-8859-1"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <!-- stylesheet.qdoc --> <head> <title>Qt 4.6: Customizing Qt Widgets Using Style Sheets</title> <link rel="prev" href="stylesheet-designer.html" /> <link rel="contents" href="stylesheet.html" /> <link rel="next" href="stylesheet-reference.html" /> <link href="classic.css" rel="stylesheet" type="text/css" /> </head> <body> <table border="0" cellpadding="0" cellspacing="0" width="100%"> <tr> <td align="left" valign="top" width="32"><a href="http://qt.nokia.com/"><img src="images/qt-logo.png" align="left" border="0" /></a></td> <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><p> [Previous: <a href="stylesheet-designer.html">Qt Designer Integration</a>] [<a href="stylesheet.html">Contents</a>] [Next: <a href="stylesheet-reference.html">Qt Style Sheets Reference</a>] </p> <h1 class="title">Customizing Qt Widgets Using Style Sheets<br /><span class="subtitle"></span> </h1> <p>When using style sheets, every widget is treated as a box with four concentric rectangles: the margin rectangle, the border rectangle, the padding rectangle, and the content rectangle. The box model describes this in further detail.</p> <ul><li><a href="#the-box-model">The Box Model</a></li> <li><a href="#sub-controls">Sub-controls</a></li> </ul> <a name="box-model"></a><a name="the-box-model"></a> <h2>The Box Model</h2> <p>The four concentric rectangles appear conceptually as below:</p> <p align="center"><img src="images/stylesheet-boxmodel.png" /></p><ul> <li>The margin falls outside the border.</li> <li>The border is drawn between the margin and the padding.</li> <li>The padding falls inside the border, between the border and the actual contents.</li> <li>The content is what is left from the original widget or subcontrol once we have removed the margin, the border, and the padding.</li> </ul> <p>The <a href="stylesheet-reference.html#margin-prop">margin</a>, <a href="stylesheet-reference.html#border-width-prop">border-width</a>, and <a href="stylesheet-reference.html#padding-prop">padding</a> properties all default to zero. In that case, all four rectangles (<tt>margin</tt>, <tt>border</tt>, <tt>padding</tt>, and <tt>content</tt>) coincide exactly.</p> <p>You can specify a background for the widget using the <a href="stylesheet-reference.html#background-image-prop">background-image</a> property. By default, the background-image is drawn only for the area inside the border. This can be changed using the <a href="stylesheet-reference.html#background-clip-prop">background-clip</a> property. You can use <a href="stylesheet-reference.html#background-repeat-prop">background-repeat</a> and <a href="stylesheet-reference.html#background-origin-prop">background-origin</a> to control the repetition and origin of the background image.</p> <p>A background-image does not scale with the size of the widget. To provide a "skin" or background that scales along with the widget size, one must use <a href="stylesheet-reference.html#border-image-prop">border-image</a>. Since the border-image property provides an alternate background, it is not required to specify a background-image when border-image is specified. In the case, when both of them are specified, the border-image draws over the background-image.</p> <p>In addition, the <a href="stylesheet-reference.html#image-prop">image</a> property may be used to draw an image over the border-image. The image specified does not tile or stretch and when its size does not match the size of the widget, its alignment is specified using the <a href="stylesheet-reference.html#image-position-prop">image-position</a> property. Unlike background-image and border-image, one may specify a SVG in the image property, in which case the image is scaled automatically according to the widget size.</p> <p>The steps to render a rule are as follows:</p> <ul> <li>Set clip for entire rendering operation (border-radius)</li> <li>Draw the background (background-image)</li> <li>Draw the border (border-image, border)</li> <li>Draw overlay image (image)</li> </ul> <a name="sub-controls"></a><a name="sub-controls"></a> <h2>Sub-controls</h2> <p>A widget is considered as a hierarchy (tree) of subcontrols drawn on top of each other. For example, the <a href="qcombobox.html">QComboBox</a> draws the drop-down sub-control followed by the down-arrow sub-control. A <a href="qcombobox.html">QComboBox</a> is thus rendered as follows:</p> <ul> <li>Render the <a href="qcombobox.html">QComboBox</a> { } rule</li> <li>Render the QComboBox::drop-down { } rule</li> <li>Render the QComboBox::down-arrow { } rule</li> </ul> <p>Sub-controls share a parent-child relationship. In the case of <a href="qcombobox.html">QComboBox</a>, the parent of down-arrow is the drop-down and the parent of drop-down is the widget itself. Sub-controls are positioned within their parent using the <a href="stylesheet-reference.html#subcontrol-position-prop">subcontrol-position</a> and <a href="stylesheet-reference.html#subcontrol-origin-prop">subcontrol-origin</a> properties.</p> <p>Once positioned, sub-controls can be styled using the <a href="#box-model">box model</a>.</p> <p><b>Note:</b> With complex widgets such as <a href="qcombobox.html">QComboBox</a> and <a href="qscrollbar.html">QScrollBar</a>, if one property or sub-control is customized, <b>all</b> the other properties or sub-controls must be customized as well.</p> <p> [Previous: <a href="stylesheet-designer.html">Qt Designer Integration</a>] [<a href="stylesheet.html">Contents</a>] [Next: <a href="stylesheet-reference.html">Qt Style Sheets Reference</a>] </p> <p /><address><hr /><div align="center"> <table width="100%" cellspacing="0" border="0"><tr class="address"> <td width="40%" align="left">Copyright © 2010 Nokia Corporation and/or its subsidiary(-ies)</td> <td width="20%" align="center"><a href="trademarks.html">Trademarks</a></td> <td width="40%" align="right"><div align="right">Qt 4.6.3</div></td> </tr></table></div></address></body> </html>