<?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"> <!-- /home/gvatteka/dev/qt-4.3/doc/src/stylesheet.qdoc --> <head> <title>Customizing Qt Widgets Using Style Sheets</title> <link href="classic.css" rel="stylesheet" type="text/css" /> </head> <body> <h1 align="center">Customizing Qt Widgets Using Style Sheets<br /><small></small></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> <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</tt></a>, <a href="stylesheet-reference.html#border-width-prop">border-width</tt></a>, and <a href="stylesheet-reference.html#padding-prop">padding</tt></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</tt></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</tt></a> property. You can use <a href="stylesheet-reference.html#background-repeat-prop">background-repeat</tt></a> and <a href="stylesheet-reference.html#background-origin-prop">background-origin</tt></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 you the <a href="stylesheet-reference.html#border-image-prop">border-image</tt></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</tt></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, it's alignment is specified using the <a href="stylesheet-reference.html#image-position-prop">image-position</tt></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 heirarchy (tree) of subcontrols drawn on top of each other. For example, the <a href="gui/QComboBox.html"><tt>QComboBox</tt></a> draws the drop-down sub-control followed by the down-arrow sub-control. A <a href="gui/QComboBox.html"><tt>QComboBox</tt></a> is thus rendered as follows:</p> <ul> <li>Render the <a href="gui/QComboBox.html"><tt>QComboBox</tt></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="gui/QComboBox.html"><tt>QComboBox</tt></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</tt></a> and <a href="stylesheet-reference.html#subcontrol-origin-prop">subcontrol-origin</tt></a> properties.</p> <p>Once positioned, sub-controls can be styled using the the <a href="stylesheet-customizing.html#box-model">box model</tt></a>.</p> <p /><address><hr /><div align="center"> <table width="100%" cellspacing="0" border="0"><tr class="address"> <td width="30%">Copyright © 2007 <a href="trolltech.html">Trolltech</a></td> <td width="40%" align="center"><a href="trademarks.html">Trademarks</a></td> <td width="30%" align="right"><div align="right">Qt Jambi </div></td> </tr></table></div></address></body> </html>