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diff --git a/doc/html/geometry.html b/doc/html/geometry.html new file mode 100644 index 0000000..6b86e56 --- /dev/null +++ b/doc/html/geometry.html @@ -0,0 +1,122 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> +<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/doc/misc.doc:1031 --> +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> +<title>Window Geometry</title> +<style type="text/css"><!-- +fn { margin-left: 1cm; text-indent: -1cm; } +a:link { color: #004faf; text-decoration: none } +a:visited { color: #672967; text-decoration: none } +body { background: #ffffff; color: black; } +--></style> +</head> +<body> + +<table border="0" cellpadding="0" cellspacing="0" width="100%"> +<tr bgcolor="#E5E5E5"> +<td 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="mainclasses.html"> +<font color="#004faf">Main Classes</font></a> + | <a href="annotated.html"> +<font color="#004faf">Annotated</font></a> + | <a href="groups.html"> +<font color="#004faf">Grouped Classes</font></a> + | <a href="functions.html"> +<font color="#004faf">Functions</font></a> +</td> +<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Window Geometry</h1> + + +<h2> Overview +</h2> +<a name="1"></a><p> <a href="qwidget.html">QWidget</a> provides several functions that deal with a widget's +geometry. Some of these functions operate on the pure client area +(i.e. the window excluding the window frame), others include the +window frame. The differentiation is done in a way that covers the +most common usage transparently. +<p> <center><table cellpadding="4" cellspacing="2" border="0"> +<tr bgcolor="#f0f0f0"> +<td valign="top"><strong>Including the window frame: +<td valign="top">x(), y(), frameGeometry(), pos() and move() +<tr bgcolor="#d0d0d0"> +<td valign="top"><strong>Excluding the window frame:</strong> +<td valign="top">geometry(), width(), height(), rect() and size() +</table></center> +<p> Note that the distinction only matters for decorated top-level +widgets. For all child widgets, the frame geometry is equal to the +widget's client geometry. +<p> This diagram shows most of the functions in use: +<center><img src="geometry.png" alt="Geometry diagram"></center> +<p> <h2> Unix/X11 peculiarities +</h2> +<a name="2"></a><p> On Unix/X11, a window does not have a frame until the window manager +decorates it. This happens asynchronously at some point in time after +calling show() and the first paint event the window receives: or it +does not happen at all. Bear in mind that X11 is policy-free (others +call it flexible). Thus you cannot make any safe assumption about the +decoration frame your window will get. Basic rule: there's always one +user who uses a window manager that breaks your assumption, and who +will complain to you. +<p> Furthermore, a toolkit cannot simply place windows on the screen. All +Qt can do is to send certain hints to the window manager. The window +manager, a separate process, may either obey, ignore or misunderstand +them. Due to the partially unclear Inter-Client Communication +Conventions Manual (ICCCM), window placement is handled quite +differently in existing window managers. +<p> X11 provides no standard or easy way to get the frame geometry once +the window is decorated. Qt solves this problem with nifty heuristics +and clever code that works on a wide range of window managers that +exist today. Don't be surprised if you find one where frameGeometry() +returns bogus results though. +<p> Nor does X11 provide a way to maximize a window. The showMaximized() +function in Qt therefore has to emulate the feature. Its result +depends on the result of frameGeometry() and the capability of the +window manager to do proper window placement, neither of which can be +guaranteed. +<p> <h2> Restoring a Window's Geometry +</h2> +<a name="3"></a><p> A common task in modern applications is to restore a window's geometry +in a later session. On Windows, this is basically storing the result +of geometry() and calling setGeometry() in the next session before +calling show(). On X11, this won't work because an invisible window +doesn't have a frame yet. The window manager would decorate the window +later. When this happens, the window shifts towards the bottom/right +corner of the screen depending on the size of the decoration frame. X +theoretically provides a way to avoid this shift. Our tests have +shown, though, that almost all window managers fail to implement this +feature. +<p> A workaround is to call setGeometry() after show(). This has the +two disadvantages that the widget appears at a wrong place for a +millisecond (results in flashing) and that currently only every +second window manager gets it right. A safer solution is to store +both pos() and size() and to restore the geometry using resize() and +move() before calling show(), as demonstrated in the following +example: +<p> <pre> + MyWidget* widget = new MyWidget + ... + <a href="qpoint.html">QPoint</a> p = widget->pos(); // store position + <a href="qsize.html">QSize</a> s = widget->size(); // store size + ... + widget = new MyWidget; + widget->resize( s ); // restore size + widget->move( p ); // restore position + widget->show(); // show widget +</pre> + +<p> This method works on both MS-Windows and most existing X11 window +managers. +<p> +<!-- eof --> +<p><address><hr><div align=center> +<table width=100% cellspacing=0 border=0><tr> +<td>Copyright © 2007 +<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a> +<td align=right><div align=right>Qt 3.3.8</div> +</table></div></address></body> +</html> |