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| author | Timothy Pearson <kb9vqf@pearsoncomputing.net> | 2011-11-08 12:31:36 -0600 |
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| committer | Timothy Pearson <kb9vqf@pearsoncomputing.net> | 2011-11-08 12:31:36 -0600 |
| commit | d796c9dd933ab96ec83b9a634feedd5d32e1ba3f (patch) | |
| tree | 6e3dcca4f77e20ec8966c666aac7c35bd4704053 /doc/html/qpixmapcache.html | |
| download | tqt3-d796c9dd933ab96ec83b9a634feedd5d32e1ba3f.tar.gz tqt3-d796c9dd933ab96ec83b9a634feedd5d32e1ba3f.zip | |
Test conversion to TQt3 from Qt3 8c6fc1f8e35fd264dd01c582ca5e7549b32ab731
Diffstat (limited to 'doc/html/qpixmapcache.html')
| -rw-r--r-- | doc/html/qpixmapcache.html | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/doc/html/qpixmapcache.html b/doc/html/qpixmapcache.html new file mode 100644 index 000000000..d3a56da02 --- /dev/null +++ b/doc/html/qpixmapcache.html @@ -0,0 +1,191 @@ +<!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/src/kernel/qpixmapcache.cpp:45 --> +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> +<title>TQPixmapCache Class</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>TQPixmapCache Class Reference</h1> + +<p>The TQPixmapCache class provides an application-global cache for +pixmaps. +<a href="#details">More...</a> +<p><tt>#include <<a href="qpixmapcache-h.html">qpixmapcache.h</a>></tt> +<p><a href="qpixmapcache-members.html">List of all member functions.</a> +<h2>Static Public Members</h2> +<ul> +<li class=fn>int <a href="#cacheLimit"><b>cacheLimit</b></a> ()</li> +<li class=fn>void <a href="#setCacheLimit"><b>setCacheLimit</b></a> ( int n )</li> +<li class=fn>TQPixmap * <a href="#find"><b>find</b></a> ( const TQString & key )</li> +<li class=fn>bool <a href="#find-2"><b>find</b></a> ( const TQString & key, TQPixmap & pm )</li> +<li class=fn>bool insert ( const TQString & key, TQPixmap * pm ) <em>(obsolete)</em></li> +<li class=fn>bool <a href="#insert"><b>insert</b></a> ( const TQString & key, const TQPixmap & pm )</li> +<li class=fn>void <a href="#remove"><b>remove</b></a> ( const TQString & key )</li> +<li class=fn>void <a href="#clear"><b>clear</b></a> ()</li> +</ul> +<hr><a name="details"></a><h2>Detailed Description</h2> + + +<p> The TQPixmapCache class provides an application-global cache for +pixmaps. +<p> + + +<p> This class is a tool for optimized drawing with <a href="qpixmap.html">TQPixmap</a>. You can +use it to store temporary pixmaps that are expensive to generate +without using more storage space than <a href="#cacheLimit">cacheLimit</a>(). Use <a href="#insert">insert</a>() +to insert pixmaps, <a href="#find">find</a>() to find them and <a href="#clear">clear</a>() to empty the +cache. +<p> For example, <a href="qradiobutton.html">TQRadioButton</a> has a non-trivial visual representation +so we don't want to regenerate a pixmap whenever a radio button is +displayed or changes state. In the function +<a href="qbutton.html#drawButton">TQRadioButton::drawButton</a>(), we do not draw the radio button +directly. Instead, we first check the global pixmap cache for a +pixmap with the key "$qt_radio_nnn_", where <tt>nnn</tt> is a numerical +value that specifies the the radio button state. If a pixmap is +found, we <a href="qimage.html#bitBlt">bitBlt</a>() it onto the widget and return. Otherwise, we +create a new pixmap, draw the radio button in the pixmap, and +finally insert the pixmap in the global pixmap cache, using the +key above. The bitBlt() is ten times faster than drawing the +radio button. All radio buttons in the program share the cached +pixmap since TQPixmapCache is application-global. +<p> TQPixmapCache contains no member data, only static functions to +access the global pixmap cache. It creates an internal <a href="qcache.html">TQCache</a> for +caching the pixmaps. +<p> The cache associates a pixmap with a string (key). If two pixmaps +are inserted into the cache using equal keys, then the last pixmap +will hide the first pixmap. The <a href="qdict.html">TQDict</a> and TQCache classes do +exactly the same. +<p> The cache becomes full when the total size of all pixmaps in the +cache exceeds <a href="#cacheLimit">cacheLimit</a>(). The initial cache limit is 1024 KByte +(1 MByte); it is changed with <a href="#setCacheLimit">setCacheLimit</a>(). A pixmap takes +roughly width*height*depth/8 bytes of memory. +<p> See the <a href="qcache.html">TQCache</a> documentation for more details about the cache +mechanism. +<p>See also <a href="environment.html">Environment Classes</a>, <a href="graphics.html">Graphics Classes</a>, and <a href="images.html">Image Processing Classes</a>. + +<hr><h2>Member Function Documentation</h2> +<h3 class=fn>int <a name="cacheLimit"></a>TQPixmapCache::cacheLimit ()<tt> [static]</tt> +</h3> +Returns the cache limit (in kilobytes). +<p> The default setting is 1024 kilobytes. +<p> <p>See also <a href="#setCacheLimit">setCacheLimit</a>(). + +<h3 class=fn>void <a name="clear"></a>TQPixmapCache::clear ()<tt> [static]</tt> +</h3> +Removes all pixmaps from the cache. + +<h3 class=fn><a href="qpixmap.html">TQPixmap</a> * <a name="find"></a>TQPixmapCache::find ( const <a href="qstring.html">TQString</a> & key )<tt> [static]</tt> +</h3> +Returns the pixmap associated with the <em>key</em> in the cache, or +null if there is no such pixmap. +<p> <b>Warning:</b> If valid, you should copy the pixmap immediately (this is +fast). Subsequent insertions into the cache could cause the +pointer to become invalid. For this reason, we recommend you use +<a href="#find">find</a>(const <a href="qstring.html">TQString</a>&, <a href="qpixmap.html">TQPixmap</a>&) instead. +<p> Example: +<pre> + <a href="qpixmap.html">TQPixmap</a>* pp; + <a href="qpixmap.html">TQPixmap</a> p; + if ( (pp=TQPixmapCache::<a href="#find">find</a>("my_big_image", pm)) ) { + p = *pp; + } else { + p.<a href="qpixmap.html#load">load</a>("bigimage.png"); + TQPixmapCache::<a href="#insert">insert</a>("my_big_image", new <a href="qpixmap.html">TQPixmap</a>(p)); + } + painter->drawPixmap(0, 0, p); + </pre> + + +<h3 class=fn>bool <a name="find-2"></a>TQPixmapCache::find ( const <a href="qstring.html">TQString</a> & key, <a href="qpixmap.html">TQPixmap</a> & pm )<tt> [static]</tt> +</h3> +This is an overloaded member function, provided for convenience. It behaves essentially like the above function. +<p> Looks for a cached pixmap associated with the <em>key</em> in the cache. +If a pixmap is found, the function sets <em>pm</em> to that pixmap and +returns TRUE; otherwise leaves <em>pm</em> alone and returns FALSE. +<p> Example: +<pre> + <a href="qpixmap.html">TQPixmap</a> p; + if ( !TQPixmapCache::find("my_big_image", pm) ) { + pm.load("bigimage.png"); + TQPixmapCache::<a href="#insert">insert</a>("my_big_image", pm); + } + painter->drawPixmap(0, 0, p); + </pre> + + +<h3 class=fn>bool <a name="insert"></a>TQPixmapCache::insert ( const <a href="qstring.html">TQString</a> & key, const <a href="qpixmap.html">TQPixmap</a> & pm )<tt> [static]</tt> +</h3> +Inserts a copy of the pixmap <em>pm</em> associated with the <em>key</em> into +the cache. +<p> All pixmaps inserted by the TQt library have a key starting with +"$qt", so your own pixmap keys should never begin "$qt". +<p> When a pixmap is inserted and the cache is about to exceed its +limit, it removes pixmaps until there is enough room for the +pixmap to be inserted. +<p> The oldest pixmaps (least recently accessed in the cache) are +deleted when more space is needed. +<p> <p>See also <a href="#setCacheLimit">setCacheLimit</a>(). + +<h3 class=fn>bool <a name="insert-2"></a>TQPixmapCache::insert ( const <a href="qstring.html">TQString</a> & key, <a href="qpixmap.html">TQPixmap</a> * pm )<tt> [static]</tt> +</h3> +<b>This function is obsolete.</b> It is provided to keep old source working. We strongly advise against using it in new code. +<p> Inserts the pixmap <em>pm</em> associated with <em>key</em> into the cache. +Returns TRUE if successful, or FALSE if the pixmap is too big for the cache. +<p> <strong> +Note: <em>pm</em> must be allocated on the heap (using <tt>new</tt>). +<p> If this function returns FALSE, you must delete <em>pm</em> yourself. +<p> If this function returns TRUE, do not use <em>pm</em> afterwards or +keep references to it because any other insertions into the cache, +whether from anywhere in the application or within TQt itself, could cause +the pixmap to be discarded from the cache and the pointer to +become invalid. +<p> Due to these dangers, we strongly recommend that you use +<a href="#insert">insert</a>(const <a href="qstring.html">TQString</a>&, const <a href="qpixmap.html">TQPixmap</a>&) instead. +</strong> + +<h3 class=fn>void <a name="remove"></a>TQPixmapCache::remove ( const <a href="qstring.html">TQString</a> & key )<tt> [static]</tt> +</h3> +Removes the pixmap associated with <em>key</em> from the cache. + +<h3 class=fn>void <a name="setCacheLimit"></a>TQPixmapCache::setCacheLimit ( int n )<tt> [static]</tt> +</h3> +Sets the cache limit to <em>n</em> kilobytes. +<p> The default setting is 1024 kilobytes. +<p> <p>See also <a href="#cacheLimit">cacheLimit</a>(). + +<!-- eof --> +<hr><p> +This file is part of the <a href="index.html">TQt toolkit</a>. +Copyright © 1995-2007 +<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<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>TQt 3.3.8</div> +</table></div></address></body> +</html> |