304 lines
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304 lines
12 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xlink="http://www.w3.org/1999/xlink">
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<head>
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<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
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<title>Performance</title>
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<link href="style.css" rel="stylesheet" type="text/css">
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<link href="prettify.css" type="text/css" rel="stylesheet">
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<script type="text/javascript" src="prettify.js"></script><script type="text/javascript" src="lang-vb.js"></script><link href="../resources/main.css" media="screen" rel="stylesheet" type="text/css">
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</head>
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<body onload="prettyPrint()"><div class="placing">
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<br><table class="navigation"><tr>
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<td class="navigation-previous"><a href="chapter-owner-draw.html"><strong>
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« Owner Drawing</strong></a></td>
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<td class="navigation-index"><a href="../../../quick-start-guide/better-listview/index.html"><strong>Index</strong></a></td>
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<td class="navigation-next"><a href="chapter-save-load.html"><strong>Saving and Loading ListView Content »
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</strong></a></td>
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</tr></table>
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<br><h1>Performance</h1>
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<div class="banner">
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<a href="../../../blog/page/6/index.html"><img src="../resources/overview.gif" alt="Better ListView" class="ss"></a>
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<div class="inside">
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<div class="text">Better ListView: Ultimate .NET ListView replacement control for WinForms (C#, VB.NET)</div>
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<span class="dbtn-c dbtn-hilight"><span class="dbtn-w"><a href="../../../betterlistview.exe" class="dbtn">Download</a></span></span>
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<span class="dbtn-c"><span class="dbtn-w"><a href="../../../blog/page/6/index.html" class="dbtn">More Info</a></span></span>
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</div>
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</div>
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<h2>
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<a name="beginupdate-endupdate" id="beginupdate-endupdate"></a>Using BeginUpdate and
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EndUpdate</h2>
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<p>When doing several operations with Better ListView at a time, these
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operations should be enclosed in BeginUpdate and EndUpdate method
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calls.</p>
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<p>For example:</p>
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<p><strong>C#</strong></p>
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<pre class="prettyprint"><code class="lang-cs">listView.BeginUpdate();
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for (int i = 0; i < 100; i++)
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{
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listView.Items.Add(String.Format("Item no. {0}", i));
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}
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listView.EndUpdate();</code></pre>
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<p><strong>Visual Basic</strong></p>
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<pre class="prettyprint"><code class="lang-vb">ListView.BeginUpdate()
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For i As Integer = 0 To 99
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ListView.Items.Add([String].Format("Item no. {0}", i))
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Next
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listView.EndUpdate()</code></pre>
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<p>Without these methods, Better ListView would refresh itself 100
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times and the whole operation would take noticeable time. The same applies
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to setting properties or modifying other collections (column headers,
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sub-items, child items, groups) so it is still convenient to use
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<span class="code">BeginUpdate</span> and <span class="code">EndUpdate</span> when setting multiple
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properties:</p>
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<p><strong>C#</strong></p>
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<pre class="prettyprint"><code class="lang-cs">BeginUpdate();
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listView.Items[0].SubItems[1].Align = TextAlignment.Right;
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listView.MultiSelect = true;
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listView.CheckBoxes = BetterListViewCheckBoxes.TwoState;
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EndUpdate();</code></pre>
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<p><strong>Visual Basic</strong></p>
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<pre class="prettyprint"><code class="lang-vb">BeginUpdate()
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ListView.Items(0).SubItems(1).Align = TextAlignment.Right
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ListView.MultiSelect = True
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ListView.CheckBoxes = BetterListViewCheckBoxes.TwoState
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EndUpdate()</code></pre>
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<p>There can be multiple calls of <span class="code">BeginUpdate</span> and the
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control will actually refresh after the same number of
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<span class="code">EndUpdate</span> calls are made.</p>
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<p>It is also possible to call <span class="code">EndUpdate</span> with boolean
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parameter. The call <span class="code">EndUpdate(true)</span> will avoid refreshing the
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control, but still move the control out of the updation state.</p>
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<p>To check whether the control is in updation state, use the
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<span class="code">IsUpdating</span> property:</p>
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<p><strong>C#</strong></p>
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<pre class="prettyprint"><code class="lang-cs">// intentionally call BeginUpdate twice
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BeginUpdate();
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BeginUpdate();
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// listView.IsUpdating is true
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EndUpdate();
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// still updating, listView.IsUpdating is true
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EndUpdate();
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// still updating, listView.IsUpdating is false</code></pre>
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<p><strong>Visual Basic</strong></p>
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<pre class="prettyprint"><code class="lang-vb">' intentionally call BeginUpdate twice
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BeginUpdate()
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BeginUpdate()
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' listView.IsUpdating is true
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EndUpdate()
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' still updating, listView.IsUpdating is true
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EndUpdate()
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' still updating, listView.IsUpdating is false</code></pre>
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<h2>Performance of Image versus ImageList</h2>
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<p>There are two ways of setting images to Better ListView elements:
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<span class="code">Image</span> property and <span class="code">ImageList</span> property.</p>
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<p><span class="code">ImageList</span> is convenient when you want to use images
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which are not attached directly to elements (the element - e.g. item -
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only refers to image index or key within the global image list). The
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performance of <span class="code">ImageList</span>, however, is quite slow. The
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slowness can be painful in some critical cases, like column
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resizing.</p>
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<p>When working with many items, we recommend using <span class="code">Image</span>
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property instead.</p>
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<h2>Performance Properties</h2>
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<p>Better ListView was designed to be responsive to user although it is
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quite complex control. It is sometimes convenient to adjust optimization
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settings. This can be done through the following properties:</p>
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<ul style="list-style:none">
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<li>
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<span class="code">BetterListView.AutoSizeItemsInDetailsView</span><ul style="list-style:none"><li>
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<p><span class="code">false</span> by default</p>
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</li></ul>
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</li>
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<li>
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<span class="code">BetterListView.CacheImages</span><ul style="list-style:none"><li>
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<p><span class="code">true</span> by default</p>
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</li></ul>
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</li>
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<li>
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<span class="code">BetterListView.MaximumToolTipTextLength</span><ul style="list-style:none"><li>
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<p><span class="code">1000</span> by default</p>
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</li></ul>
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</li>
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<li>
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<span class="code">BetterListView.OptimizedInvalidation</span><ul style="list-style:none"><li>
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<p><span class="code">true</span> by default</p>
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</li></ul>
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</li>
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<li>
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<span class="code">BetterListViewColumnHeader.SmoothColumnResize</span><ul style="list-style:none"><li>
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<p><span class="code">true</span> by default. Can be set on each column header
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separately.</p>
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</li></ul>
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</li>
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<li>
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<span class="code">BetterListView.SortOnCollectionChange</span><ul style="list-style:none"><li>
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<p><span class="code">true</span> by default</p>
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</li></ul>
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</li>
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</ul>
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<h2>Automatic Resizing of Items in Details View</h2>
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<p>Better ListView supports displaying items in
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<strong><em>Details</em></strong> view even when there are no columns. When
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columns are displayed, item width is determined by the total width of all
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columns. When columns are not present, items have fixed width by default.
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By settings <span class="code">AutoSizeItemsInDetailsView</span> property to
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<span class="code">true</span>, items will be always stretched to client area width.
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The following images shows item size without and with automatic
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resizing:</p>
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<p class="images"><img src="performance-autosizeitemsindetailsview1.png"></p>
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<p class="images"><img src="performance-autosizeitemsindetailsview2.png"></p>
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<p>Items are not resized by default, because it slows performance when
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Better ListView contains huge number of items.</p>
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<h2>Image Caching</h2>
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<p>When Better ListView contains images of various sizes which are
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possibly downscaled, its performance can drop. Showing image frames and
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shadows can slow down redrawing of the control even more. When
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<span class="code">CacheImages</span> property is set to <span class="code">true</span>, Better
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ListView downscales every image just once and then stores the scaled image
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(also with its frame) to internal cache. The scaled image is then
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displayed quickly.</p>
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<p>The cache is cleared whenever an item property si changed affecting
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image or its border.</p>
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<h2>Optimized Invalidation</h2>
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<p>When user moves mouse cursor over the control, not all the elements
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have to be redrawn. For example, when user moves mouse cursor from column
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header A to item B, hot state of these elements changes and only these two
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elements are be redrawn. Optimized invalidation finds always the smallest
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region to redraw.</p>
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<p>This behavior is used when <span class="code">OptimizedInvalidation</span>
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property is set to <span class="code">true</span>. This behavior can be sometimes
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unwanted, e.g. on some specific <strong><em><a href="chapter-owner-draw.html">Owner drawing</a></em></strong>.</p>
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<h2>Smooth Column Resizing</h2>
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<p>When columns are resized in <strong><em>Details</em></strong> view, the
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items and sub-items are resized as well. Item resizing may pose a
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performance bottleneck, when there are huge number of items present and
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column resizing animation may not be smooth. It is possible to set
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<span class="code">BetterListViewColumnHeader.SmoothColumnResize</span> property to
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<span class="code">false</span>, which will cause items and sub-items in the specific
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column to be resized only once: when column resizing is finished (e.g.
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when user releases mouse button).</p>
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<p>When the smooth column resizing feature is turned off, a line is
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displayed that shows new column width:</p>
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<p class="images"><img src="performance-smoothcolumnresize.png"></p>
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<h2>Sorting on Collection Change</h2>
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<p>When the Better ListView is sorted and its content is changed, it
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keeps sort order by default. This needs, however, to re-sort all the items
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whenever there is some change.</p>
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<p>This behavior can be turned off by settings
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<span class="code">SortOnCollectionChanged</span> property to <span class="code">false</span>. In
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that case, Better ListView does not guarantee that the Items collection is
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always sorted and you have to perform sorting manually, when
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needed.</p>
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<h2>Maximum ToolTip Text Length</h2>
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<p>The property <span class="code">MaximumToolTipTextLength</span> limits the
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maximum allowed length of text within automatic tooltips. When element
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text is very long, it may take a long time for a tooltip to
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display.</p>
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<p>When the element text is too long, it is shortened to length of
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(<span class="code">MaximumToolTipTextLength - 1</span>) and an ellipsis character is
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added at the end of the text.</p>
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<br><div class="banner">
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<a href="../../../blog/page/6/index.html"><img src="../resources/overview.gif" alt="Better ListView" class="ss"></a>
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||
<div class="inside">
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||
<div class="text">Better ListView: Ultimate .NET ListView replacement control for WinForms (C#, VB.NET)</div>
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<span class="dbtn-c dbtn-hilight"><span class="dbtn-w"><a href="../../../betterlistview.exe" class="dbtn">Download</a></span></span>
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<span class="dbtn-c"><span class="dbtn-w"><a href="../../../blog/page/6/index.html" class="dbtn">More Info</a></span></span>
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</div>
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</div>
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<table class="navigation"><tr>
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<td class="navigation-previous"><a href="chapter-owner-draw.html"><strong>
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« Owner Drawing</strong></a></td>
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<td class="navigation-index"><a href="../../../quick-start-guide/better-listview/index.html"><strong>Index</strong></a></td>
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<td class="navigation-next"><a href="chapter-save-load.html"><strong>Saving and Loading ListView Content »
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</strong></a></td>
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</tr></table>
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<br><table class="footer"><tr>
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<td class="footer-title">Better ListView Documentation
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</td>
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<td class="footer-copyright">
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Copyright © 2010-2012 <a href="../../../index.html" target="_blank">ComponentOwl.com</a>
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</td>
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</tr></table>
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</div></body>
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</html>
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