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POStyling Qt Model/View items based on their ItemDataRole properties
 

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    <p>I have a <code>QTreeView</code> with items from my own model (<code>QAbstractItemModel</code> derived). Now I would like to style the items (with a stylesheet on the <code>QTreeView</code>) so that depending on various properties they would have various backgrounds.</p> <p>Also it seems that this problem applies to any Model/View containers. Not just <code>QTreeView</code>.</p> <hr> <p>For example doing alternate backgrounds is easy. <code>alternatingRowColors</code> on the <code>QTreeView</code> has to be <code>true</code>. Then in stylesheet you may use <code>:alternate</code> pseudo-selector to change properties for the alternate items so:</p> <pre><code>QTreeView::item { background: green; } QTreeView::item:alternate { background: blue; } </code></pre> <hr> <p>Doing selected items is similarly simple. In fact doing anything that is handled by Qt's pseudo-selectors is easy.</p> <p>But what about properties that are not pseudo-selectors? In particular how to select style based on values associated with <code>ItemDataRole</code> (which seams to be the only reasonably generic method of storing data in models)?</p> <p><em>Note that there is a trick. If for example you do not use checked state you might "reuse" that state to map to something of your own and then you have a pseudo-selector for it... But this is just a workaround and not even a general one.</em></p> <hr> <p>With <code>QTreeWidget</code> it seems you can go by having a dedicated <code>QWidget</code>-derived class for the items where you would add <code>Q_PROPERTY</code> with whatever you want. Then you can access that property by name in the stylesheet.</p> <p>See for example <a href="http://www.qtcentre.org/threads/30095-Using-custom-Q_PROPERTY-with-Stylesheet" rel="nofollow">"Using custom Q_PROPERTY with Stylesheet" question on Qt Centre</a> and <a href="http://qt-project.org/doc/qt-4.7/stylesheet-examples.html" rel="nofollow">"Trigger an update for the widget while using dynamic properties." note at the end of Qt Style Sheets Examples</a>.</p> <p>But the <code>*View</code> classes do not have any <code>QWidget</code>s or even <code>QObject</code>s for their items (or at least not public accessible ones).</p> <hr> <p>There is also possibility to provide own <code>QAbstractItemDelegate</code>, possibly one derived from <code>QStyledItemDelegate</code>. But that makes stylesheet interaction a bit harder.</p> <p>With simple staff like <code>background-color</code> property it seems doable. But how would you simulate <code>border-image</code>, <code>padding</code> and many other styles in complex sets?</p> <p>Not to mention that once you write an item delegate the code is frozen. If <code>Qt</code> changes ways of rendering stylesheet (improves it somehow) you will not benefit from it... Also is makes logic/presentation separation a bit harder. Now you need a programmer to style those items, not just a CSS-enabled graphics-guy...</p> <hr> <p>So is there any way to subclass in stylesheet based on model-provided properties/data?</p>
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    1. PTQuestion
    1. USAdam Badura
    1. USAdam Badura
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    1. COI found a similar question on a different forum (http://lists.qt.nokia.com/public/qt-interest/2010-May/023771.html). But it is a bit old now and with little activity so I thought about asking it here again. Hoping for more constructive or knowledgeable answers.
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      1. POStyling Qt Model/View items based on their ItemDataRole properties
      1. USAdam Badura
    2. COAnother question trying to achieve similar effect: http://stackoverflow.com/questions/1982351/using-multiple-qstyleditemdelegate-with-stylesheets with a negative answer.
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      1. POStyling Qt Model/View items based on their ItemDataRole properties
      1. USAdam Badura
    3. CODue to lack of activity here I asked the question on Qt Centre (see http://www.qtcentre.org/threads/53210-Styling-Model-View-items-based-on-their-ItemDataRole-properties) and got a negative reply (cannot be done) from "wysota".
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      1. POStyling Qt Model/View items based on their ItemDataRole properties
      1. USAdam Badura
 

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