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<td >Qt 5.12</td><td ><a href="qtquick-index.html">Qt Quick</a></td><td >Qt Quick TableViews examples - Pixelator</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right"><a href="qtquick-index.html">Qt 5.12.6 Reference Documentation</a></td>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#running-the-example">Running the Example</a></li>
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<h1 class="title">Qt Quick TableViews examples - Pixelator</h1>
<span class="subtitle"></span>
<!-- $$$tableview/pixelator-brief -->
<p>The Pixelator example shows how a QML <a href="qml-qtquick-tableview.html">TableView</a> and a delegate can be used for custom table models.</p>
<!-- @@@tableview/pixelator -->
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<div class="descr"> <a name="details"></a>
<p class="centerAlign"><img src="images/qt-pixelator.png" alt="" /></p><a name="running-the-example"></a>
<h2 id="running-the-example">Running the Example</h2>
<p>To run the example from Qt Creator, open the <b>Welcome</b> mode and select the example from <b>Examples</b>. For more information, visit Building and Running an Example.</p>
<pre class="cpp">
<span class="keyword">class</span> ImageModel : <span class="keyword">public</span> <span class="type">QAbstractTableModel</span>
{
Q_OBJECT
Q_PROPERTY(<span class="type">QString</span> source READ source WRITE setSource NOTIFY sourceChanged)
<span class="keyword">public</span>:
ImageModel(<span class="type">QObject</span> <span class="operator">*</span>parent <span class="operator">=</span> nullptr);
<span class="type">QString</span> source() <span class="keyword">const</span>;
<span class="type">void</span> setSource(<span class="keyword">const</span> <span class="type">QString</span> <span class="operator">&</span>source);
<span class="type">int</span> rowCount(<span class="keyword">const</span> <span class="type">QModelIndex</span> <span class="operator">&</span>parent <span class="operator">=</span> <span class="type">QModelIndex</span>()) <span class="keyword">const</span> override;
<span class="type">int</span> columnCount(<span class="keyword">const</span> <span class="type">QModelIndex</span> <span class="operator">&</span>parent <span class="operator">=</span> <span class="type">QModelIndex</span>()) <span class="keyword">const</span> override;
<span class="type">QVariant</span> data(<span class="keyword">const</span> <span class="type">QModelIndex</span> <span class="operator">&</span>index<span class="operator">,</span> <span class="type">int</span> role <span class="operator">=</span> <span class="type">Qt</span><span class="operator">::</span>DisplayRole) <span class="keyword">const</span> override;
<span class="type">QVariant</span> headerData(<span class="type">int</span> <span class="comment">/* section */</span><span class="operator">,</span> <span class="type">Qt</span><span class="operator">::</span>Orientation <span class="comment">/* orientation */</span><span class="operator">,</span>
<span class="type">int</span> role) <span class="keyword">const</span> override;
<span class="keyword">signals</span>:
<span class="type">void</span> sourceChanged();
<span class="keyword">private</span>:
<span class="type">QString</span> m_source;
<span class="type">QImage</span> m_image;
};
</pre>
<p>We only require a simple, read-only table model. Thus, we need to implement functions to indicate the dimensions of the image and supply data to the <a href="qml-qtquick-tableview.html">TableView</a>. We use the Qt Property System and a source property as <code>QString</code> to set the path of the image.</p>
<pre class="cpp">
<span class="type">void</span> ImageModel<span class="operator">::</span>setSource(<span class="keyword">const</span> <span class="type">QString</span> <span class="operator">&</span>source)
{
<span class="keyword">if</span> (m_source <span class="operator">=</span><span class="operator">=</span> source)
<span class="keyword">return</span>;
beginResetModel();
m_source <span class="operator">=</span> source;
m_image<span class="operator">.</span>load(m_source);
endResetModel();
}
</pre>
<p>Here we load the image when the source path is set. When the source path has changed, we need to call <code>beginResetModel()</code> before. After the image has been loaded, we need to call <code>endResetModel()</code>.</p>
<pre class="cpp">
<span class="type">int</span> ImageModel<span class="operator">::</span>rowCount(<span class="keyword">const</span> <span class="type">QModelIndex</span> <span class="operator">&</span>parent) <span class="keyword">const</span>
{
<span class="keyword">if</span> (parent<span class="operator">.</span>isValid())
<span class="keyword">return</span> <span class="number">0</span>;
<span class="keyword">return</span> m_image<span class="operator">.</span>height();
}
<span class="type">int</span> ImageModel<span class="operator">::</span>columnCount(<span class="keyword">const</span> <span class="type">QModelIndex</span> <span class="operator">&</span>parent) <span class="keyword">const</span>
{
<span class="keyword">if</span> (parent<span class="operator">.</span>isValid())
<span class="keyword">return</span> <span class="number">0</span>;
<span class="keyword">return</span> m_image<span class="operator">.</span>width();
}
</pre>
<p>The row and column count is set to image height and width, respectively.</p>
<pre class="cpp">
<span class="type">QVariant</span> ImageModel<span class="operator">::</span>data(<span class="keyword">const</span> <span class="type">QModelIndex</span> <span class="operator">&</span>index<span class="operator">,</span> <span class="type">int</span> role) <span class="keyword">const</span>
{
<span class="keyword">if</span> (<span class="operator">!</span>index<span class="operator">.</span>isValid() <span class="operator">|</span><span class="operator">|</span> role <span class="operator">!</span><span class="operator">=</span> <span class="type">Qt</span><span class="operator">::</span>DisplayRole)
<span class="keyword">return</span> <span class="type">QVariant</span>();
<span class="keyword">return</span> qGray(m_image<span class="operator">.</span>pixel(index<span class="operator">.</span>column()<span class="operator">,</span> index<span class="operator">.</span>row()));
}
</pre>
<p>This overloaded function allows us to access the pixel data from the image. When we call this function with the display role, we return the pixel's gray value.</p>
<pre class="cpp">
qmlRegisterType<span class="operator"><</span>ImageModel<span class="operator">></span>(<span class="string">"ImageModel"</span><span class="operator">,</span> <span class="number">1</span><span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> <span class="string">"ImageModel"</span>);
</pre>
<p>We need to register our model in the QML type system to be able to use it from the QML side.</p>
<pre class="qml">
Component {
id: pixelDelegate
Item {
readonly property real gray: model.display / 255.0
readonly property real size: 16
implicitWidth: size
implicitHeight: size
</pre>
<p>Each pixel in the <code>TableView</code> is displayed via a delegate component. It contains an item that has an implicit height and width defining the cell size of the table. It also has a property for the gray value of the pixel that is retrieved from the model.</p>
<pre class="qml">
Rectangle {
id: rect
anchors.centerIn: parent
color: "#09102b"
radius: size - gray * size
implicitWidth: radius
implicitHeight: radius
</pre>
<p>Inside the <code>Item</code>, there is a rounded <code>Rectangle</code> with the size and radius according to the pixel's gray value.</p>
<pre class="qml">
MouseArea {
anchors.fill: parent
hoverEnabled: true
onEntered: rect.color = "#cecfd5"
onExited: colorAnimation.start()
}
</pre>
<p>For a little bit of interaction, we place a <code>MouseArea</code> inside the <code>Item</code> and change the Rectangle's color on mouse over.</p>
<pre class="qml">
ColorAnimation on color {
id: colorAnimation
running: false
to: "#41cd52"
duration: 1500
}
</pre>
<p>The <code>Rectangle</code> also has a short color animation to fade between the colors when it is changed.</p>
<pre class="qml">
TableView {
id: tableView
anchors.fill: parent
model: ImageModel {
source: ":/qt.png"
}
delegate: pixelDelegate
}
</pre>
<p>The <code>TableView</code> spans over the whole window and has an instance of our custom <code>ImageModel</code> attached.</p>
<p>Files:</p>
<ul>
<li><a href="qtquick-tableview-pixelator-imagemodel-cpp.html">tableview/pixelator/imagemodel.cpp</a></li>
<li><a href="qtquick-tableview-pixelator-imagemodel-h.html">tableview/pixelator/imagemodel.h</a></li>
<li><a href="qtquick-tableview-pixelator-main-cpp.html">tableview/pixelator/main.cpp</a></li>
<li><a href="qtquick-tableview-pixelator-main-qml.html">tableview/pixelator/main.qml</a></li>
<li><a href="qtquick-tableview-pixelator-pixelator-pro.html">tableview/pixelator/pixelator.pro</a></li>
</ul>
<p>Images:</p>
<ul>
<li><a href="images/used-in-examples/tableview/pixelator/qt.png">tableview/pixelator/qt.png</a></li>
</ul>
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Mageia
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7
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i586
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media
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core-updates
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6e2327ca1c896c6d674ae53117299f21
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files
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1729
