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/*!
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\example examples/barmodelmapper
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\title BarModelMapper example
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\subtitle
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This example shows how to use QAbstractItemModel derived model as the data for the bar series.
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\image examples_barmodelmapper.png
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Let's start by creating an instance of CustomTableModel class.
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CustomTableModel class is derived from QAbstractTableModel and it was created for the purpose of this example.
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The constructor of this class populates the internal data store of the model with the data that is good for our chart example.
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\snippet ../examples/barmodelmapper/tablewidget.cpp 1
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We now have a model with data that we would like to display both on the chart and in a QTableView.
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First, we create QTableView and tell it use the model as a data source. To have the data presented nicely the minimum width of the table view is set and its headers resize mode changed to stretch.
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\snippet ../examples/barmodelmapper/tablewidget.cpp 2
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Now we need QChart instance to display the same data on the chart.
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We also enable animations. It makes it easier to see how modifying the model's data affect the chart.
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\snippet ../examples/barmodelmapper/tablewidget.cpp 3
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First line of the code below creates new grouped bar series. Variables firstRow and rowCount are used to define a custom model mapping.
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Custom mapping allows to take only part of the data from the model. In this case data from 5 rows starting with the row with the index 3.
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Following three lines create an instance of QVBarModelMapper class and specifie that data for the bar sets should be taken from the model's columns with indexes from 1 to 4(inclusive).
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To create a connection between the series and the model we set both of those objects to QVBarModelMapper.
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Finally the series is added to the chart.
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\snippet ../examples/barmodelmapper/tablewidget.cpp 4
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To show in QTableView which data coresponds with which bar set this example uses table coloring.
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When series is added to the chart it is assigned a color beased on the currently selected theme.
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Code below extracts that color from the series and uses it to create colored QTableView.
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Coloring of the view is not a part of the QChart functionality.
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\snippet ../examples/barmodelmapper/tablewidget.cpp 5
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We would like to have categories placed on the chart's axis that describe what the data means.
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Next snippet shows how to do that.
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\snippet ../examples/barmodelmapper/tablewidget.cpp 6
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To avoid setting up the QGraphicsScene we use QChartView class that does it for us. QChart object pointer is used as a parameter of the QChartView constructor.
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To make the render look nicer Antialiasing is turned on and the minimum size of the chartView widget is set.
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\snippet ../examples/barmodelmapper/tablewidget.cpp 7
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Finally we place both widgets in a layout and use the layout as the application layout.
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\snippet ../examples/barmodelmapper/tablewidget.cpp 8
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Application is ready. Try modifying the data in the table view and see how it affects the chart.
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*/
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