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/*!
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\example examples/legendmarkers
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\title LegendMarkers Example
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\subtitle
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The example shows how to make use of legend markers. In this example we create an application which uses the QLegendMarker clicked signal to show/hide the corresponding series
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in a chart. The connect marker button connects a clicked signal from all markers in a legend to the handleMarkerClicked slot.
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\image examples_legendmarkers.png
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Our application has buttons for adding or removing a series in a chart and a button to connect or disconnect the legend markers clicked signal to our handler.
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In the image above we have connected the markers and clicked on one of them.
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\snippet ../examples/legendmarkers/mainwidget.cpp 1
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Here we connect the markers in the legend to our handler. To avoid connecting the same marker more than once, we first disconnect it.
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\snippet ../examples/legendmarkers/mainwidget.cpp 2
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Here we disconnect all markers from our handler.
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\snippet ../examples/legendmarkers/mainwidget.cpp 3
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In our handler we first cast the sender of the event to the QLegendMarker.
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\snippet ../examples/legendmarkers/mainwidget.cpp 4
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Then we check the type of the marker. This is required if we want to access the detailed methods of the marker and cast it to the correct type.
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If all we need is the pointer to QAbstractSeries, the casting isn't necessary. In case of a pie or bar series, we may need the pointer to a related QPieSlice or QBarSet.
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\snippet ../examples/legendmarkers/mainwidget.cpp 5
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We want to toggle the visibility of the series, when the marker is clicked. To do so, we get the pointer to a related series from the marker and toggle its visibility.
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Since the legend marker follows the visibility of the series by default, we also set the marked back to visible. If we don't do so, the marker will be
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invisible in the legend and we can't click on it anymore.
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\snippet ../examples/legendmarkers/mainwidget.cpp 6
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Instead of making the marker invisible when the series is hidden, we dim the color of the marker. Here we do it by modifying the color of the laberBrush.
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*/
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