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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 QLegendMarker clicked signal to show/hide corresponding series
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in chart. The connect marker button connects clicked signal from all markers in legend to handleMarkerClicked slot.
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\image examples_legendmarkers.png
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Our application has buttons for adding or removing series in chart and button to connect or disconnect legend markers clicked signal to our handler. In the image above,
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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 legend to our handler. To avoid conncecting 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 event to QLegendMarker.
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\snippet ../examples/legendmarkers/mainwidget.cpp 4
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Then we check the type of marker. This is needed if we want to access the detailed methods of the marker and cast it to correct type.
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If all we need is the pointer to QAbstractSeries, the casting isn't necessary. In case of pie or bar series, we may need the pointer to 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 marker is clicked. To do so, we get the pointer to related series from marker and toggle its visibility.
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Because the legend marker follows the visibility of the series by default, we also set the marked back to visible. If we don't do that, the marker will be
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invisible in 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 marker invisible when 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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