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/*!
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\example examples/donut
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\title Donut example
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\subtitle
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This example shows how to use create a nested donuts chart using QPieSeries API.
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Let's start by creating a QChartView instance and enabling the Antialiasing on it. Last line enables the animations of the chart.
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\snippet ../examples/donut/widget.cpp 1
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Three variables are defined that will be used to define the donut chart. Min and max size define the relative size of the whole donut.
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minSize is the relative inner size of the smallest donut. maxSize is the relative outer size of the biggest donut.
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\snippet ../examples/donut/widget.cpp 2
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Following block of code defines the individual donuts and their slices. First new QPieSeries object is created.
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Callign setDonut() changes pie into a donut. The number of slices in each donut is randomized.
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The internal for loop creates the slices with a random value and label same as the value.
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Next the label of the slice is set to be visible and its color is set to white.
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To make the example more interesting the hovered signal of the slice is connected to widget's slot which inner workings are explained later.
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Finally the slice is added to the donut. The donut's size is adjusted to achive the nesting of the donuts.
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Then the donut is added to the widget's list of donuts and to the chart.
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\snippet ../examples/donut/widget.cpp 3
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Finally the widget is placed in a layout used by the application.
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\snippet ../examples/donut/widget.cpp 4
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To make the example more interesting the donuts are rotated randomly every 1.25 sec.
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\snippet ../examples/donut/widget.cpp 5
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The widget's updatedRotation slot is defined below.
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It goes through all of the donuts and modifies thier current rotation by a random value.
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\snippet ../examples/donut/widget.cpp 6
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The earlier mentioned explodeSlice slot code is provided below.
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If the slice is set to exploded then stop the timer that controls the donuts rotation.
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Then the slice's start and end agles are obtained from the slice.
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To highlight the selected slice all the other donuts that lie outward from the one that contains the selected slice
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have their start and end angles modified so that they wouldn't "block" the way for the hightlighted slice.
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If the slice is no longer selected return to the original state.
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\snippet ../examples/donut/widget.cpp 7
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*/
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