How to: Implement a Custom Pie Animation

• Nov 13, 2018
• 3 minutes to read

To implement a custom bar animation, design a class inheriting the PieAnimationBase class and override the PieAnimationBase.ApplyState method which determines the transformations applied to an individual pie segment.

GripPieAnimation.cs

using DevExpress.XtraCharts;
using System.Drawing;

namespace AnimationExample {
    class GripPieAnimation : PieAnimationBase {
        public static PointF CalculateOffset(RectangleF pointBounds, float progress) {
            float offsetX = (pointBounds.Width / 2 + pointBounds.X) * progress;
            float offsetY = (pointBounds.Height / 2 + pointBounds.Y) * progress;
            return new PointF(offsetX, offsetY);
        }
        public override void ApplyState(
                SceneModifier modifier, 
                RectangleF diagramBounds, 
                PieSeriesPointLayoutParameters pieParameters, 
                float progress
        ) {
            float pieCenterX = pieParameters.PieCenter.X;
            float pieCenterY = pieParameters.PieCenter.Y;
            float scale = (progress <= 0.5)
                ? 1 - 0.2f * progress
                : 0.8f + 0.2f * progress;

            // Note that methods requiered for correct transform are called in inverse order.
            // This is a feature of affine transformations.
            modifier.Translate(pieCenterX, pieCenterY);
            modifier.Scale(scale, scale);
            modifier.Translate(-pieCenterX, -pieCenterY);
        }

        protected override ChartElement CreateObjectForClone() {
            return new GripPieAnimation();
        }
    }
}

MainForm.cs

protected override void OnLoad(EventArgs e) {
    base.OnLoad(e);

    view.Animation = new GripPieAnimation {
        BeginTime = new TimeSpan(0, 0, 0, 0),
        PointDelay = new TimeSpan(0, 0, 0, 0, 250),
        Duration = new TimeSpan(0, 0, 0, 1, 500),
        EasingFunction = new LinearEasingFunction {
            EasingMode = EasingMode.Out
        }
    };

    chartControl.AnimationStartMode = ChartAnimationMode.OnLoad;
}

private void buttonOnClick(object sender, EventArgs e) {
    chartControl.Animate();
}

GripPieAnimation.vb

Imports DevExpress.XtraCharts
Imports System.Drawing

Namespace AnimationExample
    Friend Class GripPieAnimation
        Inherits PieAnimationBase

        Public Shared Function CalculateOffset(ByVal pointBounds As RectangleF, ByVal progress As Single) As PointF
            Dim offsetX As Single = (pointBounds.Width / 2 + pointBounds.X) * progress
            Dim offsetY As Single = (pointBounds.Height / 2 + pointBounds.Y) * progress
            Return New PointF(offsetX, offsetY)
        End Function
        Public Overrides Sub ApplyState(ByVal modifier As SceneModifier, ByVal diagramBounds As RectangleF, ByVal pieParameters As PieSeriesPointLayoutParameters, ByVal progress As Single)
            Dim pieCenterX As Single = pieParameters.PieCenter.X
            Dim pieCenterY As Single = pieParameters.PieCenter.Y
            Dim scale As Single = If(progress <= 0.5, 1 - 0.2F * progress, 0.8F + 0.2F * progress)

            ' Note that methods requiered for correct transform are called in inverse order.
            ' This is a feature of affine transformations.
            modifier.Translate(pieCenterX, pieCenterY)
            modifier.Scale(scale, scale)
            modifier.Translate(-pieCenterX, -pieCenterY)
        End Sub

        Protected Overrides Function CreateObjectForClone() As ChartElement
            Return New GripPieAnimation()
        End Function
    End Class
End Namespace

MainForm.vb

Protected Overrides Sub OnLoad(ByVal e As EventArgs)
    MyBase.OnLoad(e)

    view.Animation = New GripPieAnimation With { _
        .BeginTime = New TimeSpan(0, 0, 0, 0), .PointDelay = New TimeSpan(0, 0, 0, 0, 250), .Duration = New TimeSpan(0, 0, 0, 1, 500), .EasingFunction = New LinearEasingFunction With {.EasingMode = EasingMode.Out} _
    }

    chartControl.AnimationStartMode = ChartAnimationMode.OnLoad
End Sub

Private Sub buttonOnClick(ByVal sender As Object, ByVal e As EventArgs) Handles btnAnimate.Click
    chartControl.Animate()
End Sub