在Windows 10的UWP（通用Windows應用）中創建自定義形狀控件

Question

我想創建一個自定義的Shape控件，該控件根據某些自定義屬性繪制不同的形狀，例如Polygon ， Ellipse ， Rectangle等。

我能夠像這樣創建一個自定義模板控件ColorShape ：

<Style TargetType="local:CustomShape">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="local:CustomShape">
                <ContentControl x:Name="shapeParent">
                </ContentControl>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

然后，重寫OnTemplateChanged方法，並在shapeParent ContentControl插入相應的Shape控件。

但是我想要的是實際擴展Shape ，以便我可以用相同的方式處理所有形狀，包括framewok和custom。

在WPF中，我們能夠擴展Shape並覆蓋屬性DefiningGeometry 。 在UWP中，不存在任何要覆蓋的DefiningGeometry屬性。

如何創建自定義Shape控件並定義相應的Geometry？

Answer 1

我發現在UWP中創建自定義形狀的唯一方法是擴展Path類並設置其Data屬性。

在布局相關部分（例如LayoutUpdated事件或ArrangeOverride方法）時，請勿完成更新Data屬性以解決其他依賴項屬性（例如Width ）變化的問題。

設置Data會導致另一個布局運行，因此將其設置為在此期間調用的任何內容都會導致異常：

檢測到布局周期。 布局無法完成

我使用的方法是為屬性更改的事件注冊處理程序，並在其中更新Data 。

我寫了一篇博客文章 ，對它進行了更詳細的解釋。

這是我使用的示例：

public class CandlestickShape : Path
{
    public double StartValue
    {
        get { return Convert.ToDouble(GetValue(StartValueProperty)); }
        set { SetValue(StartValueProperty, value); }
    }
    public static readonly DependencyProperty StartValueProperty =
        DependencyProperty.Register("StartValue", typeof(double), typeof(CandlestickShape), new PropertyMetadata(0));

    public double EndValue
    {
        get { return Convert.ToDouble(GetValue(EndValueProperty)); }
        set { SetValue(EndValueProperty, value); }
    }
    public static readonly DependencyProperty EndValueProperty =
        DependencyProperty.Register("EndValue", typeof(double), typeof(CandlestickShape), new PropertyMetadata(0));

    public double MinValue
    {
        get { return Convert.ToDouble(GetValue(MinValueProperty)); }
        set { SetValue(MinValueProperty, value); }
    }
    public static readonly DependencyProperty MinValueProperty =
        DependencyProperty.Register("MinValue", typeof(double), typeof(CandlestickShape), new PropertyMetadata(0));

    public double MaxValue
    {
        get { return Convert.ToDouble(GetValue(MaxValueProperty)); }
        set { SetValue(MaxValueProperty, value); }
    }
    public static readonly DependencyProperty MaxValueProperty =
        DependencyProperty.Register("MaxValue", typeof(double), typeof(CandlestickShape), new PropertyMetadata(0));

    /// <summary>
    /// Defines how many Pixel should be drawn for one Point
    /// </summary>
    public double PixelPerPoint
    {
        get { return Convert.ToDouble(GetValue(PointsPerPixelProperty)); }
        set { SetValue(PointsPerPixelProperty, value); }
    }
    public static readonly DependencyProperty PointsPerPixelProperty =
        DependencyProperty.Register("PixelPerPoint", typeof(double), typeof(CandlestickShape), new PropertyMetadata(0));

    public CandlestickShape()
    {
        this.RegisterPropertyChangedCallback(CandlestickShape.WidthProperty, new DependencyPropertyChangedCallback(RenderAffectingPropertyChanged));
        this.RegisterPropertyChangedCallback(CandlestickShape.StartValueProperty, new DependencyPropertyChangedCallback(RenderAffectingPropertyChanged));
        this.RegisterPropertyChangedCallback(CandlestickShape.EndValueProperty, new DependencyPropertyChangedCallback(RenderAffectingPropertyChanged));
        this.RegisterPropertyChangedCallback(CandlestickShape.MinValueProperty, new DependencyPropertyChangedCallback(RenderAffectingPropertyChanged));
        this.RegisterPropertyChangedCallback(CandlestickShape.MaxValueProperty, new DependencyPropertyChangedCallback(RenderAffectingPropertyChanged));
        this.RegisterPropertyChangedCallback(CandlestickShape.PointsPerPixelProperty, new DependencyPropertyChangedCallback(RenderAffectingPropertyChanged));
    }

    private void RenderAffectingPropertyChanged(DependencyObject o, DependencyProperty e)
    {
        (o as CandlestickShape)?.SetRenderData();
    }

    private void SetRenderData()
    {
        var maxBorderValue = Math.Max(this.StartValue, this.EndValue);
        var minBorderValue = Math.Min(this.StartValue, this.EndValue);
        double topLineLength = (this.MaxValue - maxBorderValue) * this.PixelPerPoint;
        double bottomLineLength = (minBorderValue - this.MinValue) * this.PixelPerPoint;
        double bodyLength = (this.EndValue - this.StartValue) * this.PixelPerPoint;

        var fillColor = new SolidColorBrush(Colors.Green);
        if (bodyLength < 0)
            fillColor = new SolidColorBrush(Colors.Red);

        bodyLength = Math.Abs(bodyLength);

        var bodyGeometry = new RectangleGeometry
        {
            Rect = new Rect(new Point(0, topLineLength), new Point(this.Width, topLineLength + bodyLength)),
        };

        var topLineGeometry = new LineGeometry
        {
            StartPoint = new Point(this.Width / 2, 0),
            EndPoint = new Point(this.Width / 2, topLineLength)
        };

        var bottomLineGeometry = new LineGeometry
        {
            StartPoint = new Point(this.Width / 2, topLineLength + bodyLength),
            EndPoint = new Point(this.Width / 2, topLineLength + bodyLength + bottomLineLength)
        };

        this.Data = new GeometryGroup
        {
            Children = new GeometryCollection
            {
                bodyGeometry,
                topLineGeometry,
                bottomLineGeometry
            }
        };
        this.Fill = fillColor;
        this.Stroke = new SolidColorBrush(Colors.Black);
    }

    protected override Size ArrangeOverride(Size finalSize)
    {
        double height = (MaxValue - MinValue) * PixelPerPoint;
        return new Size(this.Width, height);
    }

    protected override Size MeasureOverride(Size availableSize)
    {
        double height = (MaxValue - MinValue) * PixelPerPoint;
        return new Size(this.Width, height);
    }
}