指标图形渲染器

有些指标需要特殊的绘图样式，例如 BollingerBands 指标需要两条线，或者 Fractals 指标需要点。在这些情况下，您需要在 ChartIndicatorElement 中明确指定指标的图形渲染器。

var chartIndicatorElement = new ChartIndicatorElement()
{
	IndicatorPainter = new BollingerBandsPainter(),
};

让我们以 Fractals 指标为例，考虑如何创建自定义 IndicatorPainter。

所有 IndicatorPainters 必须继承自基类 BaseChartIndicatorPainter<TIndicator>，或实现接口 IChartIndicatorPainter：

/// <summary>
/// 用于 <see cref="Fractals"/> 的图表元素。
/// </summary>
[Indicator(typeof(Fractals))]
public class FractalsPainter : BaseChartIndicatorPainter<Fractals>
{
	...
}

让我们定义将表示上部和下部分形的图表元素 ChartLineElement:

/// <summary>
/// 用于 <see cref="Fractals"/> 的图表元素。
/// </summary>
[Indicator(typeof(Fractals))]
public class FractalsPainter : BaseChartIndicatorPainter<Fractals>
{
	/// <summary>
	/// <see cref="Fractals.Up"/> dots color.
	/// </summary>
	[Display(
		ResourceType = typeof(LocalizedStrings),
		Name = LocalizedStrings.Str2035Key,
		Description = LocalizedStrings.Str2036Key)]
	public ChartLineElement Up { get; }

	/// <summary>
	/// <see cref="Fractals.Down"/> dots color.
	/// </summary>
	[Display(
		ResourceType = typeof(LocalizedStrings),
		Name = LocalizedStrings.Str2037Key,
		Description = LocalizedStrings.Str2038Key)]
	public ChartLineElement Down { get; }
	...
}

在 FractalsPainter 的构造函数中，我们设置它们的值和主要属性，例如颜色、粗细和绘图样式。之后，我们将它们作为图表的子元素添加进去：

...

/// <summary>
/// 创建实例。
/// </summary>
public FractalsPainter()
{
	Up = new ChartLineElement { Color = Colors.Green };
	Down = new ChartLineElement { Color = Colors.Red };
	Up.Style = Down.Style = DrawStyles.Dot;
	Up.StrokeThickness = Down.StrokeThickness = 4;
	AddChildElement(Up);
	AddChildElement(Down);
}

...

重写 OnDraw 方法，在该方法中，我们使用 DrawValues 方法绘制指示器：

...
/// <inheritdoc />
protected override bool OnDraw(Fractals ind, IDictionary<IIndicator, IList<ChartDrawData.IndicatorData>> data)
{
	var result = false;
	result |= DrawValues(data[ind.Down], Down);
	result |= DrawValues(data[ind.Up], Up);
	return result;
}
...

FractalsPainter 的完整代码：

/// <summary>
/// 用于 <see cref="Fractals"/> 的图表元素。
/// </summary>
[Indicator(typeof(Fractals))]
public class FractalsPainter : BaseChartIndicatorPainter<Fractals>
{
	/// <summary>
	/// <see cref="Fractals.Up"/> dots color.
	/// </summary>
	[Display(
		ResourceType = typeof(LocalizedStrings),
		Name = LocalizedStrings.Str2035Key,
		Description = LocalizedStrings.Str2036Key)]
	public ChartLineElement Up { get; }
	/// <summary>
	/// <see cref="Fractals.Down"/> dots color.
	/// </summary>
	[Display(
		ResourceType = typeof(LocalizedStrings),
		Name = LocalizedStrings.Str2037Key,
		Description = LocalizedStrings.Str2038Key)]
	public ChartLineElement Down { get; }
	/// <summary>
	/// 创建实例。
	/// </summary>
	public FractalsPainter()
	{
		Up = new ChartLineElement { Color = Colors.Green };
		Down = new ChartLineElement { Color = Colors.Red };
		Up.Style = Down.Style = DrawStyles.Dot;
		Up.StrokeThickness = Down.StrokeThickness = 4;
		AddChildElement(Up);
		AddChildElement(Down);
	}
	/// <inheritdoc />
	protected override bool OnDraw(Fractals ind, IDictionary<IIndicator, IList<ChartDrawData.IndicatorData>> data)
	{
		var result = false;
		result |= DrawValues(data[ind.Down], Down);
		result |= DrawValues(data[ind.Up], Up);
		return result;
	}
	#region IPersistable
	/// <inheritdoc />
	public override void Load(SettingsStorage storage)
	{
		base.Load(storage);
		Up.Load(storage.GetValue<SettingsStorage>(nameof(Up)));
		Down.Load(storage.GetValue<SettingsStorage>(nameof(Down)));
	}
	/// <inheritdoc />
	public override void Save(SettingsStorage storage)
	{
		base.Save(storage);
		storage.SetValue(nameof(Up), Up.Save());
		storage.SetValue(nameof(Down), Down.Save());
	}
	#endregion
}