可点击的图例在核心情节

Question

我使用Core Plot文件创建我的图表。但是CorePlot不包含"click on legend item"事件。

如何检测用户在图例项上的点击?

class ViewController: NSViewController, CPTPlotDataSource, CPTPieChartDataSource {
@IBOutlet weak var graphView: CPTGraphHostingView!
override func viewDidLoad() {
    super.viewDidLoad()
    let graph = CPTXYGraph(frame: CGRect.zero)        
    var axes = graph.axisSet as! CPTXYAxisSet
    var lineStyle = CPTMutableLineStyle()
    lineStyle.lineWidth = 0
    axes.xAxis?.axisLineStyle = lineStyle
    axes.yAxis?.axisLineStyle = lineStyle

    var pie = CPTPieChart()
    pie.pieRadius = 100
    pie.dataSource = self
    pie.centerAnchor = CGPoint(x: 0.18, y: 0.75)
    graph.add(pie)        
    var theLegend=CPTLegend(graph: graph)
    var legendFill=CPTFill(color: CPTColor.gray())
    theLegend.fill = legendFill
    var legendLineStyle = CPTMutableLineStyle()
    legendLineStyle.lineColor = CPTColor.white()
    theLegend.borderLineStyle = legendLineStyle
    theLegend.cornerRadius = 2.0
    theLegend.frame = CGRect(x: 0, y: 0, width: 0.1, height: 50)
    theLegend.numberOfColumns = 1
    graph.legend = theLegend
    graph.legendDisplacement = CGPoint(x: 0.5, y: 300)
    self.graphView.hostedGraph = graph
}

Answer 1

Core Plot图例可以有一个委托，在鼠标向下、鼠标向上和/或被选中(鼠标向下和鼠标向上在同一项上)事件时调用。有关可用方法的详细信息，请参阅CPTLegendDelegate协议。除非你需要一些委托没有涵盖的特定行为，否则你不需要担心响应器链。

Answer 2

如果您深入研究Core Plot的源代码，您可以遵循CPTLegend的继承链一直到CPTLayer:

https://github.com/core-plot/core-plot/blob/master/framework/Source/CPTLegend.hhttps://github.com/core-plot/core-plot/blob/master/framework/Source/CPTBorderedLayer.hhttps://github.com/core-plot/core-plot/blob/master/framework/Source/CPTAnnotationHostLayer.hhttps://github.com/core-plot/core-plot/blob/master/framework/Source/CPTLayer.h

如果你检查CPTLayer的头文件，它符合CPTResponder，如果你去CPTResponder的源代码:

https://github.com/core-plot/core-plot/blob/master/framework/Source/CPTResponder.h

你会注意到有两个相关的方法:

-(BOOL)pointingDeviceDownEvent:(非空CPTNativeEvent *)事件atPoint:(CGPoint)interactionPoint;

-(BOOL)pointingDeviceUpEvent:(非空CPTNativeEvent *)事件atPoint:(CGPoint)interactionPoint;

我认为你可能做的是子类化CPTLegend和覆盖一个或两个方法取决于你需要检测点击