Plot labels

Classes/Plots/Plot.swift

@@ -27,6 +27,16 @@ open class Plot {
     /// If adaptAnimationType is set to .Custom, then this is the easing function you would like applied for the animation.
     open var customAnimationEasingFunction: ((_ t: Double) -> Double)?
 
+    // Labels
+    // #####################
+
+    /// The font to be used for the value label.
+    open var labelFont = UIFont.systemFont(ofSize: 8)
+    /// The colour of the value label font.
+    open var labelColor: UIColor = UIColor.black
+    /// How far to offset the vertical position of the label.
+    open var labelVerticalOffset: CGFloat = 0
+
     // Private Animation State
     // #######################
 

Classes/Protocols/ScrollableGraphViewDataSource.swift

@@ -5,4 +5,11 @@ public protocol ScrollableGraphViewDataSource : class {
     func value(forPlot plot: Plot, atIndex pointIndex: Int) -> Double
     func label(atIndex pointIndex: Int) -> String
     func numberOfPoints() -> Int // This now forces the same number of points in each plot.
+    func plotLabel(shouldShowPlotLabel plot: Plot, atIndex pointIndex: Int) -> Bool
+    func plotLabel(forPlot plot: Plot, atIndex pointIndex: Int) -> String?
+}
+
+extension ScrollableGraphViewDataSource {
+    func plotLabel(shouldShowPlotLabel plot: Plot, atIndex pointIndex: Int) -> Bool { return false }
+    func plotLabel(forPlot plot: Plot, atIndex pointIndex: Int) -> String? { return nil }
 }

Classes/ScrollableGraphView.swift

@@ -94,6 +94,7 @@ import UIKit
     // Labels
     private var labelsView = UIView()
     private var labelPool = LabelPool()
+    private var plotLabelPool = [LabelPool]()
 
     // Data Source
     weak open var dataSource: ScrollableGraphViewDataSource? {
@@ -478,6 +479,7 @@ import UIKit
     private func addPlotToGraph(plot: Plot, activePointsInterval: CountableRange<Int>) {
         plot.graphViewDrawingDelegate = self
         self.plots.append(plot)
+        self.plotLabelPool.append(LabelPool())
         initPlot(plot: plot, activePointsInterval: activePointsInterval)
         startAnimations(withStaggerValue: 0.15)
     }
@@ -708,6 +710,7 @@ import UIKit
                 let deactivatedLabelPoints = filterPointsForLabels(fromPoints: deactivatedPoints)
                 let activatedLabelPoints = filterPointsForLabels(fromPoints: activatedPoints)
                 updateLabels(deactivatedPoints: deactivatedLabelPoints, activatedPoints: activatedLabelPoints)
+                updatePlotLabels(deactivatedPoints: deactivatedLabelPoints, activatedPoints: activatedLabelPoints)
             }
         }
     }
@@ -833,6 +836,42 @@ import UIKit
         }
     }
 
+    private func updatePlotLabels(deactivatedPoints: [Int], activatedPoints: [Int]) {
+        guard let dataSource = self.dataSource else {
+            return
+        }
+
+        for (index, plot) in plots.enumerated() {
+            let labelPool = plotLabelPool[index]
+
+            // Disable any labels for the deactivated points.
+            for point in deactivatedPoints {
+                labelPool.deactivateLabel(forPointIndex: point)
+            }
+
+            // Grab an unused label and update it to the right position for the newly activated poitns
+            for point in activatedPoints {
+                guard let plotLabelText = dataSource.plotLabel(forPlot: plot, atIndex: point) else {
+                    continue
+                }
+                let label = labelPool.activateLabel(forPointIndex: point)
+                label.text = plotLabelText
+                label.isHidden = !dataSource.plotLabel(shouldShowPlotLabel: plot, atIndex: point)
+                label.textColor = plot.labelColor
+                label.font = plot.labelFont
+
+                label.sizeToFit()
+
+                let position = calculatePosition(atIndex: point, value: dataSource.value(forPlot: plot, atIndex: point))
+                label.frame = CGRect(origin: CGPoint(x: position.x - label.frame.width / 2, y: position.y - label.frame.height + plot.labelVerticalOffset), size: label.frame.size)
+
+                _ = labelsView.subviews.filter { $0.frame.origin == label.frame.origin }.map { $0.removeFromSuperview() }
+
+                labelsView.addSubview(label)
+            }
+        }
+    }
+
     private func updateLabelsForCurrentInterval() {
         // Have to ensure that the labels are added if we are supposed to be showing them.
         if let ref = self.referenceLines {
@@ -845,6 +884,7 @@ import UIKit
 
                 let filteredPoints = filterPointsForLabels(fromPoints: activatedPoints)
                 updateLabels(deactivatedPoints: filteredPoints, activatedPoints: filteredPoints)
+                updatePlotLabels(deactivatedPoints: filteredPoints, activatedPoints: filteredPoints)
             }
         }
     }

graphview_example_code/GraphView/ViewController.swift

@@ -57,6 +57,28 @@ class ViewController: UIViewController, ScrollableGraphViewDataSource {
     // off many graphs with different plots, we are using one big switch
     // statement.
     func value(forPlot plot: Plot, atIndex pointIndex: Int) -> Double {
+        return dataValue(forPlot: plot, atIndex: pointIndex)
+    }
+
+    func label(atIndex pointIndex: Int) -> String {
+        // Ensure that you have a label to return for the index
+        return xAxisLabels[pointIndex]
+    }
+
+    // Uncomment the below to enable plot labels
+//    func plotLabel(forPlot plot: Plot, atIndex pointIndex: Int) -> String? {
+//        return "\(dataValue(forPlot: plot, atIndex: pointIndex))"
+//    }
+//
+//    func plotLabel(shouldShowPlotLabel plot: Plot, atIndex pointIndex: Int) -> Bool {
+//        return true
+//    }
+
+    func numberOfPoints() -> Int {
+        return numberOfDataItems
+    }
+
+    func dataValue(forPlot plot: Plot, atIndex pointIndex: Int) -> Double {
 
         switch(plot.identifier) {
 
@@ -89,15 +111,6 @@ class ViewController: UIViewController, ScrollableGraphViewDataSource {
         }
     }
 
-    func label(atIndex pointIndex: Int) -> String {
-        // Ensure that you have a label to return for the index
-        return xAxisLabels[pointIndex]
-    }
-
-    func numberOfPoints() -> Int {
-        return numberOfDataItems
-    }
-
     // Creating Different Kinds of Graphs
     // ##################################