How do I show data other than the chart points (x, y) in a Marker?

Question

I have figured out how to modify the text and x, y values that appear in a marker, but I can't figure out how to show other data in the marker.

Here's my marker currently:

Instead of the x and y values, I want to show two values that were used to calculate the y value:

"5 reps @ 200 lb"

Update: In other words, the point being shown on the chart is 233.3 (the y value). But I need to make the label display the 5 and the 200 that were used to calculate the result of 233.3 that is the point on the chart.

It looks like I would use func refreshContent(entry: ChartDataEntry, highlight: Highlight) but this takes a ChartDataEntry and the values I want to show are not data points (ChartDataEntry).

I've looked through all the Issues on the Github project and the closest thing I could find to a solution was this thread, but the answer doesn't really help a beginner level developer.

Can someone educate me about how to display non-data point data in a marker?

Update: Thanks to @RazibMollick for directing me to the solution which was to use the ChartDataEntry initializer that takes an additional argument ( ChartDataEntry(x:y:data:) ) in my generatedLineData method:

let numberFormatter = NumberFormatter()
let repetitions = numberFormatter.string(from: liftEvents[index].repetitions)
let weightLifted = numberFormatter.string(from: liftEvents[index].weightLifted)
let liftData = LiftData(repetitions: repetitions!, weightLifted: weightLifted!)

return ChartDataEntry(x: (thisDateInSeconds! - beginningDateInSeconds) / (3600.0 * 24.0), y: yValue, data: (liftData as AnyObject))

And in refreshContent(entry:highlight) I now have this:

open override func refreshContent(entry: ChartDataEntry, highlight: Highlight)
{
    let unit = UserDefaults.weightUnit()
    let liftData = entry.data as! LiftData
    setLabel(String(format: "%@ reps @ %@ \(unit)", liftData.repetitions, liftData.weightLifted))
}

Now I have this:

Now if I can just get those corners on the BalloonMarker to be rounded...

Razib Mollick · Accepted Answer · 2018-04-20T10:48:05.237

[Swift 4], I used their helper class from here.

I modified the classes like below (Setup your desire string in refreshContent that you wanted):

import Foundation
import Charts
open class BalloonMarker: MarkerImage
{
    open var color: UIColor?
    open var arrowSize = CGSize(width: 15, height: 11)
    open var font: UIFont?
    open var textColor: UIColor?
    open var insets = UIEdgeInsets()
    open var minimumSize = CGSize()

    fileprivate var labelns: NSString?
    fileprivate var _labelSize: CGSize = CGSize()
    fileprivate var _paragraphStyle: NSMutableParagraphStyle?
    fileprivate var _drawAttributes = [NSAttributedStringKey : Any]()

    public init(color: UIColor, font: UIFont, textColor: UIColor, insets: UIEdgeInsets)
    {
        super.init()

        self.color = color
        self.font = font
        self.textColor = textColor
        self.insets = insets

        _paragraphStyle = NSParagraphStyle.default.mutableCopy() as? NSMutableParagraphStyle
        _paragraphStyle?.alignment = .center
    }

    open override func offsetForDrawing(atPoint point: CGPoint) -> CGPoint
    {
        var offset = self.offset

        let chart = self.chartView

        var size = self.size

        if size.width == 0.0 && image != nil
        {
            size.width = image?.size.width ?? 0.0
        }
        if size.height == 0.0 && image != nil
        {
            size.height = image?.size.height ?? 0.0
        }

        let width = size.width
        let height = size.height
        let padding = CGFloat(8.0)
        var origin = point;
        origin.x -= width / 2;
        origin.y -= height;
        if origin.x + offset.x < 0.0
        {
            offset.x = -origin.x + padding
        }
        else if chart != nil && origin.x + width + offset.x > chart!.bounds.size.width
        {
            offset.x = chart!.bounds.size.width - origin.x - width - padding
        }

        if origin.y + offset.y < 0
        {
            offset.y = height + padding;
        }
        else if chart != nil && origin.y + height + offset.y > chart!.bounds.size.height
        {
            offset.y = chart!.bounds.size.height - origin.y - height - padding
        }

        return offset
    }

    open override func draw(context: CGContext, point: CGPoint)
    {
        if labelns == nil
        {
            return
        }
        let offset = self.offsetForDrawing(atPoint: point)
        let size = self.size

        var rect = CGRect(
            origin: CGPoint(
                x: point.x + offset.x,
                y: point.y + offset.y),
            size: size)
        rect.origin.x -= size.width / 2.0
        rect.origin.y -= size.height
        context.saveGState()

        if let color = color
        {
            context.setFillColor(color.cgColor)
            if(offset.y > 0) {
                context.beginPath()
                context.move(to: CGPoint(
                    x: rect.origin.x,
                    y: rect.origin.y + arrowSize.height))
                context.addLine(to: CGPoint(
                    x: rect.origin.x + (rect.size.width - arrowSize.width) / 2.0,
                    y: rect.origin.y + arrowSize.height))
                //arrow vertex
                context.addLine(to: CGPoint(
                    x: point.x,
                    y: point.y))
                context.addLine(to: CGPoint(
                    x: rect.origin.x + (rect.size.width + arrowSize.width) / 2.0,
                    y: rect.origin.y + arrowSize.height))
                context.addLine(to: CGPoint(
                    x: rect.origin.x + rect.size.width,
                    y: rect.origin.y + arrowSize.height))
                context.addLine(to: CGPoint(
                    x: rect.origin.x + rect.size.width,
                    y: rect.origin.y + rect.size.height))
                context.addLine(to: CGPoint(
                    x: rect.origin.x,
                    y: rect.origin.y + rect.size.height))
                context.addLine(to: CGPoint(
                    x: rect.origin.x,
                    y: rect.origin.y + arrowSize.height))
                context.fillPath()
            } else {
                context.beginPath()
                context.move(to: CGPoint(
                    x: rect.origin.x,
                    y: rect.origin.y))
                context.addLine(to: CGPoint(
                    x: rect.origin.x + rect.size.width,
                    y: rect.origin.y))
                context.addLine(to: CGPoint(
                    x: rect.origin.x + rect.size.width,
                    y: rect.origin.y + rect.size.height - arrowSize.height))
                context.addLine(to: CGPoint(
                    x: rect.origin.x + (rect.size.width + arrowSize.width) / 2.0,
                    y: rect.origin.y + rect.size.height - arrowSize.height))
                //arrow vertex
                context.addLine(to: CGPoint(
                    x: point.x,
                    y: point.y))
                context.addLine(to: CGPoint(
                    x: rect.origin.x + (rect.size.width - arrowSize.width) / 2.0,
                    y: rect.origin.y + rect.size.height - arrowSize.height))
                context.addLine(to: CGPoint(
                    x: rect.origin.x,
                    y: rect.origin.y + rect.size.height - arrowSize.height))
                context.addLine(to: CGPoint(
                    x: rect.origin.x,
                    y: rect.origin.y))
                context.fillPath()
            }
        }
        if (offset.y > 0) {
            rect.origin.y += self.insets.top + arrowSize.height
        } else {
            rect.origin.y += self.insets.top
        }
        rect.size.height -= self.insets.top + self.insets.bottom

        UIGraphicsPushContext(context)

        labelns?.draw(in: rect, withAttributes: _drawAttributes)

        UIGraphicsPopContext()

        context.restoreGState()
    }

    open override func refreshContent(entry: ChartDataEntry, highlight: Highlight)
    {
        //setLabel(String(entry.y))
        setLabel(String(format: "%.1f reps @ %.01f lb", entry.x, entry.y))
    }

    open func setLabel(_ label: String)
    {
        labelns = label as NSString

        _drawAttributes.removeAll()
        _drawAttributes[NSAttributedStringKey.font] = self.font
        _drawAttributes[NSAttributedStringKey.paragraphStyle] = _paragraphStyle
        _drawAttributes[NSAttributedStringKey.foregroundColor] = self.textColor

        _labelSize = labelns?.size(withAttributes: _drawAttributes) ?? CGSize.zero

        var size = CGSize()
        size.width = _labelSize.width + self.insets.left + self.insets.right
        size.height = _labelSize.height + self.insets.top + self.insets.bottom
        size.width = max(minimumSize.width, size.width)
        size.height = max(minimumSize.height, size.height)
        self.size = size
    }
}

Then I add the Balloon marker like below:

let marker:BalloonMarker = BalloonMarker(color: UIColor.black, font: UIFont(name: "Helvetica", size: 12)!, textColor: UIColor.white, insets: UIEdgeInsets(top: 7.0, left: 7.0, bottom: 7.0, right: 7.0))
        marker.minimumSize = CGSize(width: 75.0, height: 35.0)
        chartView.marker = marker

[Edit 1]

There is another method see below, you can consider adding additional data as an AnyObject & get the data value in refreshContent. or you can modify the BalloonMarker class by using dictionary mapping.

 ChartDataEntry(x:Double, y: Double, data: AnyObject?)

Thanks very much, Razib. Give me some time to try this out and I'll report back whether it works or not. — Jim, Apr 16 '18 at 19:08
I'm kind of amazed you were able to do this without the rest of my code. Nice job and thanks again. — Jim, Apr 17 '18 at 13:47
it's my pleasure, last year, I extensively use this chart pod. — Razib Mollick, Apr 17 '18 at 13:51
I'm now studying what you did to learn from it and I see that in the `func draw(context: CGContext, point: CGPoint)` method, you changed `if offset.y > 0` to `if let color = color`. Can you tell me why you changed that? — Jim, Apr 17 '18 at 13:53
I just used their code, did not drive inside like you yet? I guess you don't need all code in your case. — Razib Mollick, Apr 17 '18 at 14:30
Razib, I spoke too soon. I'm taking a closer look at this and I realize the values in the label are still the x and y values. I need to pass in two values that are NOT the x and y values to display them. See my update to the question above. — Jim, Apr 18 '18 at 01:02
Ah I c. How about add a dictionary into BalloonMarker where x value is the key and value is 200? — Razib Mollick, Apr 18 '18 at 01:29
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/169207/discussion-between-jim-and-razib-mollick). — Jim, Apr 18 '18 at 01:32
@Jim , did you check the option ChartDataEntry(x:Double, y: Double, data: AnyObject?) — Razib Mollick, Apr 18 '18 at 20:12
I didn't but that looks promising. I'll see what I can do with it and let you know. — Jim, Apr 19 '18 at 05:07
Razib, that worked! If you'll modify your answer to include your suggestion to use the init that includes the `data:` argument I'll mark it as correct. — Jim, Apr 20 '18 at 05:03

How do I show data other than the chart points (x, y) in a Marker?

1 Answers1