如何为不同的xAxis标签渲染自定义标签颜色？

Question

我正在使用 Charts 库创建一个图表，以在我的应用程序中绘制组合图表。

我成功绘制了图表。现在我想更改特定标签的

xAxis

标签文本颜色。示例如图所示。

如图所示，我想更改特定值的颜色，例如

03/06

和

06/06

。当我在 github 上引用该库时，他们告诉我重写

drawValues()

函数来实现此目的。由于我是快速编程的新手，我不知道如何实现这一点。请指导我如何完成这项任务。预先感谢。

Answer 1

在 XAxisRenderer.swift 内部（不是像建议的其他答案那样的 XAxisRendererHorizontalBarChart），在 drawLabels 函数上方添加带有颜色的列表：

 let labelTextColorList = [UIColor.black, UIColor.red, UIColor.blue, UIColor.brown, UIColor.cyan, UIColor.black, UIColor.black, UIColor.black, UIColor.black, UIColor.black, UIColor.black, UIColor.black]

然后用以下代码替换drawLabels函数：

 /// draws the x-labels on the specified y-position
open func drawLabels(context: CGContext, pos: CGFloat, anchor: CGPoint)
{
    guard
        let xAxis = self.axis as? XAxis,
        let viewPortHandler = self.viewPortHandler,
        let transformer = self.transformer
        else { return }

    #if os(OSX)
        let paraStyle = NSParagraphStyle.default().mutableCopy() as! NSMutableParagraphStyle
    #else
        let paraStyle = NSParagraphStyle.default.mutableCopy() as! NSMutableParagraphStyle
    #endif
    paraStyle.alignment = .center

    //label attrs moved from here
    /*            let labelAttrs = [NSFontAttributeName: xAxis.labelFont,
     NSForegroundColorAttributeName: xAxis.labelTextColor,
     NSParagraphStyleAttributeName: paraStyle] as [String : NSObject]
     */

    let labelRotationAngleRadians = xAxis.labelRotationAngle * ChartUtils.Math.FDEG2RAD

    let centeringEnabled = xAxis.isCenterAxisLabelsEnabled

    let valueToPixelMatrix = transformer.valueToPixelMatrix

    var position = CGPoint(x: 0.0, y: 0.0)

    var labelMaxSize = CGSize()

    if xAxis.isWordWrapEnabled
    {
        labelMaxSize.width = xAxis.wordWrapWidthPercent * valueToPixelMatrix.a
    }

    let entries = xAxis.entries

    for i in stride(from: 0, to: entries.count, by: 1)
    {

        //label attrs moved to here
        let labelAttrs: [String: NSObject]!

        if(i<labelTextColorList.count) {
            labelAttrs = [NSFontAttributeName: xAxis.labelFont,
                                  NSForegroundColorAttributeName: labelTextColorList[i],
                                  NSParagraphStyleAttributeName: paraStyle] as [String : NSObject]
        }
        else {
            labelAttrs = [NSFontAttributeName: xAxis.labelFont,
                          NSForegroundColorAttributeName: xAxis.labelTextColor,
                          NSParagraphStyleAttributeName: paraStyle] as [String : NSObject]

        }
        if centeringEnabled
        {
            position.x = CGFloat(xAxis.centeredEntries[i])
        }
        else
        {
            position.x = CGFloat(entries[i])
        }

        position.y = 0.0
        position = position.applying(valueToPixelMatrix)

        if viewPortHandler.isInBoundsX(position.x)
        {
            let label = xAxis.valueFormatter?.stringForValue(xAxis.entries[i], axis: xAxis) ?? ""

            let labelns = label as NSString

            if xAxis.isAvoidFirstLastClippingEnabled
            {
                // avoid clipping of the last
                if i == xAxis.entryCount - 1 && xAxis.entryCount > 1
                {
                    let width = labelns.boundingRect(with: labelMaxSize, options: .usesLineFragmentOrigin, attributes: labelAttrs, context: nil).size.width

                    if width > viewPortHandler.offsetRight * 2.0
                        && position.x + width > viewPortHandler.chartWidth
                    {
                        position.x -= width / 2.0
                    }
                }
                else if i == 0
                { // avoid clipping of the first
                    let width = labelns.boundingRect(with: labelMaxSize, options: .usesLineFragmentOrigin, attributes: labelAttrs, context: nil).size.width
                    position.x += width / 2.0
                }
            }

            drawLabel(context: context,
                      formattedLabel: label,
                      x: position.x,
                      y: pos,
                      attributes: labelAttrs,
                      constrainedToSize: labelMaxSize,
                      anchor: anchor,
                      angleRadians: labelRotationAngleRadians)
        }
    }
}

结果：

Answer 2

图表库的 XAxisRendererHorizontalBarChart.swift 文件中有以下方法。它将设置 xAxis 的文本。您可以根据您的用例进行自定义。

open override func drawLabels(context: CGContext, pos: CGFloat, anchor: CGPoint)

Answer 3

我的做法是计算 xAxis 的宽度，然后找到标签之间的距离以添加到标签之间

let dateAr = ["3개월 전","2개월 전","1개월 전","현재","1개월 후"] // array,i want to add
let xAixsLabelView = UIView() // view, it will contain labels beneath
let xAxisLabelList = [UILabel(),UILabel(),UILabel(),UILabel(),UILabel()] // array, I will add

.....


func drawXLabel(){
    let color1 = UIColor(red: 0.875, green: 0.875, blue: 0.875, alpha: 1)
    let color2 = BaseViewController().hexStringToUIColor(hex: "#3246FA")

    xAixsLabelView.backgroundColor = .clear
    xAixsLabelView.frame = CGRect(x: lineChartView.frame.minX + 13, y: lineChartView.frame.maxY - 30, width: lineChartView.frame.width , height: 50)
    
    let chartViewWidth = lineChartView.frame.width
    let labelWidth = lineChartView.xAxis.labelWidth
    let paddingWidth = CGFloat((chartViewWidth - (labelWidth * 5))/6) // 5 is the number of labels, and 6 is the number of padding that wraps labels( you need to add 1 to the number of labels 
    
    for i in 0...4{
        
        var padding = paddingWidth * CGFloat(Double(i) + 0.95) + labelWidth * CGFloat(i)
        if i == 0 {
            xAxisLabelList[i].text = "3개월 전"
            xAxisLabelList[i].textColor = color1
            padding = paddingWidth * 1
        }else if i == 1{
            xAxisLabelList[i].text = "2개월 전"
            xAxisLabelList[i].textColor = color1
        }else if i == 2{
            xAxisLabelList[i].text = "1개월 전"
            xAxisLabelList[i].textColor = color1
        }else if i == 3{
            xAxisLabelList[i].text = "현재"
            xAxisLabelList[i].textColor = color2
        }else if i == 4{
            xAxisLabelList[i].text = "1개월 후"
            xAxisLabelList[i].textColor = color1
            padding = paddingWidth * CGFloat(4.7) + labelWidth * CGFloat(i)
        }
                    
        xAxisLabelList[i].font = UIFont(name: "PretendardVariable-Medium", size: 10)
        xAxisLabelList[i].frame = CGRect(x:padding , y:10 , width: labelWidth, height: 18)
       
        
        xAixsLabelView.addSubview(xAxisLabelList[i])
    }
    
    chartView.addSubview(xAixsLabelView)
    chartView.bringSubviewToFront(xAixsLabelView)
    
}

确保这些

• 你要做的是在 lineChartView 上添加视图而不是更改 linechartview 上的 xAxis
• 所有图表都不同，因此请确保偏移量和父视图宽度差异
• 您要添加的列表在 xAxis 中必须相同（长度、文本）
• 确保 xAxis labelColor 中的颜色 .clear