Question

我使用Charts库创建图表，在我的应用中绘制组合图表。

我成功绘制了图表。现在我想更改特定标签的xAxis标签文字颜色。示例显示在图片

中

如图所示，我想更改特定值的颜色，例如03/06＆amp; 06/06。当我在github上引用库时，他们告诉我覆盖drawValues()函数来实现这一点。作为我快速编程的新手，我不知道如何实现这一目标。请指导我如何完成这项任务。提前谢谢。

Answer 1

图表库的XAxisRendererHorizontalBarChart.swift文件中有以下方法。它将为xAxis设置文本。您可以根据用例自定义它。

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

Answer 2

在XAxisRenderer.swift（不是XAxisRendererHorizontalBarChart，如同建议的其他答案）中添加此列表，其颜色与drawLabels函数相同：

 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：

如何为不同的xAxis标签呈现自定义标签颜色？

2 个答案: