带有 ios-charts 库的 Swift，如何在 BarChart 中设置条形上方图标的大小？

Question

使用图表库，我有一个视图，其中显示图像或名称的首字母直到插入的数据。我想将此视图用作条形顶部的图像。由于它不是一个时代，我必须通过自定义方法将其转换为 UIImage，因为 Icon 不接受 Views bu only images。

如果我尝试更改帧值，我无法理解我想要的原因，圆形视图会更小一些，在这种情况下，条的大小相同，而不是“偏心”。

left：起始情况（圆圈略大于条的宽度） 右：更改 I.E. 后宽高52

我的自定义视图有这段代码，我认为这里可能有用（给定内在内容大小，无法更改）：

public var model: BrandViewModel! { didSet { self.updateOutlets() } }
open override var intrinsicContentSize: CGSize { CGSize(width: 72, height: 72) }


open override func configure() {
    
    super.configure()
    
    self.backgroundColor = .white
    self.layer.cornerRadius = self.intrinsicContentSize.width / 2
    self.imageView.layer.cornerRadius = self.imageView.bounds.width / 2
    self.initialsContainer.layer.cornerRadius = self.imageView.layer.cornerRadius
    
    self.setupShadow()
}

我的图表类：

public struct BarChartValue {
    public var value: Double?
    public var name: String?
    public var color: UIColor?
    
    public init(value: Double?, name: String?, color: UIColor?) {
        self.value = value
        self.name = name
        self.color = color
    }
}

public class CorporateBarChartView: BarChartView {
    
    public override func awakeFromNib() {
        super.awakeFromNib()
        self.setup()
    }
    
    public var values: [BarChartValue]? {
        willSet {
            self.setDataCount(withValues: newValue)
        }
    }
    
    private func setup() {
        self.chartDescription.enabled = false
        self.highlightPerTapEnabled = false
        self.legend.enabled = false
        self.drawBarShadowEnabled = false
        self.drawValueAboveBarEnabled = false
        self.leftAxis.enabled = false
        self.rightAxis.enabled = false
        self.xAxis.enabled = false
        self.pinchZoomEnabled = false
        self.doubleTapToZoomEnabled = false
        self.leftAxis.axisMinimum = 0
        self.isUserInteractionEnabled = false
    }
    
    func setDataCount(withValues values: [BarChartValue]?) {
        guard let values = values else { return }
        let silverPlaceholder = UIColor.gray.withAlphaComponent(0.2)
        
        let dataEntries = values.enumerated().map({ (index, value) -> BarChartDataEntry in
            let brandView = BrandView()
            brandView.model = BrandViewModel(name: value.name, image: nil)
            let view = UIView(frame: CGRect(x: 0, y: 0, width: 72, height: 72))
            view.addSubview(brandView)
            view.backgroundColor = .red//.clear
            brandView.backgroundColor = .green//.clear
            let image = self.image(with: view)
            return BarChartDataEntry(x: Double(index), y: value.value ?? 0, icon: image)
        })
        var set: BarChartDataSet! = nil
        set = BarChartDataSet(entries: dataEntries)
        set.colors = values.map({ (model) -> NSUIColor in
            return (model.color ?? silverPlaceholder)
        })
        set.drawValuesEnabled = false
        
        let data = BarChartData(dataSet: set)
        data.barWidth = 0.3
        self.data = data
    }
    
    func image(with view: UIView) -> UIImage? {
        UIGraphicsBeginImageContextWithOptions(view.bounds.size, false, 0.0)
        defer { UIGraphicsEndImageContext() }
        if let context = UIGraphicsGetCurrentContext() {
            view.layer.render(in: context)
            let image = UIGraphicsGetImageFromCurrentImageContext()
            return image
        }
        return nil
    }
}

Answer 1

1. 为什么必须将brandView 包装到另一个view 中？如果你这样做，那么你必须确保它的布局正确或设置了正确的框架。我还建议重用视图的一个实例，这意味着我会在 dataEntries 之前创建一次，然后用新数据重新配置它以生成新图像。
2. 我想您必须将图像调整为所需的大小，以便图表可以正确绘制它。为此，您可以使用以下扩展：

extension UIImage {

    func scaled(toWidth width: CGFloat) -> UIImage? {

        guard width > 0.0, self.size.width > 0.0 else {
            return nil
        }

        return self.redrawnImage(with: self.size.scaled(toWidth: width))
    }

    func scaled(toHeight height: CGFloat) -> UIImage? {

        guard height > 0.0, self.size.height > 0.0 else {
            return nil
        }

        return self.redrawnImage(with: self.size.scaled(toHeight: height))
    }

    private func redrawnImage(with size: CGSize) -> UIImage {

        UIGraphicsImageRenderer(size: size).image { _ in
            draw(in: .init(origin: .zero, size: size))
        }
    }
}

extension CGSize {

    func scaled(toWidth width: CGFloat) -> CGSize {
        CGSize(width: width, height: (self.height / self.width) * width)
    }

    func scaled(toHeight height: CGFloat) -> CGSize {
        CGSize(width: (self.width / self.height) * height, height: height)
    }
}