好的,我已经找到了解决方案。对于这样基本的问题来说,它并不像应该那样简单,但是它非常可定制。
LineChartView(通过BarLineChartViewBase)
具有属性xAxisRenderer
。您可以对ChartXAxisRenderer
进行子类化,它是默认的一个,并重写drawLabels
函数。在我的情况下,我复制了原始代码,并修改了在哪里绘制标签以及应该绘制哪个标签的逻辑。
编辑:我的自定义渲染器具有重叠逻辑。可能过于复杂,但目前为止它可以工作。
class ChartXAxisDateRenderer: ChartXAxisRenderer {
internal static let FDEG2RAD = CGFloat(M_PI / 180.0)
override func drawLabels(context context: CGContext, pos: CGFloat, anchor: CGPoint) {
guard let xAxis = xAxis else { return }
let paraStyle = NSParagraphStyle.defaultParagraphStyle().mutableCopy() as! NSMutableParagraphStyle
paraStyle.alignment = .Center
let labelAttrs = [NSFontAttributeName: xAxis.labelFont,
NSForegroundColorAttributeName: xAxis.labelTextColor,
NSParagraphStyleAttributeName: paraStyle]
let labelRotationAngleRadians = xAxis.labelRotationAngle * ChartXAxisDateRenderer.FDEG2RAD
let valueToPixelMatrix = transformer.valueToPixelMatrix
let minLabelsMargin: CGFloat = 4.0
var position = CGPoint(x: 0.0, y: 0.0)
var labelMaxSize = CGSize()
if (xAxis.isWordWrapEnabled) {
labelMaxSize.width = xAxis.wordWrapWidthPercent * valueToPixelMatrix.a
}
var positions = [CGPoint]()
var widths = [CGFloat]()
var labels = [String]()
var originalIndices = [Int]()
for i in 0...xAxis.values.count-1 {
let label = xAxis.values[i]
if (label == nil || label == "")
{
continue
}
originalIndices.append(i)
labels.append(label!)
position.x = CGFloat(i)
position.y = 0.0
position = CGPointApplyAffineTransform(position, valueToPixelMatrix)
positions.append(position)
let labelns = label! as NSString
let width = labelns.boundingRectWithSize(labelMaxSize, options: .UsesLineFragmentOrigin, attributes: labelAttrs, context: nil).size.width
widths.append(width)
}
let newIndices = findBestPositions(positions, widths: widths, margin: minLabelsMargin)
for index in newIndices {
let label = labels[index]
let position = positions[index]
let i = originalIndices[index]
if (viewPortHandler.isInBoundsX(position.x)) {
drawLabel(context: context, label: label, xIndex: i, x: position.x, y: pos, attributes: labelAttrs, constrainedToSize: labelMaxSize, anchor: anchor, angleRadians: labelRotationAngleRadians)
}
}
}
private func findBestPositions(positions: [CGPoint], widths: [CGFloat], margin: CGFloat) -> [Int] {
var n = 1
var overlap = true
while n < widths.count && overlap {
overlap = doesOverlap(n, positions: positions, widths: widths, margin: margin)
if overlap {
n += 1
}
}
var newPositions = [Int]()
var i = 0
while i < positions.count {
newPositions.append(i)
i += n
}
return newPositions
}
private func doesOverlap(n: Int, positions: [CGPoint], widths: [CGFloat], margin: CGFloat) -> Bool {
var i = 0
var newPositions = [CGPoint]()
var newWidths = [CGFloat]()
while i < positions.count {
newPositions.append(positions[i])
newWidths.append(widths[i])
i += n
}
for j in 0...newPositions.count - 2 {
if newPositions[j].x + newWidths[j] + margin > newPositions[j+1].x {
return true
}
}
return false
}
}