Custom X Axis for BarChartView - ios

Question

I am using BarChartView from danielgindi/ios-charts charting library. So far I am able to get following BarChartView. My question, is there any way to Customize X Axis that way, it will only show min (left most value 37.03), max (right most value 37.31 which is hiding), value for green bar (37.17) and value for orange bar (37.18 which is hiding again). In a nutshell I want to hide some value from XAxis which is not important in my case.

Answer 1

This is an example: add a property called showOnlyLeftRightEnabled in YourChartXAxis class, then in your custom x axis renderer, overide internal override func drawLabels(context context: CGContext, pos: CGFloat, anchor: CGPoint).
To display the middle one's you need to figure out which bar it is, and convert the x Index to pixel values just like what I did for the left most and right most value via CGPointApplyAffineTransform(position, valueToPixelMatrix)
internal override func drawLabels(context context: CGContext, pos: CGFloat, anchor: CGPoint)
{
let paraStyle = NSParagraphStyle.defaultParagraphStyle().mutableCopy() as! NSMutableParagraphStyle
paraStyle.alignment = .Center
let labelAttrs = [NSFontAttributeName: _xAxis.labelFont,
NSForegroundColorAttributeName: _xAxis.labelTextColor,
NSParagraphStyleAttributeName: paraStyle]
let labelRotationAngleRadians = _xAxis.labelRotationAngle * ChartUtils.Math.FDEG2RAD
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
}
if let showOnlyLeftRight = (_xAxis as? YourChartXAxis)?.showOnlyLeftRightEnabled
{
if (showOnlyLeftRight)
{
for (var i = lowestVisibleXIndex, maxX = min(highestVisibleXIndex + 1, _xAxis.values.count); i < maxX; i += maxX - lowestVisibleXIndex - 1)
{
let label = _xAxis.values[i]
if (label == nil)
{
continue
}
position.x = CGFloat(i)
position.y = 0.0
position = CGPointApplyAffineTransform(position, valueToPixelMatrix)
let labelns = label! as NSString
//label location by string width
// fix rightLabel
if (highestVisibleXIndex == lowestVisibleXIndex)
{
return super.drawLabels(context: context, pos: pos, anchor: anchor)
}
else if (i == highestVisibleXIndex)
{
let width = labelns.boundingRectWithSize(labelMaxSize, options: .UsesLineFragmentOrigin, attributes: labelAttrs, context: nil).size.width
rightLabelX -= width / 2.0
}
else if (i == lowestVisibleXIndex)
{ // fix leftLabel
let width = labelns.boundingRectWithSize(labelMaxSize, options: .UsesLineFragmentOrigin, attributes: labelAttrs, context: nil).size.width
leftLabelX += width / 2.0
}
// fill leftLabel and rightLabel in current visible screen
if (lowestVisibleXIndex == highestVisibleXIndex) {
ChartUtils.drawMultilineText(context: context, text: label!, point: CGPoint(x: leftLabelX, y: pos), attributes: labelAttrs, constrainedToSize: labelMaxSize, anchor: anchor, angleRadians: labelRotationAngleRadians)
ChartUtils.drawMultilineText(context: context, text: label!, point: CGPoint(x: rightLabelX, y: pos), attributes: labelAttrs, constrainedToSize: labelMaxSize, anchor: anchor, angleRadians: labelRotationAngleRadians)
break
} else if (i == lowestVisibleXIndex) {
ChartUtils.drawMultilineText(context: context, text: label!, point: CGPoint(x: leftLabelX, y: pos), attributes: labelAttrs, constrainedToSize: labelMaxSize, anchor: anchor, angleRadians: labelRotationAngleRadians)
} else if (i == highestVisibleXIndex) {
ChartUtils.drawMultilineText(context: context, text: label!, point: CGPoint(x: rightLabelX, y: pos), attributes: labelAttrs, constrainedToSize: labelMaxSize, anchor: anchor, angleRadians: labelRotationAngleRadians)
}
}
} else {
super.drawLabels(context: context, pos: pos, anchor: anchor)
}
}
}