左侧双Y轴的曲线对比图表的实现
一、设计图
image.png
image.png
思考:
1.图形两种十分相似，就放一起写了，分为单双轴，x轴坐标数= 单条曲线坐标点数量;
2.单轴共享y轴，也就意味着y轴的坐标点需要由两个曲线数据的最大值决定；
2.双轴的图形分为两条y轴和一条x轴。y轴坐标由各自的最大值决定；
3.双轴y轴有两种刻度，所以两条曲线是分别用各自的坐标系绘制上去的，只是共享了x轴；
4.绘图需要用到贝赛尔曲线和填充渐变色;
5.手势滚动和事件拦截相关逻辑。
二、绘制坐标系
创建坐标点列表
private var points = arrayListOf()
private var points2 = arrayListOf()
override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
super.onSizeChanged(w, h, oldw, oldh)
//计算y轴间隔
yAxisSpace = (measuredHeight - yAxisBottomOffset) / yAxisCount.toFloat()
//计算x轴间隔
xAxisSpace = (measuredWidth - maxYAxisWidth - yAxisLeftOffset) / xAxisCount.toFloat()
var tempX = maxYAxisWidth + yAxisLeftOffset
var tempY = height.toFloat() - yAxisBottomOffset
var tempY2 = tempY
points.clear()
points2.clear()
//添加坐标原点
points.add(PointF(tempX + scrollOffsetX, tempY))
points2.add(PointF(tempX + scrollOffsetX, tempY2))
xArray.forEachIndexed { index, _ ->
//遍历x轴坐标，把坐标点分别计算添加到列表
tempX += xAxisSpace
tempY = OFFSET_CHART_TOP + (height.toFloat() - yAxisBottomOffset - OFFSET_CHART_TOP) * (1 - (yArray[index]) / if (isDouble) yArray.max()!! else maxValue) //yArray.max()!!
tempY2 = OFFSET_CHART_TOP + (height.toFloat() - yAxisBottomOffset - OFFSET_CHART_TOP) * (1 - (yArray2[index]) / if (isDouble) yArray2.max()!! else maxValue) //yArray2.max()!!
points.add(PointF(tempX + scrollOffsetX, tempY))
points2.add(PointF(tempX + scrollOffsetX, tempY2))
}
....
}
override fun onDraw(canvas: Canvas?) {
super.onDraw(canvas)
var yUsed = height.toFloat() - yAxisBottomOffset
val xUsed = maxYAxisWidth + yAxisLeftOffset
//x坐标
textPaint.color = Color.BLACK
textPaint.textAlign = Paint.Align.CENTER
xArray.forEachIndexed { index, it ->
canvas?.drawText(it, points[index + 1].x - scrollOffsetX, height.toFloat(), textPaint)
}
canvas?.drawLine(xUsed, yUsed, max(points.last().x + xUsed, width.toFloat()), yUsed, textPaint)
//y坐标
textPaint.textAlign = Paint.Align.RIGHT
canvas?.drawLine(xUsed, yUsed, xUsed, 0f, textPaint)
for (i in 0 until yAxisCount) {
//如果是双Y轴则分别用各自最大值计算Y坐标，否则用两者最大值计算
if (isDouble) {
textPaint.color = color
canvas?.drawText((i / yAxisCount.toFloat() * yArray.max()!!).toString(), maxYAxisWidth, yUsed, textPaint)
textPaint.color = color2
canvas?.drawText((i / yAxisCount.toFloat() * yArray2.max()!!).toString(), maxYAxisWidth - yArrayWordWidth, yUsed, textPaint)
} else {
canvas?.drawText((i / yAxisCount.toFloat() * maxValue).toString(), maxYAxisWidth, yUsed, textPaint)
}
yUsed -= yAxisSpace
}
}
坐标系便绘制好了
坐标系
三、绘制坐曲线和坐标点
贝塞尔曲线分为二次(quadTo)和三次(cubicTo)贝塞尔曲线，这里需要把坐标连贯穿过，就选择三次贝塞尔曲线实现。
光滑曲线必定处处可导。
示例图
A2和B1就是三次贝赛尔曲线的控制点，其连线是曲线的切线，切点为A3。其中，令A0和B3连线的斜率 = A2和B1连线的斜率，可以让曲线过度更自然。
那么
令
A0和B3连线的斜率 k = (B3Y - A0Y) / (B3X - A0X)
常数 b = A3Y - k * A3X
则
A2的X坐标 A2X = A3X - (A3X - A0X) * rate
A2的Y坐标 A2Y = k * A2X + b
B1的X坐标 B1X = A3X + (B3X - A3X) * rate
B1的Y坐标 B1Y = k * B1X + b
rate 一般取(0,0.5)。
除此以外，如果数值点是第一个点或者最后一个点，可以把斜率k视为0，然后只计算左控制点或者右控制点。
先穿越看看rate取[0,1]对曲线的影响:
rate对曲线的影响
所以这个rate是当前点到两侧点的距离因子，如果大于0.5f会使曲度过大，导致曲线变形不利于观看。
1.计算控制点坐标
/**
* 计算控制点坐标
* @param pointList 坐标点列表
* @param controlPoints 控制点坐标(空列表)
*/
private fun calculateControlPoint(pointList: List, controlPoints: ArrayList) {
controlPoints.clear()
if (pointList.size <= 1) {
return
}
for ((i, point) in pointList.withIndex()) {
when (i) {
0 -> {//第一项
//添加后控制点
val nextPoint = pointList[i + 1]
val controlX = point.x + (nextPoint.x - point.x) * SMOOTHNESS
val controlY = point.y
controlPoints.add(PointF(controlX, controlY))
}
pointList.size - 1 -> {//最后一项
//添加前控制点
val lastPoint = pointList[i - 1]
val controlX = point.x - (point.x - lastPoint.x) * SMOOTHNESS
val controlY = point.y
controlPoints.add(PointF(controlX, controlY))
}
else -> {//中间项
val lastPoint = pointList[i - 1]
val nextPoint = pointList[i + 1]
val k = (nextPoint.y - lastPoint.y) / (nextPoint.x - lastPoint.x)
val b = point.y - k * point.x
//添加前控制点
val lastControlX = point.x - (point.x - lastPoint.x) * SMOOTHNESS
val lastControlY = k * lastControlX + b
controlPoints.add(PointF(lastControlX, lastControlY))
//添加后控制点
val nextControlX = point.x + (nextPoint.x - point.x) * SMOOTHNESS
val nextControlY = k * nextControlX + b
controlPoints.add(PointF(nextControlX, nextControlY))
}
}
}
}
/**
* 绘制曲线、坐标以及填充渐变色
*/
private fun Canvas.linkPath(path: Path, maxHeight: Float, points: ArrayList, controlPoints: ArrayList, paint: Paint, color: Int) {
//连接各部分曲线
path.reset()
val firstPoint = points.first()
path.moveTo(firstPoint.x - scrollOffsetX, firstPoint.y)
path.lineTo(firstPoint.x - scrollOffsetX, firstPoint.y)
for (i in 0 until ((points.size - 1) * 2) step 2) {
val leftControlPoint = controlPoints[i]
val rightControlPoint = controlPoints[i + 1]
val rightPoint = points[i / 2 + 1]
path.cubicTo(
leftControlPoint.x - scrollOffsetX,
leftControlPoint.y,
rightControlPoint.x - scrollOffsetX,
rightControlPoint.y,
rightPoint.x - scrollOffsetX, rightPoint.y)
}
val lastPoint = points.last()
//填充渐变色
path.lineTo(lastPoint.x - scrollOffsetX, lastPoint.y)
path.lineTo(firstPoint.x - scrollOffsetX, maxHeight + OFFSET_CHART_TOP)
paint.alpha = 130
paint.style = Paint.Style.FILL
paint.shader = LinearGradient(0F, 0F, 0F,
maxHeight, color, Color.WHITE, Shader.TileMode.CLAMP)
drawPath(path, paint)
//绘制全部路径
path.setLastPoint(lastPoint.x - scrollOffsetX, lastPoint.y)
paint.strokeWidth = SIZE_LINE
paint.style = Paint.Style.STROKE
paint.shader = null
paint.color = color
drawPath(path, paint)
for (i in 0 until points.size) {
val point = points[i]
//画数值点
paint.style = Paint.Style.FILL
paint.alpha = 255
paint.color = Color.WHITE
drawCircle(point.x - scrollOffsetX, point.y, SIZE_POINT, paint)
paint.strokeWidth = 3f
paint.style = Paint.Style.STROKE
paint.color = color
drawCircle(point.x - scrollOffsetX, point.y, SIZE_POINT, paint)
}
}
override fun onDraw(canvas: Canvas?) {
super.onDraw(canvas)
var yUsed = height.toFloat() - yAxisBottomOffset
val xUsed = maxYAxisWidth + yAxisLeftOffset
...
linePaint.color = color
canvas?.linkPath(
path = linePath,
maxHeight = yUsed - OFFSET_CHART,
points = mPoints,
controlPoints = mControlPointList,
paint = linePaint,
color = linePaint.color
)
linePaint.color = color2
canvas?.linkPath(
path = linePath,
maxHeight = yUsed - OFFSET_CHART,
points = mPoints2,
controlPoints = mControlPointList2,
paint = linePaint,
color = linePaint.color
)
...
}
绘制完成如下:
绘制完成示例图
四、添加手势滑动
此图只需要左右滑动，所以添加scrollOffsetX字段用于控制滚动偏移量。利用OverScroller和GestureDetector做一个可以回弹的滚动，如下：
override fun onTouchEvent(event: MotionEvent?): Boolean {
...
return gestureDetector.onTouchEvent(event)
}
inner class MyOnGestureListener : GestureDetector.OnGestureListener {
private val maxOffset by lazy { points2.last().x.toInt() - (width - maxYAxisWidth.toInt()) }
override fun onShowPress(e: MotionEvent?) {}
override fun onSingleTapUp(e: MotionEvent?): Boolean = false
override fun onDown(e: MotionEvent?): Boolean = true
override fun onFling(e1: MotionEvent?, e2: MotionEvent?, velocityX: Float, velocityY: Float): Boolean {
scroller.fling(scrollOffsetX.toInt(), 0, - velocityX.toInt(), 0, 0,
maxOffset, 0, 0, 200, 0)
ViewCompat.postOnAnimation(this@LineChart, scrollRunnable)
return false
}
override fun onScroll(e1: MotionEvent?, e2: MotionEvent?, distanceX: Float, distanceY: Float): Boolean {
scrollOffsetX += distanceX
invalidate()
return false
}
override fun onLongPress(e: MotionEvent?) {}
}
inner class MyScrollRunnable : Runnable {
override fun run() {
if (scroller.computeScrollOffset()) {
scrollOffsetX = scroller.currX.toFloat()
invalidate()
ViewCompat.postOnAnimation(this@LineChart, scrollRunnable)
}
}
}
弹性滑动添加完毕,处理应用出现的问题:
1.向左滑动会导致曲线覆盖Y轴:
用clipRect在绘制曲线的时候剪切下来再绘制。
canvas?.save()
canvas?.clipRect(xUsed.toInt(), 0, width, height)
linePaint.color = color
canvas?.linkPath(
path = linePath,
maxHeight = yUsed - OFFSET_CHART_TOP,
points = points,
controlPoints = controlPointList,
paint = linePaint,
color = linePaint.color
)
linePaint.color = color2
canvas?.linkPath(
path = linePath,
maxHeight = yUsed - OFFSET_CHART_TOP,
points = points2,
controlPoints = controlPointList2,
paint = linePaint,
color = linePaint.color
)
canvas?.restore()
2.嵌套ScrollView的滑动冲突:
当是我们需要处理的横向滚动时，让parent不拦截事件
override fun onTouchEvent(event: MotionEvent?): Boolean {
when (event?.actionMasked) {
MotionEvent.ACTION_DOWN -> {
mDownX = event.x
mDownY = event.y
}
MotionEvent.ACTION_MOVE -> {
if (abs(mDownY - event.y) < abs(mDownX - event.x))
parent.requestDisallowInterceptTouchEvent(true)
}
}
return gestureDetector.onTouchEvent(event)
}
3.滑动->停止->抬手导致不会弹问题:
添加手指抬起判断，手指抬起没有滑动的时候，让视图滚动(offset)到设定的边值界。
MotionEvent.ACTION_UP -> {
if (scrollOffsetX != 0f && !scroller.computeScrollOffset()) {
gestureListener.onFling(null, null, if (scrollOffsetX < 0f) -20f else 20f, 0f)
}
}
五、完整代码和完成效果
package com.zhtx.business.widget
import android.content.Context
import android.content.res.Resources
import android.graphics.*
import android.support.v4.view.ViewCompat
import android.util.AttributeSet
import android.util.TypedValue
import android.view.GestureDetector
import android.view.MotionEvent
import android.view.View
import android.view.animation.AccelerateDecelerateInterpolator
import android.widget.OverScroller
import kotlin.math.abs
import kotlin.math.max
class LineChart : View {
companion object{
//平滑度
const val SMOOTHNESS = 0.39f
//描点大小
const val SIZE_POINT = 15f
//线条宽度
const val SIZE_LINE = 10f
//图表顶部偏移
const val OFFSET_CHART_TOP = 60f
fun Float.sp2px() = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, this, Resources.getSystem().displayMetrics)
fun Float.dp2px() = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, this, Resources.getSystem().displayMetrics)
}
//右轴坐标数量
private val yAxisCount = 10
//x轴坐标数量
private val xAxisCount = 5
//文本画笔
private val textPaint = Paint(Paint.ANTI_ALIAS_FLAG)
//y轴间隔
private var yAxisSpace = 0f
//x轴间隔
private var xAxisSpace = 0f
//是否是双Y轴
private var isDouble = false
//数据一
private var yArray = arrayListOf()
//数据二
private var yArray2 = arrayListOf()
//x轴坐标数据
private var xArray = arrayListOf()
//y轴底部偏移量
private var yAxisBottomOffset = 0f
//x轴左侧偏移量
private var yAxisLeftOffset = 10f
private var maxYAxisWidth = 0f
private val linePath = Path()
private var controlPointList = arrayListOf()
private var controlPointList2 = arrayListOf()
private var points = arrayListOf()
private var points2 = arrayListOf()
private val color by lazy { Color.parseColor("#614DB6") }
private val color2 by lazy { Color.parseColor("#FC5C7D") }
private val linePaint = Paint(Paint.ANTI_ALIAS_FLAG)
//数组1的Y轴文字宽度
private var yArrayWordWidth = 0f
private var maxValue = 0f
private val gestureListener by lazy { MyOnGestureListener() }
private val gestureDetector by lazy { GestureDetector(context, gestureListener) }
private val scroller by lazy { OverScroller(context, AccelerateDecelerateInterpolator()) }
private var scrollOffsetX = 0f
private val scrollRunnable = MyScrollRunnable()
constructor(context: Context) : super(context)
constructor(context: Context, attributeSet: AttributeSet) : super(context, attributeSet)
constructor(context: Context, attributeSet: AttributeSet, defStyle: Int) : super(context, attributeSet, defStyle)
init {
init()
}
private fun init() {
maxValue = max(yArray.max() ?: 0f, yArray2.max() ?: 0f)
textPaint.textSize = 12f.sp2px()
textPaint.textAlign = Paint.Align.LEFT
yArrayWordWidth = textPaint.measureText(yArray.max().toString())
maxYAxisWidth = if (isDouble) yArrayWordWidth + textPaint.measureText(yArray2.max().toString()) else textPaint.measureText(maxValue.toString())
textPaint.color = Color.BLACK
textPaint.strokeWidth = 2f
yAxisBottomOffset = textPaint.fontMetrics.bottom - textPaint.fontMetrics.top
linePaint.apply {
strokeWidth = 3f
style = Paint.Style.STROKE
isDither = true
}
}
fun setDataArray(xArrAy: ArrayList, yArray: ArrayList, yArray2: ArrayList) {
this.xArray = xArrAy
this.yArray = yArray
this.yArray2 = yArray2
init()
measureChild()
invalidate()
}
override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
super.onSizeChanged(w, h, oldw, oldh)
measureChild()
}
private fun measureChild() {
//计算y轴间隔
yAxisSpace = (measuredHeight - yAxisBottomOffset) / yAxisCount.toFloat()
//计算x轴间隔
xAxisSpace = (measuredWidth - maxYAxisWidth - yAxisLeftOffset) / xAxisCount.toFloat()
var tempX = maxYAxisWidth + yAxisLeftOffset
var tempY = height.toFloat() - yAxisBottomOffset
var tempY2 = tempY
points.clear()
points2.clear()
//添加坐标原点
points.add(PointF(tempX + scrollOffsetX, tempY))
points2.add(PointF(tempX + scrollOffsetX, tempY2))
//遍历x轴坐标，把坐标点分别计算添加到列表
xArray.forEachIndexed { index, _ ->
tempX += xAxisSpace
tempY = OFFSET_CHART_TOP + (height.toFloat() - yAxisBottomOffset - OFFSET_CHART_TOP) * (1 - (yArray[index]) / if (isDouble) yArray.max()!! else maxValue) //yArray.max()!!
tempY2 = OFFSET_CHART_TOP + (height.toFloat() - yAxisBottomOffset - OFFSET_CHART_TOP) * (1 - (yArray2[index]) / if (isDouble) yArray2.max()!! else maxValue) //yArray2.max()!!
points.add(PointF(tempX + scrollOffsetX, tempY))
points2.add(PointF(tempX + scrollOffsetX, tempY2))
}
//计算控制点
calculateControlPoint(points, controlPointList)
calculateControlPoint(points2, controlPointList2)
}
override fun onDraw(canvas: Canvas?) {
super.onDraw(canvas)
var yUsed = height.toFloat() - yAxisBottomOffset
val xUsed = maxYAxisWidth + yAxisLeftOffset
canvas?.save()
canvas?.clipRect(xUsed.toInt(), 0, width, height)
linePaint.color = color
canvas?.linkPath(
path = linePath,
maxHeight = yUsed - OFFSET_CHART_TOP,
points = points,
controlPoints = controlPointList,
paint = linePaint,
color = linePaint.color
)
linePaint.color = color2
canvas?.linkPath(
path = linePath,
maxHeight = yUsed - OFFSET_CHART_TOP,
points = points2,
controlPoints = controlPointList2,
paint = linePaint,
color = linePaint.color
)
canvas?.restore()
//x坐标
textPaint.color = Color.BLACK
textPaint.textAlign = Paint.Align.CENTER
xArray.forEachIndexed { index, it ->
canvas?.drawText(it, points[index + 1].x - scrollOffsetX, height.toFloat(), textPaint)
}
canvas?.drawLine(xUsed, yUsed, max(points.last().x + xUsed, width.toFloat()), yUsed, textPaint)
//y坐标
textPaint.textAlign = Paint.Align.RIGHT
canvas?.drawLine(xUsed, yUsed, xUsed, 0f, textPaint)
for (i in 0 until yAxisCount) {
//如果是双Y轴则分别用各自最大值计算Y坐标，否则用两者最大值计算
if (isDouble) {
textPaint.color = color
canvas?.drawText((i / yAxisCount.toFloat() * yArray.max()!!).toString(), maxYAxisWidth, yUsed, textPaint)
textPaint.color = color2
canvas?.drawText((i / yAxisCount.toFloat() * yArray2.max()!!).toString(), maxYAxisWidth - yArrayWordWidth, yUsed, textPaint)
} else {
canvas?.drawText((i / yAxisCount.toFloat() * maxValue).toString(), maxYAxisWidth, yUsed, textPaint)
}
yUsed -= yAxisSpace
}
}
/**
* 计算控制点坐标
* @param pointList 坐标点列表
* @param controlPoints 控制点坐标(空列表)
*/
private fun calculateControlPoint(pointList: List, controlPoints: ArrayList) {
controlPoints.clear()
if (pointList.size <= 1) {
return
}
for ((i, point) in pointList.withIndex()) {
when (i) {
0 -> {//第一项
//添加后控制点
val nextPoint = pointList[i + 1]
val controlX = point.x + (nextPoint.x - point.x) * SMOOTHNESS
val controlY = point.y
controlPoints.add(PointF(controlX, controlY))
}
pointList.size - 1 -> {//最后一项
//添加前控制点
val lastPoint = pointList[i - 1]
val controlX = point.x - (point.x - lastPoint.x) * SMOOTHNESS
val controlY = point.y
controlPoints.add(PointF(controlX, controlY))
}
else -> {//中间项
val lastPoint = pointList[i - 1]
val nextPoint = pointList[i + 1]
val k = (nextPoint.y - lastPoint.y) / (nextPoint.x - lastPoint.x)
val b = point.y - k * point.x
//添加前控制点
val lastControlX = point.x - (point.x - lastPoint.x) * SMOOTHNESS
val lastControlY = k * lastControlX + b
controlPoints.add(PointF(lastControlX, lastControlY))
//添加后控制点
val nextControlX = point.x + (nextPoint.x - point.x) * SMOOTHNESS
val nextControlY = k * nextControlX + b
controlPoints.add(PointF(nextControlX, nextControlY))
}
}
}
}
/**
* 绘制曲线、坐标以及填充渐变色
*/
private fun Canvas.linkPath(path: Path, maxHeight: Float, points: ArrayList, controlPoints: ArrayList, paint: Paint, color: Int) {
//连接各部分曲线
path.reset()
val firstPoint = points.first()
path.moveTo(firstPoint.x - scrollOffsetX, firstPoint.y)
path.lineTo(firstPoint.x - scrollOffsetX, firstPoint.y)
for (i in 0 until ((points.size - 1) * 2) step 2) {
val leftControlPoint = controlPoints[i]
val rightControlPoint = controlPoints[i + 1]
val rightPoint = points[i / 2 + 1]
path.cubicTo(
leftControlPoint.x - scrollOffsetX,
leftControlPoint.y,
rightControlPoint.x - scrollOffsetX,
rightControlPoint.y,
rightPoint.x - scrollOffsetX, rightPoint.y)
}
val lastPoint = points.last()
//填充渐变色
path.lineTo(lastPoint.x - scrollOffsetX, lastPoint.y)
path.lineTo(firstPoint.x - scrollOffsetX, maxHeight + OFFSET_CHART_TOP)
paint.alpha = 130
paint.style = Paint.Style.FILL
paint.shader = LinearGradient(0F, 0F, 0F,
maxHeight, color, Color.WHITE, Shader.TileMode.CLAMP)
drawPath(path, paint)
//绘制全部路径
path.setLastPoint(lastPoint.x - scrollOffsetX, lastPoint.y)
paint.strokeWidth = SIZE_LINE
paint.style = Paint.Style.STROKE
paint.shader = null
paint.color = color
drawPath(path, paint)
for (i in 0 until points.size) {
val point = points[i]
//画数值点
paint.style = Paint.Style.FILL
paint.alpha = 255
paint.color = Color.WHITE
drawCircle(point.x - scrollOffsetX, point.y, SIZE_POINT, paint)
paint.strokeWidth = 3f
paint.style = Paint.Style.STROKE
paint.color = color
drawCircle(point.x - scrollOffsetX, point.y, SIZE_POINT, paint)
}
}
private var mDownX = 0f
private var mDownY = 0f
override fun onTouchEvent(event: MotionEvent?): Boolean {
when (event?.actionMasked) {
MotionEvent.ACTION_DOWN -> {
mDownX = event.x
mDownY = event.y
}
MotionEvent.ACTION_MOVE -> {
if (abs(mDownY - event.y) < abs(mDownX - event.x))
parent.requestDisallowInterceptTouchEvent(true)
}
MotionEvent.ACTION_UP -> {
if (scrollOffsetX != 0f && !scroller.computeScrollOffset()) {
gestureListener.onFling(null, null, if (scrollOffsetX < 0f) -20f else 20f, 0f)
}
}
}
return gestureDetector.onTouchEvent(event)
}
inner class MyOnGestureListener : GestureDetector.OnGestureListener {
private val maxOffset by lazy { points2.last().x.toInt() - (width - maxYAxisWidth.toInt()) }
override fun onShowPress(e: MotionEvent?) {}
override fun onSingleTapUp(e: MotionEvent?): Boolean = false
override fun onDown(e: MotionEvent?): Boolean = true
override fun onFling(e1: MotionEvent?, e2: MotionEvent?, velocityX: Float, velocityY: Float): Boolean {
scroller.fling(scrollOffsetX.toInt(), 0, - velocityX.toInt(), 0, 0,
maxOffset, 0, 0, 200, 0)
ViewCompat.postOnAnimation(this@LineChart, scrollRunnable)
return false
}
override fun onScroll(e1: MotionEvent?, e2: MotionEvent?, distanceX: Float, distanceY: Float): Boolean {
scrollOffsetX += distanceX
invalidate()
return false
}
override fun onLongPress(e: MotionEvent?) {}
}
inner class MyScrollRunnable : Runnable {
override fun run() {
if (scroller.computeScrollOffset()) {
scrollOffsetX = scroller.currX.toFloat()
invalidate()
ViewCompat.postOnAnimation(this@LineChart, scrollRunnable)
}
}
}
}
完成效果
github
六、参考文档
Android艺术之画一条平滑的曲线