在没有第三方库的情况下，用Kotlin绘制简单的XY图

Question

我想使用从JSON解析的数据绘制一个简单的XY图，但这里的每个答案都重定向到使用某种库。我想在不使用任何库的情况下绘制它，有没有可能在Kotlin中做到这一点？

PS不，这不是家庭作业或smth。

Answer 1

有一种简单的方法可以通过编写自定义视图来集成图形

(原件：https://github.com/SupahSoftware/AndroidExampleGraphView(

import android.content.Context
import android.graphics.Canvas
import android.graphics.Color
import android.graphics.Paint
import android.util.AttributeSet
import android.view.View
class GraphView(context: Context, attributeSet: AttributeSet) : View(context, attributeSet) {
private val dataSet = mutableListOf<DataPoint>()
private var xMin = 0
private var xMax = 0
private var yMin = 0
private var yMax = 0
private val dataPointPaint = Paint().apply {
color = Color.BLUE
strokeWidth = 7f
style = Paint.Style.STROKE
}
private val dataPointFillPaint = Paint().apply {
color = Color.WHITE
}
private val dataPointLinePaint = Paint().apply {
color = Color.BLUE
strokeWidth = 7f
isAntiAlias = true
}
private val axisLinePaint = Paint().apply {
color = Color.RED
strokeWidth = 10f
}
fun setData(newDataSet: List<DataPoint>) {
xMin = newDataSet.minBy { it.xVal }?.xVal ?: 0
xMax = newDataSet.maxBy { it.xVal }?.xVal ?: 0
yMin = newDataSet.minBy { it.yVal }?.yVal ?: 0
yMax = newDataSet.maxBy { it.yVal }?.yVal ?: 0
dataSet.clear()
dataSet.addAll(newDataSet)
invalidate()
}
override fun onDraw(canvas: Canvas) {
super.onDraw(canvas)
dataSet.forEachIndexed { index, currentDataPoint ->
val realX = currentDataPoint.xVal.toRealX()
val realY = currentDataPoint.yVal.toRealY()
if (index < dataSet.size - 1) {
val nextDataPoint = dataSet[index + 1]
val startX = currentDataPoint.xVal.toRealX()
val startY = currentDataPoint.yVal.toRealY()
val endX = nextDataPoint.xVal.toRealX()
val endY = nextDataPoint.yVal.toRealY()
canvas.drawLine(startX, startY, endX, endY, dataPointLinePaint)
}
canvas.drawCircle(realX, realY, 7f, dataPointFillPaint)
canvas.drawCircle(realX, realY, 7f, dataPointPaint)
}
canvas.drawLine(0f, 0f, 0f, height.toFloat(), axisLinePaint)
canvas.drawLine(0f, height.toFloat(), width.toFloat(), height.toFloat(), axisLinePaint)
}
private fun Int.toRealX() = toFloat() / xMax * width
private fun Int.toRealY() = toFloat() / yMax * height
}
data class DataPoint(
val xVal: Int,
val yVal: Int
)