[lb11] DrawSurface.kt

package com.example.lb11

import android.content.Context
import android.graphics.Canvas
import android.graphics.Color
import android.graphics.Paint
import android.graphics.Rect
import android.util.AttributeSet
import android.view.SurfaceHolder
import android.view.SurfaceView
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.Job
import kotlinx.coroutines.launch
import kotlin.math.PI
import kotlin.math.cos
import kotlin.math.sin

class DrawSurface : SurfaceView, SurfaceHolder.Callback {

    private var cx = 0f


    private var paint = Paint()
    private lateinit var job: Job

    private var r: Float = 50F
    private var h = 3*r
    private var l = 7*r
    private var l2 = 11*r
    private var dx = 10f
    private var dy: Float = h+r
    private var df = 2f
    private var f = 0f

    private var cy = 0f

    private var cx2 = 0f
    private var cy2 = 0f
    private var dx2 = 10f
    private var dy2 = 10f
    private var r2 = 5f

    constructor(context: Context) : this(context, null)
    constructor(context: Context, attrs: AttributeSet?) : this(context, attrs, 0)
    constructor(context: Context, attrs: AttributeSet?,
                defStyleAttr: Int) : super(context, attrs, defStyleAttr) {}
    override fun surfaceChanged(holder: SurfaceHolder, format: Int,
                                width: Int, height: Int) {
    }
    override fun surfaceCreated(holder: SurfaceHolder) {
        paint.color = Color.WHITE
        job = GlobalScope.launch {
            var canvas: Canvas?
            cy = height-dy*2f
            while (true) {
                canvas = holder.lockCanvas(null)
                if (canvas != null) {
                    canvas.drawColor(Color.argb(255, 255, 255, 255))
                    paint.color = Color.GREEN
                    canvas.drawRect(0f, cy+dy, width.toFloat(), height.toFloat(), paint)

                    paint.color = Color.BLACK
                    canvas.drawCircle(2*r+cx, h+cy, r, paint)
                    canvas.drawCircle(9*r+cx, h+cy, r, paint)

                    paint.color = Color.WHITE
                    var dfx = ( r*cos(f* PI/180) ).toFloat()
                    var dfy = ( r*sin(f* PI/180) ).toFloat()
                    var dfx2 = ( r*cos((f+90)* PI/180) ).toFloat()
                    var dfy2 = ( r*sin((f+90)* PI/180) ).toFloat()
                    canvas.drawLine(2*r+cx-dfx, h+cy-dfy,2*r+cx+dfx, h+cy+dfy, paint)
                    canvas.drawLine(9*r+cx-dfx, h+cy-dfy,9*r+cx+dfx, h+cy+dfy, paint)
                    canvas.drawLine(2*r+cx-dfx2, h+cy-dfy2,2*r+cx+dfx2, h+cy+dfy2, paint)
                    canvas.drawLine(9*r+cx-dfx2, h+cy-dfy2,9*r+cx+dfx2, h+cy+dfy2, paint)
                    paint.color = Color.GRAY
                    canvas.drawRect(cx, cy, l2+cx, h+cy, paint)
                    paint.color = Color.WHITE
                    canvas.drawCircle(cx+r2+cx2, cy+r2+cy2, r2, paint)

                    holder.unlockCanvasAndPost(canvas)
                }
                cx+=dx
                f+=df
                cx2+=dx2
                cy2+=dy2
                if (cx+l2 > width || cx < 0) {
                    dx=-dx
                    df = -df
                }
                if (f>360) { f -= 360 }
                if (f<-360) { f += 360 }
                if (cx+r2+cx2+r2 > l2+cx || cx+r2+cx2-r2 < cx) {
                    dx2= -dx2
                }
                if (cy+r2+cy2+r2 > h+cy || cy+r2+cy2-r2 < cy) {
                    dy2 = -dy2
                }

            }
        }

    }

    override fun surfaceDestroyed(holder: SurfaceHolder) {
        job.cancel()
    }

    init {
        holder.addCallback(this)
    }
}