【Kotlin】Kotlin 自定义组件 ( 自定义 View | 自定义 SurfaceView )

package kim.hsl.aa.view
import android.content.Context
import android.graphics.Canvas
import android.os.Build
import android.util.AttributeSet
import android.view.View
import androidx.annotation.RequiresApi
class MyView : View {
    val TAG: String = "MyView"
    constructor(context: Context?) : this(context, null, 0)
    constructor(context: Context?, attrs: AttributeSet?) : this(context, attrs, 0)
    constructor(context: Context?, attrs: AttributeSet?, defStyleAttr: Int) : 
      super(context, attrs, defStyleAttr)
    @RequiresApi(Build.VERSION_CODES.LOLLIPOP)
    constructor(context: Context?, attrs: AttributeSet?, defStyleAttr: Int, defStyleRes: Int) : 
      super(context, attrs, defStyleAttr, defStyleRes)
    override fun onDraw(canvas: Canvas?) {
        super.onDraw(canvas)
        // 绘制核心方法
    }
}

package kim.hsl.aa.view
import android.content.Context
import android.graphics.*
import android.os.Build
import android.util.AttributeSet
import android.view.SurfaceHolder
import android.view.SurfaceView
import androidx.annotation.RequiresApi
import kim.hsl.aa.R
class MySurfaceView : SurfaceView, SurfaceHolder.Callback, Runnable {
    val TAG = "MySurfaceView"
    /**
     * 渲染绘制标志
     */
    private var mDrawingFlag = false
    /**
     * 渲染线程
     */
    private var mRender: Thread? = null
    /**
     * 画布
     */
    private var mCanvas: Canvas? = null
    constructor(context: Context) : this(context, null, 0)
    constructor(context: Context, attrs : AttributeSet?) : this(context, attrs, 0)
    constructor(context: Context, attrs: AttributeSet?, defStyleAttr : Int) :
            super(context, attrs, defStyleAttr) {
        holder.addCallback(this)
        setZOrderOnTop(true)
        holder.setFormat(PixelFormat.TRANSLUCENT)
    }
    @RequiresApi(Build.VERSION_CODES.LOLLIPOP)
    constructor(context: Context, attrs: AttributeSet, defStyleAttr : Int, defStyleRes: Int) :
            super(context, attrs, defStyleAttr, defStyleRes)
    override fun run() {
        val paint = Paint()
        while (mDrawingFlag) {
            paint.setColor(Color.WHITE)
            mCanvas = holder.lockCanvas()
            if (mCanvas == null) continue
            mCanvas?.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR)
            //TODO 绘制逻辑
            holder.unlockCanvasAndPost(mCanvas)
            Thread.sleep(20)
        }
    }
    /*
        下面的三个函数是 实现 SurfaceHolder.Callback 接口方法
     */
    override fun surfaceChanged(holder: SurfaceHolder?, format: Int, width: Int, height: Int) {
        mDrawingFlag = true
        mRender = Thread(this)
        mRender?.start()
        // 加载图片
        var bitmap = BitmapFactory.decodeResource(resources, R.mipmap.ic_launcher)
    }
    override fun surfaceDestroyed(holder: SurfaceHolder?) {
    }
    override fun surfaceCreated(holder: SurfaceHolder?) {
    }
}