闲来无事,撸了一个自定义view随机数,也算是学习啦

class TestView : View {
    constructor(context: Context) : super(context) {
        init(context, null);
    }

    constructor(context: Context, attrs: AttributeSet?) : super(context, attrs) {
        init(context, attrs);
    }

    constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr) {
        init(context, attrs);
    }

    private var textSize: Int = 0;
    private var textTest: String = "";
    private var textColor: Int = 0;
    private var mPain: Paint? = null;
    private var mBound: Rect? = null;
    private fun init(context: Context, attrs: AttributeSet?) {
        //获取控件中包含的属性
        val typeArray = context.obtainStyledAttributes(attrs, R.styleable.text_view);
        //分别获取设置的值
        val indexCount = typeArray.indexCount
        (0..indexCount).map { typeArray.getIndex(it) }.forEach {
            when (it) {
                R.styleable.text_view_titleTextSize -> {
                    textSize = typeArray.getDimensionPixelSize(it, 16)
                }
                R.styleable.text_view_titleText -> {
                    textTest = typeArray.getString(it);
                }
                R.styleable.text_view_titleColor -> {
                    textColor = typeArray.getColor(it, Color.BLACK);
                }
            }
        }
        typeArray.recycle();    //此方法即使回收获取属性,避免内存泄漏
        mPain = Paint();
        mPain!!.textSize = textSize.toFloat();
        mBound = Rect();
        mPain!!.getTextBounds(textTest, 0, textTest.length, mBound);
        //设置控件点击事件
        setOnClickListener {
            textTest = randomText();
            postInvalidate();   //重新绘制该方法调用后只会调用onDraw方法
        }
    }

    /**
     * 处理布局文件中设置wrap_content时view满屏问题
     * 系统默认测量宽高为match_parent
     * MeasureSpec分为三种模式:
     * EXACTLY设置确切的值或Match_parent
     * AT_MOST布局限制在最大的值wrap_content
     * UNSPECIFIED 布局想要多大可以多大,一般为源码所用
     */
    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec)
        var width: Int;
        var height: Int;
        val widthMode = MeasureSpec.getMode(widthMeasureSpec);
        val widthSize = MeasureSpec.getSize(widthMeasureSpec);
        val heightMode = MeasureSpec.getMode(heightMeasureSpec);
        val heightSize = MeasureSpec.getSize(heightMeasureSpec);
        if (widthMode == MeasureSpec.EXACTLY) {
            width = widthSize;
        } else {
            mPain!!.textSize = textSize.toFloat();
            mPain!!.getTextBounds(textTest, 0, textTest.length, mBound);
            val textWidth = mBound!!.width();
            width = paddingLeft + textWidth + paddingRight;
        }
        if (heightMode == MeasureSpec.EXACTLY) {
            height = heightSize;
        } else {
            mPain!!.textSize = textSize.toFloat();
            mPain!!.getTextBounds(textTest, 0, textTest.length, mBound);
            val textHeight = mBound!!.height();
            height = paddingBottom + paddingTop + textHeight;
        }
        setMeasuredDimension(width, height);    //设置最终测量宽高
    }

    /**
     * 绘制界面方法
     * 尽量不要在view中做耗时操作
     */
    override fun onDraw(canvas: Canvas) {
        super.onDraw(canvas)
        mPain!!.color = Color.YELLOW    //绘制背景
        canvas.drawRect(0f, 0f, measuredWidth.toFloat(), measuredHeight.toFloat(), mPain);

        mPain!!.color = Color.GREEN //绘制文字
        canvas.drawText(textTest, (width / 2 - mBound!!.width() / 2).toFloat(), (height / 2 + mBound!!.height()/2).toFloat(), mPain)
    }

    private fun randomText(): String {
        val random = Random();
        var set = HashSet<Int>();
        while (set.size < 4){
            val randomInt = random.nextInt(10);
            set.add(randomInt)
        }
       val sb= StringBuffer();
        for (item in set){
            sb.append(""+item)
        }
        return sb.toString();
    }
}