閑來無事,擼了一個自定義view隨機(jī)數(shù),也算是學(xué)習(xí)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?) {
        //獲取控件中包含的屬性
        val typeArray = context.obtainStyledAttributes(attrs, R.styleable.text_view);
        //分別獲取設(shè)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();    //此方法即使回收獲取屬性,避免內(nèi)存泄漏
        mPain = Paint();
        mPain!!.textSize = textSize.toFloat();
        mBound = Rect();
        mPain!!.getTextBounds(textTest, 0, textTest.length, mBound);
        //設(shè)置控件點擊事件
        setOnClickListener {
            textTest = randomText();
            postInvalidate();   //重新繪制該方法調(diào)用后只會調(diào)用onDraw方法
        }
    }

    /**
     * 處理布局文件中設(shè)置wrap_content時view滿屏問題
     * 系統(tǒng)默認(rèn)測量寬高為match_parent
     * MeasureSpec分為三種模式:
     * EXACTLY設(shè)置確切的值或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,一般為源碼所用
     */
    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);    //設(shè)置最終測量寬高
    }

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

        mPain!!.color = Color.GREEN //繪制文字
        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();
    }
}