Android实现启动页倒计时效果

@SuppressLint("AppCompatCustomView")
public class CountDownTextView extends TextView {
    // 倒计时动画时间
    private int duration = 5000;
    // 动画扫过的角度
    private int mSweepAngle = 360;
    // 属性动画
    private ValueAnimator animator;
    // 矩形用来保存位置大小信息
    private final RectF mRect = new RectF();
    // 圆弧的画笔
    private Paint mBackgroundPaint;

    public CountDownTextView(Context context) {
        this(context, null);
    }

    public CountDownTextView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public CountDownTextView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

  private void init() {
        // 设置画笔平滑
        mBackgroundPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        // 设置画笔颜色
        mBackgroundPaint.setColor(Color.WHITE);
        // 设置画笔边框宽度
        mBackgroundPaint.setStrokeWidth(5);
        // 设置画笔样式为边框类型
        mBackgroundPaint.setStyle(Paint.Style.STROKE);
    }
}

    
    public void start() {
        // 在动画中
        if (mSweepAngle != 360) return;
        //  初始化属性动画
        animator = ValueAnimator.ofInt(mSweepAngle).setDuration(duration);
        // 设置插值
        animator.setInterpolator(new LinearInterpolator());
        // 设置动画监听
        animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                // 获取属性动画返回的动画值
                mSweepAngle = (int) animation.getAnimatedValue();
                // 重绘自己
                invalidate();
            }
        });

        // 开始动画
        animator.start();
    }

 @Override
    protected void onDraw(canvas canvas) {
        int padding = dp2px(4);
        mRect.top = padding;
        mRect.left = padding;
        mRect.right = getWidth() - padding;
        mRect.bottom = getHeight() - padding;

        // 画倒计时线内圆
        canvas.drawArc(mRect, //弧线所使用的矩形区域大小
                -90,  //开始角度
                mSweepAngle, //扫过的角度
                false, //是否使用中心
                mBackgroundPaint); // 设置画笔

        super.onDraw(canvas);
    }

 <com.example.viewdemo.CountDownTextView
        android:id="@+id/tv_skip"
        style="@style/Widget.AppCompat.Button.Borderless"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:layout_gravity="center"
        android:background="@drawable/bg_count_down"
        android:text="跳过"
        android:textColor="#ffffff"
        android:textSize="12sp"
        android:visibility="visible" />

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="Http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true">
        <shape android:shape="oval">
            <solid android:color="#302d2d2d" />
        </shape>
    </item>
    <item>
        <shape android:shape="oval">
            <solid android:color="#7F2d2d2d" />
        </shape>
    </item>
</selector>

@SuppressLint("AppCompatCustomView")
public class CountDownTextView extends TextView {
    // 倒计时动画时间
    private int duration = 5000;
    // 动画扫过的角度
    private int mSweepAngle = 360;
    // 属性动画
    private ValueAnimator animator;
    // 矩形用来保存位置大小信息
    private final RectF mRect = new RectF();
    // 圆弧的画笔
    private Paint mBackgroundPaint;

    public CountDownTextView(Context context) {
        this(context, null);
    }

    public CountDownTextView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public CountDownTextView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

        init();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        int padding = 5;
        mRect.top = padding;
        mRect.left = padding;
        mRect.right = getWidth() - padding;
        mRect.bottom = getHeight() - padding;

        // 画倒计时线内圆
        canvas.drawArc(mRect, //弧线所使用的矩形区域大小
                -90,  //开始角度
                mSweepAngle, //扫过的角度
                false, //是否使用中心
                mBackgroundPaint); // 设置画笔

        start();

        super.onDraw(canvas);
    }

    private void init() {
        // 设置画笔平滑
        mBackgroundPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        // 设置画笔颜色
        mBackgroundPaint.setColor(Color.WHITE);
        // 设置画笔边框宽度
        mBackgroundPaint.setStrokeWidth(5);
        // 设置画笔样式为边框类型
        mBackgroundPaint.setStyle(Paint.Style.STROKE);
    }
    
    public void start() {
        // 在动画中
        if (mSweepAngle != 360) return;
        //  初始化属性动画
        animator = ValueAnimator.ofInt(mSweepAngle).setDuration(duration);
        // 设置插值
        animator.setInterpolator(new LinearInterpolator());
        // 设置动画监听
        animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                // 获取属性动画返回的动画值
                mSweepAngle = (int) animation.getAnimatedValue();
                // 重绘自己
                invalidate();
            }
        });

        // 开始动画
        animator.start();
    }
}