Android – 自定义Loading圆点

网络等待Loading图

Loading.gif

刚开始做这种效果是用xml来画圆形实心点的。
白色圆点

    android:shape="oval" >
    
    

灰色圆点

    android:shape="oval" >
    
    

Loading布局文件

使用Timer来修改background

Timer  mTimer = new Timer();
        mHandler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                if(mPosition ==1) {
                    mIvDot1.setBackgroundResource(R.drawable.dot_focus);
                    mIvDot2.setBackgroundResource(R.drawable.dot_unfocus);
                    mIvDot3.setBackgroundResource(R.drawable.dot_unfocus);
                    mPosition = 2;
                } else if(mPosition == 2) {
                    mIvDot1.setBackgroundResource(R.drawable.dot_unfocus);
                    mIvDot2.setBackgroundResource(R.drawable.dot_focus);
                    mIvDot3.setBackgroundResource(R.drawable.dot_unfocus);
                    mPosition = 3;
                } else if(mPosition == 3) {
                    mIvDot1.setBackgroundResource(R.drawable.dot_unfocus);
                    mIvDot2.setBackgroundResource(R.drawable.dot_unfocus);
                    mIvDot3.setBackgroundResource(R.drawable.dot_focus);
                    mPosition = 1;
                }
            }
        };

        mTimer.schedule(new TimerTask() {
            @Override
            public void run() {
                mHandler.sendEmptyMessage(0);
            }
        }, 0, 400);

这样也是可以达到上面那种效果的，但是总感觉这么写不太符合程序员的风格。。。所以就有了下面的这种写法。

public class LoadingPointView extends View {
    public static final int MESSAGE_ID = 0;
    //白色圆点
    private Paint mWhitePaint;
    //绿色圆点
    private Paint mGreenPaint;
    //半径
    private int mRadius;
    //下一个被选中的圆点的index
    private int mIndex;
    private Handler mHandler = new Handler() {

        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            ++mIndex;
            if (mIndex == 5) {
                mIndex = 0;
            }
            postInvalidate();
        }
    };

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

    public LoadingPointView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public LoadingPointView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initParmas(context);
    }

    private void initParmas(Context context) {
        mWhitePaint = new Paint();
        mWhitePaint.setAntiAlias(true);
        mWhitePaint.setStyle(Paint.Style.FILL);
        mWhitePaint.setColor(ContextCompat.getColor(context, R.color.white));

        mGreenPaint = new Paint();
        mGreenPaint.setAntiAlias(true);
        mGreenPaint.setStyle(Paint.Style.FILL);
        mGreenPaint.setColor(ContextCompat.getColor(context, R.color.c_3ec88e));

        mPaintWidth = Px2DpUtil.dp2px(context, 2);
        mCircleX = Px2DpUtil.dp2px(context, 40);
        mCircleY = Px2DpUtil.dp2px(context, 40);
        mRadius = Px2DpUtil.dp2px(context, 5);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        for (int i = 0; i < 5; i++) {
            //修改圆心x轴坐标，来画出多个圆点
            canvas.drawCircle(getHeight() / 2 + mRadius * i * 2 + 5 * i, getHeight() / 2, mRadius, mWhitePaint);
        }
        //动态修改绿色圆点的位置
        canvas.drawCircle(getHeight() / 2 + mRadius * mIndex * 2 + 5 * mIndex, getHeight() / 2, mRadius, mGreenPaint);
        //发送消息不断绘制，以达到无限循环的效果
        mHandler.sendEmptyMessageDelayed(MESSAGE_ID, 200);
    }
    //停止动画
    @Override
    protected void onDetachedFromWindow() {
        super.onDetachedFromWindow();
        mHandler.removeMessages(MESSAGE_ID);
        mHandler = null;
    }
}

使用方法

具体效果和实现就是以上这些内容了。有什么问题可以评论。

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