可拖拽的懸浮控件是個(gè)比較常見(jiàn)的很簡(jiǎn)單的效果眯亦，主要知識(shí)點(diǎn)：

1.View的簡(jiǎn)單自定義化戳，onDraw的重寫等

2.View事件的簡(jiǎn)單應(yīng)用

我們?cè)谶@個(gè)可拖拽的View上加個(gè)黃色的線搜吧，簡(jiǎn)單操作下這個(gè)View的樣子偎蘸，另外帚称，給這個(gè)拖拽View加上偏左吸左偏右吸右的效果嘹叫。下面直接上代碼：

public class CustomView extends android.support.v7.widget.AppCompatTextView {

    private Paint paint;//畫筆
    private int lastX;//記錄上一個(gè)X坐標(biāo)
    private int lastY;//記錄上一個(gè)Y坐標(biāo)


    public CustomView(Context context) {
        super(context);
        initDraw();
    }

    public CustomView(Context context, @Nullable  AttributeSet attrs) {
        super(context, attrs);
        initDraw();

    }

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


    @Override
    public boolean onTouchEvent(MotionEvent event) {

        int x = (int) event.getX();
        int y = (int) event.getY();

        int rawX = (int) event.getRawX();
        int rawY = (int) event.getRawY();

        int offsetX = x - lastX;
        int offsetY = y - lastY;

        ViewGroup mViewGroup = (ViewGroup) getParent();

        //取組件父集的寬高
        int pWidth = mViewGroup.getWidth();
        int pHeight = mViewGroup.getHeight();

        //設(shè)置上下左右的坐標(biāo)臨界值
        int left = getLeft() + offsetX;
        left = left <= 0 ? 0 : left;

        int top = getTop() + offsetY;
        top = top <= 0 ? 0 : top;

        int right = getRight() + offsetX;
        right = right >= pWidth ? pWidth : right;

        int bottom = getBottom() + offsetY;
        bottom = bottom >= pHeight ? pHeight : bottom;

        //設(shè)置上下左右的坐標(biāo)為臨界值時(shí)相關(guān)變量的值
        if(top==0){
            bottom =getHeight();
        }
        if(left==0){
            right=getWidth();
        }
        if(right==pWidth){
            left=pWidth-getWidth();
        }
        if(bottom==pHeight){
            top=pHeight-getHeight();
        }
        //判斷時(shí)間種類
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                lastX = x;
                lastY = y;
                break;
            case MotionEvent.ACTION_MOVE:
                layout(left, top, right, bottom);//移動(dòng)式更新布局
                break;
            case MotionEvent.ACTION_UP:
                //松開(kāi)手時(shí)根據(jù)組件中間的位置，判斷吸左吸右
                if (rawX <= pWidth / 2) {
                    layout(0, top, getWidth(), bottom);
                } else {
                    layout(pWidth - getWidth(), top, pWidth, bottom);
                }

                break;
        }

        return true;
    }

    /**
     * 初始化畫筆
     * */
    private void initDraw() {
        paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        paint.setColor(Color.YELLOW);
        paint.setStrokeWidth(1.5f);
    }

    @Override
    protected void onDraw(Canvas canvas) {

        super.onDraw(canvas);
        int width = getWidth();
        int height = getHeight();
        //畫布劃線
        canvas.drawLine(0, height / 2, width, height / 2, paint);
    }
}

ok丛肢，把這個(gè)組件直接在布局中展示就行了围肥，很簡(jiǎn)單。
demo git地址