Android仿今日头条手界面

Posted 2020-10-01 新年新气象934060369

public class MyIndicator extends HorizontalScrollView implements ViewPager.OnPageChangeListener {
    private ViewPager mViewPager;
    private LinearLayout myLinearLayout;

    /**
     * 我们实现了ViewPager.OnPageChangeListener接口，因为我们要监听ViewPager的滑页行为，从而去改变导航栏的状态
     * 所以我们也可以看到，MyIndicator持有ViewPager的引用，如果我们还想要监听ViewPager怎么办呢？
     * 这里我为MyIndicator提供了一个接口，与OnPageChangeListener方法一样调用
     **/

    MyOnPageChangeListener mListener;

    private interface MyOnPageChangeListener {
        void onPageScrolled(int position, float positionOffset, int positionOffsetPixels);

        void onPageSelected(int position);

        void onPageScrollStateChanged(int state);
    }

    private int oldSelected;

    //为了让TextView能点击，我为每个TextView都设置了OnClickListener,
    //就是获得目标标题栏的index，然后调用setCurrentItem()就可以了,这样就实现了点击滑动的效果，点击标题栏，Viewpager也会跟着翻页。
    private final OnClickListener mTabClickListener = new OnClickListener() {
        public void onClick(View view) {
            MyTabView tabView = (MyTabView) view;
            oldSelected = mViewPager.getCurrentItem();
            final int newSelected = tabView.index;
            setCurrentItem(newSelected);
        }
    };

    public MyIndicator(Context context) {
        super(context);
        init(context);
    }

    public MyIndicator(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public MyIndicator(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context);
    }

    private void init(Context mcontext) {
        setHorizontalScrollBarEnabled(false);//隐藏自带的滚动条
        //添加linearLayout
        myLinearLayout = new LinearLayout(mcontext);
        myLinearLayout.setOrientation(LinearLayout.HORIZONTAL);

        addView(myLinearLayout, new ViewGroup.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT));
    }

    public void setViewPager(ViewPager viewPager) {
        setViewPager(viewPager, 0);
    }

    @SuppressWarnings("deprecation")
    public void setViewPager(ViewPager viewPager, int initPos) {
        if (mViewPager == viewPager) {
            return;
        }
        if (mViewPager != null) {
            mViewPager.setOnPageChangeListener(null);
        }
        final PagerAdapter adapter = viewPager.getAdapter();
        if (adapter == null) {
            throw new IllegalStateException("ViewPager does not have adapter instance.");
        }
        mViewPager = viewPager;
        viewPager.setOnPageChangeListener(this);
        notifyDataSetChanged();
        setCurrentItem(initPos);
    }

    private void notifyDataSetChanged() {
        myLinearLayout.removeAllViews();
        PagerAdapter mAdapter = mViewPager.getAdapter();
        int count = mAdapter.getCount();
        for (int i = 0; i < count; i++) {
            addTab(i, mAdapter.getPageTitle(i));
        }
        requestLayout();
    }

    /**
     * 代码添加顶部的TextView
     *
     * @param index
     * @param text
     */
    private void addTab(int index, CharSequence text) {
        MyTabView tabView = new MyTabView(getContext());
        tabView.index = index;
        tabView.setFocusable(true);
        tabView.setOnClickListener(mTabClickListener);
        tabView.setText(text);
        tabView.setTextSize(22);
        tabView.setTextColor(getContext().getResources().getColor(R.color.colorWhite));
        tabView.setPadding(20, 0, 20, 0);
        tabView.setTextAlignment(View.TEXT_ALIGNMENT_CENTER);
        PagerAdapter mAdapter = mViewPager.getAdapter();
        int screenWidth = getResources().getDisplayMetrics().widthPixels;
        if (mAdapter.getCount() <= 4) {
            tabView.setWidth(screenWidth / mAdapter.getCount());
        } else {
            tabView.setWidth(screenWidth / 4);
        }


        myLinearLayout.addView(tabView);
    }

    /**
     * 被选中的动画
     *
     * @param view
     */
    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    @SuppressLint("NewApi")
    private void animation(View view) {
        ObjectAnimator scaleX = ObjectAnimator.ofFloat(view, "scaleX", 1f);
        ObjectAnimator scaleY = ObjectAnimator.ofFloat(view, "scaleY", 1f);
        ObjectAnimator fade = ObjectAnimator.ofFloat(view, "alpha", 1f);
        AnimatorSet animSet = new AnimatorSet();
        animSet.play(scaleX).with(scaleY).with(fade);
        animSet.setDuration(500);
        animSet.start();
    }

    /**
     * 没选中的动画
     *
     * @param view
     */
    private void animation2(View view) {
        ObjectAnimator scaleX = ObjectAnimator.ofFloat(view, "scaleX", 0.8f);
        ObjectAnimator scaleY = ObjectAnimator.ofFloat(view, "scaleY", 0.8f);
        ObjectAnimator fade = ObjectAnimator.ofFloat(view, "alpha", 0.5f);
        AnimatorSet animSet = new AnimatorSet();
        animSet.play(scaleX).with(scaleY).with(fade);
        animSet.setDuration(500);
        animSet.start();
    }

    public void setCurrentItem(int item) {
        if (mViewPager == null) {
            throw new IllegalStateException("ViewPager has not been bound.");
        }
        int mSelectedTabIndex = item;
        mViewPager.setCurrentItem(item);

        final int tabCount = myLinearLayout.getChildCount();
        for (int i = 0; i < tabCount; i++) {//遍历标题，改变选中的背景
            final View child = myLinearLayout.getChildAt(i);
            final boolean isSelected = (i == item);
            child.setSelected(isSelected);
            if (isSelected) {
                animation(child);
                animateToTab(item);//动画效果
            } else {
                animation2(child);
                child.setBackgroundColor(Color.TRANSPARENT);
            }
        }
    }

    private Runnable mTabSelector;

    private void animateToTab(final int position) {
        final View tabView = myLinearLayout.getChildAt(position);
        if (mTabSelector != null) {
            removeCallbacks(mTabSelector);
        }
        mTabSelector = new Runnable() {
            public void run() {
                final int scrollPos = tabView.getLeft() - (getWidth() - tabView.getWidth()) / 2;//计算要滑动到的位置
                smoothScrollTo(scrollPos, 0);
                mTabSelector = null;
            }
        };
        post(mTabSelector);    //在主线程执行动画
    }

    public void setMyOnPageChangeListener(MyOnPageChangeListener listener) {
        mListener = listener;
    }

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        if (mListener != null)
            mListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
    }

    @Override
    public void onPageSelected(int position) {
        setCurrentItem(position);
        if (mListener != null) mListener.onPageSelected(position);
    }

    @Override
    public void onPageScrollStateChanged(int state) {
        if (mListener != null) mListener.onPageScrollStateChanged(state);
    }





}

 使用：

<com.cqytjr.www.cheji.views.MyIndicator
        android:id="@+id/indicator"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#c4c77f"/>



    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

 

 FragmentPagerAdapter adapter = new MyFragmentManager(getSupportFragmentManager(), content);

        pager = (ViewPager)findViewById(R.id.pager);
        indicator = (MyIndicator)findViewById(R.id.indicator);

        pager.setAdapter(adapter);
        indicator.setViewPager(pager);