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AppBar控件的使用方式

AppBar作为Android5.0的重要动画效果, 非常绚丽的UI, 通过内容驱动, 可以减少页面的访问, 更加便捷的传递主题思想. 那么我们看看如何使用.

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本文源码的GitHub 下载地址

AppBar控件的使用方式

配置

创建一个Navigation Drawer的工程, 修改主题颜色.

<resources>
    <color name="colorPrimary">#FF1493</color>
    <color name="colorPrimaryDark">#FF1493</color>
    <color name="colorAccent">#FF4081</color>
</resources>

修改抽屉的渐变颜色side_nav_bar.xml

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle" >
    <gradient
        android:startColor="#FF34"
        android:centerColor="#FF3E96"
        android:endColor="#FF1493"
        android:type="linear"
        android:angle="135"/>
</shape>

ViewPager

修改app_bar_main.xml, 在CoordinatorLayout中添加ViewPager.

<android.support.v4.view.ViewPager
    android:id="@+id/main_vp_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"/>

设置ViewPager的Fragment内容

/**
 * 简单的Fragment
 * <p/>
 * Created by wangchenlong on 15/11/9.
 */
public class SimpleFragment extends Fragment {
    private static final String ARG_SELECTION_NUM = "arg_selection_num";

    @Bind(R.id.main_tv_text) TextView mTvText;

    public SimpleFragment() {
    }

    public static SimpleFragment newInstance(int selectionNum) {
        SimpleFragment simpleFragment = new SimpleFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_SELECTION_NUM, selectionNum);
        simpleFragment.setArguments(args);
        return simpleFragment;
    }


    @Nullable @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_main, container, false);

        ButterKnife.bind(this, view);
        return view;
    }

    @Override public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        mTvText.setText("Page " + String.valueOf(getArguments().getInt(ARG_SELECTION_NUM)));
    }

    @Override public void onDestroyView() {
        super.onDestroyView();
        ButterKnife.unbind(this);
    }
}

设置ViewPager的适配器

/**
 * ViewPager的适配器
 * <p/>
 * Created by wangchenlong on 15/11/9.
 */
public class SimpleAdapter extends FragmentPagerAdapter {

    private static final String[] TITLE = {"SELECTION 1", "SELECTION 2", "SELECTION 3"};

    public SimpleAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override public Fragment getItem(int position) {
        return SimpleFragment.newInstance(position + 1);
    }

    @Override public int getCount() {
        return TITLE.length;
    }

    @Override public CharSequence getPageTitle(int position) {
        if (position >= 0 && position < TITLE.length) {
            return TITLE[position];
        }
        return null;
    }
}

在MainActivity中添加ViewPager逻辑

mVpContainer.setAdapter(new SimpleAdapter(getSupportFragmentManager()));

AppBarLayout

修改AppBarLayout, 添加CollapsingToolbarLayout.

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:fitsSystemWindows="true"
    android:theme="@style/AppTheme.AppBarOverlay">

    <android.support.design.widget.CollapsingToolbarLayout
        android:layout_width="match_parent"
        android:layout_height="400dp"
        android:fitsSystemWindows="true"
        app:contentScrim="?attr/colorPrimary"
        app:expandedTitleMarginStart="16dp"
        app:expandedTitleMarginEnd="16dp"
        app:layout_scrollFlags="scroll|exitUntilCollapsed">

        <ImageView
            android:id="@+id/toolbar_iv_image"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:adjustViewBounds="true"
            android:contentDescription="@null"
            android:fitsSystemWindows="true"
            android:scaleType="centerCrop"
            android:src="@drawable/taeyeon"
            app:layout_collapseMode="parallax"/>

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:layout_collapseMode="pin"
            app:popupTheme="@style/AppTheme.PopupOverlay"/>

    </android.support.design.widget.CollapsingToolbarLayout>

删除Toolbar的background颜色, 避免Toolbar挡住图片;

AppBarLayout设置 fitsSystemWindows 覆盖StatusBar背景;

CollapsingToolbarLayout包含图片和Toolbar.

TabLayout

在AppBarLayout中, 添加TabLayout

<android.support.design.widget.TabLayout
    android:id="@+id/toolbar_tl_tab"
    android:layout_width="match_parent"
    android:layout_height="?attr/actionBarSize"
    android:layout_gravity="bottom"
    app:layout_scrollFlags="scroll"/>

TabLayout添加 layout_scrollFlags 确保滑动.

把ViewPager加入TabLayout

mTlTab.setupWithViewPager(mVpContainer);

基本功能已经完成, 再添加随着页面切换AppBarLayout的图片视图.

渐变效果

在图片视图中, 再添加一层图片, 模拟渐变动画.

<FrameLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    app:layout_collapseMode="parallax">

    <ImageView
        android:id="@+id/toolbar_iv_outgoing"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:adjustViewBounds="true"
        android:contentDescription="@null"
        android:scaleType="centerCrop"
        android:visibility="gone"/>

    <ImageView
        android:id="@+id/toolbar_iv_image"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:adjustViewBounds="true"
        android:contentDescription="@null"
        android:fitsSystemWindows="true"
        android:scaleType="centerCrop"
        android:src="@drawable/tiffany"
        app:layout_collapseMode="parallax"/>
</FrameLayout>

修改Adapter, 为每个页面添加一个图片

/**
 * ViewPager的适配器
 * <p/>
 * Created by wangchenlong on 15/11/9.
 */
public class SimpleAdapter extends FragmentPagerAdapter {

    private static final Section[] SECTIONS = {
            new Section("Tiffany", R.drawable.tiffany),
            new Section("Taeyeon", R.drawable.taeyeon),
            new Section("Yoona", R.drawable.yoona)
    };

    public SimpleAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override public Fragment getItem(int position) {
        return SimpleFragment.newInstance(position + 1);
    }

    @Override public int getCount() {
        return SECTIONS.length;
    }

    @Override public CharSequence getPageTitle(int position) {
        if (position >= 0 && position < SECTIONS.length) {
            return SECTIONS[position].getTitle();
        }
        return null;
    }

    @DrawableRes
    public int getDrawable(int position) {
        if (position >= 0 && position < SECTIONS.length) {
            return SECTIONS[position].getDrawable();
        }
        return -1;
    }

    private static final class Section {
        private final String mTitle; // 标题
        @DrawableRes private final int mDrawable; // 图片

        public Section(String title, int drawable) {
            mTitle = title;
            mDrawable = drawable;
        }

        public String getTitle() {
            return mTitle;
        }

        public int getDrawable() {
            return mDrawable;
        }
    }
}

两个图像页面的渐变动画

/**
 * 渐变的动画效果
 * <p/>
 * Created by wangchenlong on 15/11/9.
 */
public class ImageAnimator {

    private final SimpleAdapter mAdapter; // 适配器
    private final ImageView mTargetImage; // 原始图片
    private final ImageView mOutgoingImage; // 渐变图片

    private int mActualStart; // 实际起始位置

    public ImageAnimator(SimpleAdapter adapter, ImageView targetImage, ImageView outgoingImage) {
        mAdapter = adapter;
        mTargetImage = targetImage;
        mOutgoingImage = outgoingImage;
    }

    /**
     * 启动动画, 之后选择向前或向后滑动
     *
     * @param startPosition 起始位置
     * @param endPosition   终止位置
     */
    public void start(int startPosition, int endPosition) {
        mActualStart = startPosition;

        // 终止位置的图片
        @DrawableRes int incomeId = mAdapter.getDrawable(endPosition);

        // 原始图片
        mOutgoingImage.setImageDrawable(mTargetImage.getDrawable()); // 原始的图片
        mOutgoingImage.setVisibility(View.VISIBLE);
        mOutgoingImage.setAlpha(1.0f);

        // 目标图片
        mTargetImage.setImageResource(incomeId);
    }

    /**
     * 滑动结束的动画效果
     *
     * @param endPosition 滑动位置
     */
    public void end(int endPosition) {
        @DrawableRes int incomeId = mAdapter.getDrawable(endPosition);
        mTargetImage.setTranslationX(0f);

        // 设置原始图片
        if (endPosition == mActualStart) {
            mTargetImage.setImageDrawable(mOutgoingImage.getDrawable());
        } else {
            mTargetImage.setImageResource(incomeId);
            mTargetImage.setAlpha(1f);
            mOutgoingImage.setVisibility(View.GONE);
        }
    }

    // 向后滚动, 比如0->1, offset滚动的距离(0->1), 目标渐渐淡出
    public void forward(float positionOffset) {
        mTargetImage.setAlpha(positionOffset);
    }

    // 向前滚动, 比如1->0, offset滚动的距离(1->0), 目标渐渐淡出
    public void backwards(float positionOffset) {
        mTargetImage.setAlpha(1 - positionOffset);
    }
}

注释已经写的很详细了, 注意的是向前向后滑动, position的值不同. 向前滑动, position的值是当前值减一; 向后滑动, position的值不变. 也就是说, position总是较小值. 偏移量, 向后滑动时, 从0至1; 向前滑动时, 从1至0.

ViewPager的监听, 使用动画效果

/**
 * ViewPager滑动页面监听
 * <p/>
 * Created by wangchenlong on 15/11/9.
 */
public class PagerChangeListener implements ViewPager.OnPageChangeListener {
    private ImageAnimator mImageAnimator;

    private int mCurrentPosition;

    private int mFinalPosition;

    private boolean mIsScrolling = false;

    public PagerChangeListener(ImageAnimator imageAnimator) {
        mImageAnimator = imageAnimator;
    }

    public static PagerChangeListener newInstance(SimpleAdapter adapter, ImageView originImage, ImageView outgoingImage) {
        ImageAnimator imageAnimator = new ImageAnimator(adapter, originImage, outgoingImage);
        return new PagerChangeListener(imageAnimator);
    }

    /**
     * 滑动监听
     *
     * @param position             当前位置
     * @param positionOffset       偏移[当前值+-1]
     * @param positionOffsetPixels 偏移像素
     */
    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

        Log.e("DEBUG-WCL", "position: " + position + ", positionOffset: " + positionOffset);

        // 以前滑动, 现在终止
        if (isFinishedScrolling(position, positionOffset)) {
            finishScroll(position);
        }

        // 判断前后滑动
        if (isStartingScrollToPrevious(position, positionOffset)) {
            startScroll(position);
        } else if (isStartingScrollToNext(position, positionOffset)) {
            startScroll(position + 1); // 向后滚动需要加1
        }

        // 向后滚动
        if (isScrollingToNext(position, positionOffset)) {
            mImageAnimator.forward(positionOffset);
        } else if (isScrollingToPrevious(position, positionOffset)) { // 向前滚动
            mImageAnimator.backwards(positionOffset);
        }
    }

    /**
     * 终止滑动
     * 滑动 && [偏移是0&&滑动终点] || 动画之中
     *
     * @param position       位置
     * @param positionOffset 偏移量
     * @return 终止滑动
     */
    public boolean isFinishedScrolling(int position, float positionOffset) {
        return mIsScrolling && (positionOffset == 0f && position == mFinalPosition);
    }

    /**
     * 从静止到开始滑动, 下一个
     * 未滑动 && 位置是当前位置 && 偏移量不是0
     *
     * @param position       位置
     * @param positionOffset 偏移量
     * @return 是否
     */
    private boolean isStartingScrollToNext(int position, float positionOffset) {
        return !mIsScrolling && position == mCurrentPosition && positionOffset != 0f;
    }

    /**
     * 从静止到开始滑动, 前一个[position会-1]
     *
     * @param position       位置
     * @param positionOffset 偏移量
     * @return 是否
     */
    private boolean isStartingScrollToPrevious(int position, float positionOffset) {
        return !mIsScrolling && position != mCurrentPosition && positionOffset != 0f;
    }

    /**
     * 开始滚动, 向后
     *
     * @param position       位置
     * @param positionOffset 偏移
     * @return 是否
     */
    private boolean isScrollingToNext(int position, float positionOffset) {
        return mIsScrolling && position == mCurrentPosition && positionOffset != 0f;
    }

    /**
     * 开始滚动, 向前
     *
     * @param position       位置
     * @param positionOffset 偏移
     * @return 是否
     */
    private boolean isScrollingToPrevious(int position, float positionOffset) {
        return mIsScrolling && position != mCurrentPosition && positionOffset != 0f;
    }

    /**
     * 开始滑动
     * 滚动开始, 结束位置是position[前滚时position会自动减一], 动画从当前位置到结束位置.
     *
     * @param position 滚动结束之后的位置
     */
    private void startScroll(int position) {
        mIsScrolling = true;
        mFinalPosition = position;

        // 开始滚动动画
        mImageAnimator.start(mCurrentPosition, position);
    }

    /**
     * 如果正在滚动, 结束时, 固定position位置, 停止滚动, 调动截止动画
     *
     * @param position 位置
     */
    private void finishScroll(int position) {
        if (mIsScrolling) {
            mCurrentPosition = position;
            mIsScrolling = false;
            mImageAnimator.end(position);
        }
    }

    @Override
    public void onPageScrollStateChanged(int state) {
        //NO-OP
    }

    @Override
    public void onPageSelected(int position) {
        if (!mIsScrolling) {
            mIsScrolling = true;
            mFinalPosition = position;
            mImageAnimator.start(mCurrentPosition, position);
        }
    }
}

详细内容参见注释

ViewPager添加滚动监听.

SimpleAdapter adapter = new SimpleAdapter(getSupportFragmentManager());
mVpContainer.setAdapter(adapter);
mVpContainer.addOnPageChangeListener(PagerChangeListener.newInstance(adapter, mIvTarget, mIvOutgoing));

页面滚动

在ViewPager上, 嵌套NestedScrollView.

<android.support.v4.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fillViewport="true"
    android:scrollbars="none"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <android.support.v4.view.ViewPager
        android:id="@+id/main_vp_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"/>

</android.support.v4.widget.NestedScrollView>

android:fillViewport 允许ScrollView内的组件填充, 否则ViewPager显示.

设置标题, MainActivity.

setTitle("Girls' Generation");

动画效果

偏移滚动

额, 与其说是AppBar, 不如说是ViewPager, 再添加一些动画效果, 和修复Bug.

把图片的左右10%, 隐藏起来, 滑动时, 一边渐变一边侧移.

在 app_bar_main 中, 替换 FrameLayout 为 PercentFrameLayout , 宽度设置为 120% .

<android.support.percent.PercentFrameLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:fitsSystemWindows="true"
    app:layout_collapseMode="parallax">

    <ImageView
        android:id="@+id/toolbar_iv_outgoing"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:adjustViewBounds="true"
        android:contentDescription="@null"
        android:scaleType="centerCrop"
        android:visibility="gone"
        app:layout_widthPercent="120%"/>

    <ImageView
        android:id="@+id/toolbar_iv_target"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:adjustViewBounds="true"
        android:contentDescription="@null"
        android:fitsSystemWindows="true"
        android:scaleType="centerCrop"
        android:src="@drawable/tiffany"
        app:layout_collapseMode="parallax"
        app:layout_widthPercent="120%"/>

</android.support.percent.PercentFrameLayout>

修改滑动动画(Image), 在向前向后滑动时, setTranslationX X轴平移.

/**
 * 渐变的动画效果
 * <p/>
 * Created by wangchenlong on 15/11/9.
 */
public class ImageAnimator {

    private static final float FACTOR = 0.1f;

    private final SimpleAdapter mAdapter; // 适配器
    private final ImageView mTargetImage; // 原始图片
    private final ImageView mOutgoingImage; // 渐变图片

    private int mActualStart; // 实际起始位置

    private int mStart;
    private int mEnd;

    public ImageAnimator(SimpleAdapter adapter, ImageView targetImage, ImageView outgoingImage) {
        mAdapter = adapter;
        mTargetImage = targetImage;
        mOutgoingImage = outgoingImage;
    }

    /**
     * 启动动画, 之后选择向前或向后滑动
     *
     * @param startPosition 起始位置
     * @param endPosition   终止位置
     */
    public void start(int startPosition, int endPosition) {
        mActualStart = startPosition;

        // 终止位置的图片
        @DrawableRes int incomeId = mAdapter.getDrawable(endPosition);

        // 原始图片
        mOutgoingImage.setImageDrawable(mTargetImage.getDrawable()); // 原始的图片

        // 起始图片
        mOutgoingImage.setTranslationX(0f);

        mOutgoingImage.setVisibility(View.VISIBLE);
        mOutgoingImage.setAlpha(1.0f);

        // 目标图片
        mTargetImage.setImageResource(incomeId);

        mStart = Math.min(startPosition, endPosition);
        mEnd = Math.max(startPosition, endPosition);
    }

    /**
     * 滑动结束的动画效果
     *
     * @param endPosition 滑动位置
     */
    public void end(int endPosition) {
        @DrawableRes int incomeId = mAdapter.getDrawable(endPosition);
        mTargetImage.setTranslationX(0f);

        // 设置原始图片
        if (endPosition == mActualStart) {
            mTargetImage.setImageDrawable(mOutgoingImage.getDrawable());
        } else {
            mTargetImage.setImageResource(incomeId);
            mTargetImage.setAlpha(1f);
            mOutgoingImage.setVisibility(View.GONE);
        }
    }

    // 向前滚动, 比如0->1, offset滚动的距离(0->1), 目标渐渐淡出
    public void forward(float positionOffset) {
        Log.e("DEBUG-WCL", "forward-positionOffset: " + positionOffset);
        int width = mTargetImage.getWidth();
        mOutgoingImage.setTranslationX(-positionOffset * (FACTOR * width));
        mTargetImage.setTranslationX((1 - positionOffset) * (FACTOR * width));

        mTargetImage.setAlpha(positionOffset);
    }

    // 向后滚动, 比如1->0, offset滚动的距离(1->0), 目标渐渐淡入
    public void backwards(float positionOffset) {
        Log.e("DEBUG-WCL", "backwards-positionOffset: " + positionOffset);
        int width = mTargetImage.getWidth();
        mOutgoingImage.setTranslationX((1 - positionOffset) * (FACTOR * width));
        mTargetImage.setTranslationX(-(positionOffset) * (FACTOR * width));

        mTargetImage.setAlpha(1 - positionOffset);
    }

    // 判断停止
    public boolean isWithin(int position) {
        return position >= mStart && position < mEnd;
    }
}

修复滚动Bug, 连续滚动时, 及时更新当前图片, 否则图片异常.

/**
 * 终止滑动
 * 滑动 && [偏移是0&&滑动终点] || 动画之中 || 未在区间即连续滚动
 *
 * @param position       位置
 * @param positionOffset 偏移量
 * @return 终止滑动
 */
public boolean isFinishedScrolling(int position, float positionOffset) {
    return mIsScrolling && (positionOffset == 0f && position == mFinalPosition) || !mImageAnimator.isWithin(position);
}