Android仿微信图片详情页面，可下拉关闭页面

话不多说，直接上效果图

imagereview.gif

1、要实现效果图的方案，需要操作重写ViewPager的事件处理。
2、下滑透明的方案可以使用设置背景来实现

下拉缩放的效果需要重写onInterceptTouchEvent和onTouchEvent,
在onInterceptTouchEvent中不拦截down事件，并且在move事件中判断是否满足下滑缩放的条件;
在onTouchEvent中实现具体的缩放以及透明度变化的效果;
同时在ViewPager的滑动要与下滑缩放区分开，因此需要监听OnPageChangeListener，并在onTouchEvent判断是否ViewPager在滑动中

public class DragViewPager extends ViewPager implements View.OnClickListener {
    public static final int STATUS_NORMAL = 0;//正常浏览状态
    public static final int STATUS_MOVING = 1;//滑动状态
    public static final int STATUS_RESETTING = 2;//返回中状态
    public static final String TAG = "DragViewPager";


    public static final float MIN_SCALE_SIZE = 0.3f;//最小缩放比例
    public static final int BACK_DURATION = 300;//ms
    public static final int DRAG_GAP_PX = 50;

    private int currentStatus = STATUS_NORMAL;
    private int currentPageStatus;

    private float mDownX;
    private float mDownY;
    private float screenHeight;

    /**
     * 要缩放的View
     */
    private View currentShowView;
    /**
     * 滑动速度检测类
     */
    private VelocityTracker mVelocityTracker;
    private IAnimClose iAnimClose;

    public void setIAnimClose(IAnimClose iAnimClose) {
        this.iAnimClose = iAnimClose;
    }

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

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

    public void init(Context context) {
        screenHeight = ScreenUtils.getScreenHeight(context);
        setBackgroundColor(Color.BLACK);
        addOnPageChangeListener(new OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
            }

            @Override
            public void onPageSelected(int position) {

            }

            @Override
            public void onPageScrollStateChanged(int state) {
                currentPageStatus = state;
            }
        });
    }


    public void setCurrentShowView(View currentShowView) {
        this.currentShowView = currentShowView;
        if (this.currentShowView != null) {
            this.currentShowView.setOnClickListener(this);
        }
    }



    //配合SubsamplingScaleImageView使用，根据需要拦截ACTION_MOVE
    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        if (getAdapter() instanceof ImagePagerAdapter) {
            ImagePagerAdapter adapter = ((ImagePagerAdapter) getAdapter());
            SubsamplingScaleImageView mImage = (SubsamplingScaleImageView) adapter.getItem(getCurrentItem()).getView().findViewById(R.id.image);
            switch (ev.getAction()){
                case MotionEvent.ACTION_DOWN:
                    Log.e("jc","onInterceptTouchEvent:ACTION_DOWN");
                    mDownX = ev.getRawX();
                    mDownY = ev.getRawY();
                    break;
                case MotionEvent.ACTION_MOVE:
                    Log.e("jc","onInterceptTouchEvent:ACTION_MOVE");
                    if (mImage.getCenter() != null && mImage.getCenter().y <= mImage.getHeight() / mImage.getScale() / 2) {
                        Log.e("jc","onInterceptTouchEvent:ACTION_MOVE");
                        int deltaX = Math.abs((int) (ev.getRawX() - mDownX));
                        int deltaY = (int) (ev.getRawY() - mDownY);
                        if (deltaY > DRAG_GAP_PX && deltaX <= DRAG_GAP_PX) {//往下移动超过临界，左右移动不超过临界时，拦截滑动事件
                            return true;
                        }
                    }
                    break;
                case MotionEvent.ACTION_UP:
                    Log.e("jc","onInterceptTouchEvent:ACTION_UP");
                    break;
            }
        }
        return super.onInterceptTouchEvent(ev);
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        if (currentStatus == STATUS_RESETTING)
            return false;
        switch (ev.getActionMasked()) {
            case MotionEvent.ACTION_DOWN:
                mDownX = ev.getRawX();
                mDownY = ev.getRawY();
                addIntoVelocity(ev);
                break;
            case MotionEvent.ACTION_MOVE:
                addIntoVelocity(ev);
                int deltaY = (int) (ev.getRawY() - mDownY);
                //手指往上滑动
                if (deltaY <= DRAG_GAP_PX && currentStatus != STATUS_MOVING)
                    return super.onTouchEvent(ev);
                //viewpager不在切换中，并且手指往下滑动，开始缩放
                if (currentPageStatus != SCROLL_STATE_DRAGGING && (deltaY > DRAG_GAP_PX || currentStatus == STATUS_MOVING)) {
                    moveView(ev.getRawX(), ev.getRawY());
                    return true;
                }
                break;
            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_CANCEL:
                if (currentStatus != STATUS_MOVING)
                    return super.onTouchEvent(ev);
                final float mUpX = ev.getRawX();
                final float mUpY = ev.getRawY();

                float vY = computeYVelocity();//松开时必须释放VelocityTracker资源
                if (vY >= 1200 || Math.abs(mUpY - mDownY) > screenHeight / 4) {
                    //下滑速度快，或者下滑距离超过屏幕高度的一半，就关闭
                    if (iAnimClose != null) {
                        iAnimClose.onPictureRelease(currentShowView);
                    }
                } else {
                    resetReviewState(mUpX, mUpY);
                }
                break;
        }

        return super.onTouchEvent(ev);
    }

    //返回浏览状态
    private void resetReviewState(final float mUpX, final float mUpY) {
        currentStatus = STATUS_RESETTING;
        if (mUpY != mDownY) {
            ValueAnimator valueAnimator = ValueAnimator.ofFloat(mUpY, mDownY);
            valueAnimator.setDuration(BACK_DURATION);
            valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    float mY = (float) animation.getAnimatedValue();
                    float percent = (mY - mDownY) / (mUpY - mDownY);
                    float mX = percent * (mUpX - mDownX) + mDownX;
                    moveView(mX, mY);
                    if (mY == mDownY) {
                        mDownY = 0;
                        mDownX = 0;
                        currentStatus = STATUS_NORMAL;
                    }
                }
            });
            valueAnimator.start();
        } else if (mUpX != mDownX) {
            ValueAnimator valueAnimator = ValueAnimator.ofFloat(mUpX, mDownX);
            valueAnimator.setDuration(BACK_DURATION);
            valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    float mX = (float) animation.getAnimatedValue();
                    float percent = (mX - mDownX) / (mUpX - mDownX);
                    float mY = percent * (mUpY - mDownY) + mDownY;
                    moveView(mX, mY);
                    if (mX == mDownX) {
                        mDownY = 0;
                        mDownX = 0;
                        currentStatus = STATUS_NORMAL;
                    }
                }
            });
            valueAnimator.start();
        } else if (iAnimClose != null)
            iAnimClose.onPictureClick();
    }


    //移动View
    private void moveView(float movingX, float movingY) {
        if (currentShowView == null)
            return;
        currentStatus = STATUS_MOVING;
        float deltaX = movingX - mDownX;
        float deltaY = movingY - mDownY;
        float scale = 1f;
        float alphaPercent = 1f;
        if (deltaY > 0) {
            scale = 1 - Math.abs(deltaY) / screenHeight;
            alphaPercent = 1 - Math.abs(deltaY) / (screenHeight / 2);
        }

        ViewHelper.setTranslationX(currentShowView, deltaX);
        ViewHelper.setTranslationY(currentShowView, deltaY);
        scaleView(scale);
        setBackgroundColor(getBlackAlpha(alphaPercent));
    }

    //缩放View
    private void scaleView(float scale) {
        scale = Math.min(Math.max(scale, MIN_SCALE_SIZE), 1);
        ViewHelper.setScaleX(currentShowView, scale);
        ViewHelper.setScaleY(currentShowView, scale);
    }


    private int getBlackAlpha(float percent) {
        percent = Math.min(1, Math.max(0, percent));
        int intAlpha = (int) (percent * 255);
        return Color.argb(intAlpha,0,0,0);
    }

    private void addIntoVelocity(MotionEvent event) {
        if (mVelocityTracker == null)
            mVelocityTracker = VelocityTracker.obtain();
        mVelocityTracker.addMovement(event);
    }


    private float computeYVelocity() {
        float result = 0;
        if (mVelocityTracker != null) {
            mVelocityTracker.computeCurrentVelocity(1000);
            result = mVelocityTracker.getYVelocity();
            releaseVelocity();
        }
        return result;
    }

    private void releaseVelocity() {
        if (mVelocityTracker != null) {
            mVelocityTracker.clear();
            mVelocityTracker.recycle();
            mVelocityTracker = null;
        }
    }

    @Override
    public void onClick(View v) {
        if (iAnimClose != null) {
            iAnimClose.onPictureClick();
        }
    }


    public interface IAnimClose {
        void onPictureClick();

        void onPictureRelease(View view);
    }


}

需要进行缩放的View我这里在Adapter中添加回调设置，并且adapter可以实现更新的效果

public class ImagePagerAdapter extends FragmentStatePagerAdapter {
    private DragViewPager mPager;
    private ArrayList<Fragment> mFragmentList;

    public ImagePagerAdapter(FragmentManager fm, List<String> datas,DragViewPager pager) {
        super(fm);
        mPager=pager;
        mPager.setAdapter(this);
        updateData(datas);
    }

    public void updateData(List<String> dataList) {
        ArrayList<Fragment> fragments = new ArrayList<>();
        for (int i = 0, size = dataList.size(); i < size; i++) {
            final ImageDetailFragment fragment = ImageDetailFragment.newInstance(dataList.get(i));
            fragment.setOnImageListener(new ImageDetailFragment.OnImageListener() {
                @Override
                public void onInit() {
                    View view = fragment.getView();
                    mPager.setCurrentShowView(view);
                }
            });
            fragments.add(fragment);
        }
        setViewList(fragments);
    }

    private void setViewList(ArrayList<Fragment> fragmentList) {
        if (mFragmentList != null) {
            mFragmentList.clear();
        }
        mFragmentList = fragmentList;
        notifyDataSetChanged();
    }

    @Override
    public int getCount() {
        return mFragmentList==null?0:mFragmentList.size();
    }

    public int getItemPosition(Object object) {
        return POSITION_NONE;
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }


}

要实现透明度变化的效果还需要对activity设置theme

<style name="translucent" parent="AppTheme">
        <item name="windowActionBar">false</item>
        <item name="windowNoTitle">true</item>
        <item name="android:windowIsTranslucent">true</item>
        <item name="android:windowBackground">@android:color/transparent</item>
</style>


<activity android:name=".ui.ImagePagerActivity"
            android:theme="@style/translucent"/>

在需要使用的页面只需要调用即可

ImagePagerActivity.startImagePage(MainActivity.this,
                        urls,pos,recyclerView.getLayoutManager().findViewByPosition(pos));

在整个demo中采用的转场动画，需要设置共享元素，因此在需要使用的页面需要设置如下：

首先设置转场动画的共享元素，因为跳转和返回时都会调用onMapSharedElements，需要判断bundle是否为空，bundle会在返回的时候在onActivityReenter获取到

//设置转场动画的共享元素，因为跳转和返回时都会调用onMapSharedElements，需要判断bundle是否为空
        setExitSharedElementCallback(new SharedElementCallback() {
            @Override
            public void onMapSharedElements(List<String> names, Map<String, View> sharedElements) {
                if (bundle!=null){
                    int index = bundle.getInt(ImagePagerActivity.STATE_POSITION,0);
                    sharedElements.clear();
                    sharedElements.put("img", recyclerView.getLayoutManager().findViewByPosition(index));
                    bundle=null;
                }
            }
        });

其次在返回的时候获取数据bundle

@Override
    public void onActivityReenter(int resultCode, Intent data) {
        super.onActivityReenter(resultCode, data);
        bundle = data.getExtras();
        int currentPosition = bundle.getInt(ImagePagerActivity.STATE_POSITION,0);
        //做相应的滚动
        recyclerView.scrollToPosition(currentPosition);
        //暂时延迟 Transition 的使用，直到我们确定了共享元素的确切大小和位置才使用
        //postponeEnterTransition后不要忘记调用startPostponedEnterTransition
        ActivityCompat.postponeEnterTransition(this);
        recyclerView.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
            @Override
            public boolean onPreDraw() {
                recyclerView.getViewTreeObserver().removeOnPreDrawListener(this);
                // TODO: figure out why it is necessary to request layout here in order to get a smooth transition.
                recyclerView.requestLayout();
                //共享元素准备好后调用startPostponedEnterTransition来恢复过渡效果
                ActivityCompat.startPostponedEnterTransition(MainActivity.this);
                return true;
            }
        });
    }

完整的调用页面的代码如下：

public class MainActivity extends AppCompatActivity {

    private RecyclerView recyclerView;

    private MainAdapter mainAdapter;

    //图片集合
    private ArrayList<String> urls;

    //存放返回时当前页码
    private Bundle bundle;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        urls=new ArrayList<>();
        //为了显示效果，重复添加了三次
        urls.add("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1524477979306&di=3eb07e9302606048abe13d7b6a2bc601&imgtype=0&src=http%3A%2F%2Fimg4.duitang.com%2Fuploads%2Fitem%2F201406%2F12%2F20140612211118_YYXAC.jpeg");
        urls.add("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1524133463580&di=1315bc4db30999f00b89ef79c3bb06e5&imgtype=0&src=http%3A%2F%2Fpic36.photophoto.cn%2F20150710%2F0005018721870517_b.jpg");
        urls.add("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1524133463575&di=6221f21bcb761675c5d161ebc53d5948&imgtype=0&src=http%3A%2F%2Fimg5.duitang.com%2Fuploads%2Fitem%2F201410%2F03%2F20141003112442_AkkuH.thumb.700_0.jpeg");

        urls.add("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1524477979306&di=3eb07e9302606048abe13d7b6a2bc601&imgtype=0&src=http%3A%2F%2Fimg4.duitang.com%2Fuploads%2Fitem%2F201406%2F12%2F20140612211118_YYXAC.jpeg");
        urls.add("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1524133463580&di=1315bc4db30999f00b89ef79c3bb06e5&imgtype=0&src=http%3A%2F%2Fpic36.photophoto.cn%2F20150710%2F0005018721870517_b.jpg");
        urls.add("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1524133463575&di=6221f21bcb761675c5d161ebc53d5948&imgtype=0&src=http%3A%2F%2Fimg5.duitang.com%2Fuploads%2Fitem%2F201410%2F03%2F20141003112442_AkkuH.thumb.700_0.jpeg");

        urls.add("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1524477979306&di=3eb07e9302606048abe13d7b6a2bc601&imgtype=0&src=http%3A%2F%2Fimg4.duitang.com%2Fuploads%2Fitem%2F201406%2F12%2F20140612211118_YYXAC.jpeg");
        urls.add("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1524133463580&di=1315bc4db30999f00b89ef79c3bb06e5&imgtype=0&src=http%3A%2F%2Fpic36.photophoto.cn%2F20150710%2F0005018721870517_b.jpg");
        urls.add("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1524133463575&di=6221f21bcb761675c5d161ebc53d5948&imgtype=0&src=http%3A%2F%2Fimg5.duitang.com%2Fuploads%2Fitem%2F201410%2F03%2F20141003112442_AkkuH.thumb.700_0.jpeg");
        initView();
    }

    private void initView() {
        recyclerView = (RecyclerView) findViewById(R.id.recycler);
        recyclerView.setLayoutManager(new GridLayoutManager(this, 2));
        mainAdapter = new MainAdapter(urls);
        mainAdapter.setOnItemClickListener(new MainAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(int pos) {
                ImagePagerActivity.startImagePage(MainActivity.this,
                        urls,pos,recyclerView.getLayoutManager().findViewByPosition(pos));
            }
        });
        recyclerView.setAdapter(mainAdapter);

        //设置转场动画的共享元素，因为跳转和返回都会调用，需要判断bundle是否为空
        setExitSharedElementCallback(new SharedElementCallback() {
            @Override
            public void onMapSharedElements(List<String> names, Map<String, View> sharedElements) {
                if (bundle!=null){
                    int index = bundle.getInt(ImagePagerActivity.STATE_POSITION,0);
                    sharedElements.clear();
                    sharedElements.put("img", recyclerView.getLayoutManager().findViewByPosition(index));
                    bundle=null;
                }
            }
        });
    }


    //返回的时候获取数据
    @Override
    public void onActivityReenter(int resultCode, Intent data) {
        super.onActivityReenter(resultCode, data);
        bundle = data.getExtras();
        int currentPosition = bundle.getInt(ImagePagerActivity.STATE_POSITION,0);
        //做相应的滚动
        recyclerView.scrollToPosition(currentPosition);
        //暂时延迟 Transition 的使用，直到我们确定了共享元素的确切大小和位置才使用
        //postponeEnterTransition后不要忘记调用startPostponedEnterTransition
        ActivityCompat.postponeEnterTransition(this);
        recyclerView.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
            @Override
            public boolean onPreDraw() {
                recyclerView.getViewTreeObserver().removeOnPreDrawListener(this);
                // TODO: figure out why it is necessary to request layout here in order to get a smooth transition.
                recyclerView.requestLayout();
                //共享元素准备好后调用startPostponedEnterTransition来恢复过渡效果
                ActivityCompat.startPostponedEnterTransition(MainActivity.this);
                return true;
            }
        });
    }
}

需要查看完整代码点击这里,喜欢的请给个star，谢谢

作者：JC_Hou
链接：https://www.jianshu.com/p/3c6384973db6
来源：简书
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