RecyclerView滑动窗口显示大尺寸广告位

翻看腾讯新闻App时,发现有个广告UI交互挺好玩的。先看图


gifhome_590x1280_5s.gif

gif图片可能有点卡,从视觉上看,有点像底部放了张海报,上层列表有个窗口透视过去,随着滚动窗口看到底部海报不同部分。
撸起袖子开干。
一般自定义View相关的,第一步就是做拆解。首先,如果从排版看,最外层View不是RecyclerView就是ListView

方案一
WX20191226-170617@2x.png

如图:底部是一个ImageView,上层是一个列表RecyclerView,设置列表背景为透明的,根据item type加载不同ViewHolder,当需要展示底部广告时,其ViewHolder itemView背景为透明的,即可满足UI的效果。
不足:布局不够简化,数据填充不灵活,如果屏幕内出现多个相关类型的窗口时,不满足加载不同的海报。

方案二

如果广告窗口是ImageView,按照大图的局部加载显示思想,当窗口ViewHolder向上滑,图片显示下部分区域,反之,窗口ViewHolder往下滑时,图片显示上部分。


fea07d33-ed4b-4a44-8b54-cfd2c4e40a85.gif

代码实现:

public class ScrollWindowImageView extends AppCompatImageView {
     private boolean initialized;
     private Matrix matrix;
     private boolean isScrollDown = true;
     private float translate;

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

     public ScrollWindowImageView(Context context, AttributeSet attrs) {
          this(context, attrs, 0);
     }

     public ScrollWindowImageView(Context context, AttributeSet attrs, int defStyleAttr) {
         super(context, attrs, defStyleAttr);
         setScaleType(ScaleType.MATRIX);
     }

     @Override
     protected void onSizeChanged(int w, int h, int oldw, int oldh) {
         super.onSizeChanged(w, h, oldw, oldh);
         initialized = true;
         initImage();
     }

     private void initImage() {
         final Drawable drawable = getDrawable();
         if (!initialized || drawable == null) {
             return;
         }
         final int viewWidth = getWidth();
         final int viewHeight = getHeight();
         final int drawableWidth = drawable.getIntrinsicWidth();
         final int drawableHeight = drawable.getIntrinsicHeight();
         float scaleX = (float) viewWidth / drawableWidth;
         matrix = getImageMatrix();
         matrix.setScale(scaleX, scaleX);
         matrix.postTranslate(0, -(drawableHeight * scaleX - viewHeight));
         setImageMatrix(matrix);
     }

     public void scrollWindow(float scrollY) {
         final Drawable drawable = getDrawable();
         if (!initialized || drawable == null) {
             return;
         }
         float[] imageMatrixValues = new float[9];
         matrix.getValues(imageMatrixValues);
         float scale = Math.abs(imageMatrixValues[0]) + Math.abs(imageMatrixValues[1]);
         matrix.setScale(scale, scale);
         float translate = scrollY - (drawable.getIntrinsicHeight() * scale - getHeight());
         if (translate > 0) {
             translate = 0;
         }
         matrix.postTranslate(0, translate);
         setImageMatrix(matrix);
     }

     private final Runnable runnable = new Runnable() {
         @Override
         public void run() {
             if (translate > getDrawable().getIntrinsicHeight() - DensityUtil.dp2px(getContext(), 200)) {
                 isScrollDown = false;
             } else if (translate < -DensityUtil.dp2px(getContext(), 200)) {
                 isScrollDown = true;
             }
             if (isScrollDown) {
                 translate += 10;
             } else {
                 translate -= 10;
             }
             LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) getLayoutParams();
             params.topMargin = (int) translate;
             setLayoutParams(params);
             scrollWindow(-translate);
             HandlerUtil.runOnUiThreadDelay(this, 16);
         }
     };

    public void show() {
        HandlerUtil.runOnUiThreadDelay(runnable, 16);
   }
}

接下来就是拼接了,ScrollWindowImageView作为RecyclerView ViewHolder的ItemView,当滑动时,将滑动响应传递给ScrollWindowImageView,若向上滑,ImageView图像Bitmap往下移动

public class ScrollWindowImageView extends AppCompatImageView {
    private boolean initialized;
    private Matrix matrix;
    public ScrollWindowImageView(Context context) {
        this(context, null);
    }

    public ScrollWindowImageView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public ScrollWindowImageView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        setScaleType(ScaleType.MATRIX);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        initialized = true;
        initImage();
    }

    private void initImage() {
         final Drawable drawable = getDrawable();
         if (!initialized || drawable == null) {
             return;
         }
         final int viewWidth = getWidth();
         final int viewHeight = getHeight();
         final int drawableWidth = drawable.getIntrinsicWidth();
         final int drawableHeight = drawable.getIntrinsicHeight();
         float scaleX = (float) viewWidth / drawableWidth;
         matrix = getImageMatrix();
         matrix.setScale(scaleX, scaleX);
         matrix.postTranslate(0, -(drawableHeight * scaleX - viewHeight));
         setImageMatrix(matrix);
     }

     public void scrollWindow(float scrollY) {
         final Drawable drawable = getDrawable();
         if (!initialized || drawable == null) {
             return;
         }
         float[] imageMatrixValues = new float[9];
         matrix.getValues(imageMatrixValues);
         float scale = Math.abs(imageMatrixValues[0]) + Math.abs(imageMatrixValues[1]);
         matrix.setScale(scale, scale);
         float translate = scrollY - (drawable.getIntrinsicHeight() * scale - getHeight());
         if (translate > 0) {
             translate = 0;
         }
         matrix.postTranslate(0, translate);
         setImageMatrix(matrix);
     }
}


public class ScrollWindowActivity extends BaseActivity {

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_scroll_window);
        RecyclerView recyclerView = findViewById(R.id.scroll_window_recycler_view);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        ScrollWindowAdapter adapter = new ScrollWindowAdapter(this);
        recyclerView.setAdapter(adapter);
        recyclerView.addOnScrollListener(scrollListener);
        adapter.notifyDataSetChanged();
    }

    private RecyclerView.OnScrollListener scrollListener = new RecyclerView.OnScrollListener() {
        @Override
        public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
            super.onScrollStateChanged(recyclerView, newState);
        }

        @Override
        public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);
            LinearLayoutManager layoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
            int childCount = layoutManager.getChildCount();
            for (int i = 0; i < childCount; i++) {
                View view = layoutManager.getChildAt(i);
                Object tag = view.getTag();
                if (tag instanceof ScrollWindowViewHolder) {
                    ScrollWindowViewHolder holder = (ScrollWindowViewHolder) tag;
                    holder.onScrolled(recyclerView, view, dx, dy);
                }
            }
        }
    };

    static class ScrollWindowAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
        private LayoutInflater inflater;

        ScrollWindowAdapter(Context context) {
            inflater = LayoutInflater.from(context);
        }

        @NonNull
        @Override
        public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            if (viewType == 1) {
                return new ScrollWindowViewHolder(inflater.inflate(R.layout.item_scroll_ad_window, parent, false));
            }
            return new NormalViewHolder(inflater.inflate(R.layout.item_scroll_normal, parent, false));
        }

        @Override
        public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
            if (position == 6) {
                ((ScrollWindowViewHolder) holder).imageView.setImageResource(R.mipmap.car);
            }
        }

        @Override
        public int getItemCount() {
            return 21;
        }

        @Override
        public int getItemViewType(int position) {
            if (position == 6) {
                return 1;
            }
            return 0;
        }
    }

    static class NormalViewHolder extends RecyclerView.ViewHolder {
        NormalViewHolder(@NonNull View itemView) {
            super(itemView);
        }
    }

    static class ScrollWindowViewHolder extends RecyclerView.ViewHolder {
        private ScrollWindowImageView imageView;

        ScrollWindowViewHolder(@NonNull View itemView) {
            super(itemView);
            itemView.setTag(this);
            imageView = itemView.findViewById(R.id.ad_window_image_view);
        }

        void onScrolled(RecyclerView recyclerView, View itemView, int dx, int dy) {
            int parentBottom = recyclerView.getBottom();
            int itemBottom = itemView.getBottom();
            if (itemBottom < parentBottom) {
                int scrollY = parentBottom - itemBottom;
                imageView.scrollWindow(scrollY);
            }
        }
    }
}
19a6735c-581f-401c-9c21-f8eaea29280d.gif

此方案支持屏幕内有多个item为广告位,数据配置填充灵活


16d33759-758c-42a7-9fc1-7c9a3058dea5.gif

方案和实现都比较简单,不过这种交互体验还是挺好的。