android – RecyclerView消失的图像

我想要创建的是一个水平滚动图库.我有一个RecyclerView(支持22.0.0).我遇到的问题是,当我滚动到最后然后向后滚动时,通常会丢失一个图像,有时会丢失两个图像.奇怪的是,当我不停地来回扫动时,可能会丢失不同的图像.这是项目的布局：

<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="160dp">

<ImageView
    android:id="@+id/product_variation_image"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:scaleType="centerCrop"
    android:layout_gravity="center"/>

这是Adaper：

public class TestAdapter extends RecyclerView.Adapter<TestAdapter.ViewHolder> {
private String[] mDataset;

public static class ViewHolder extends RecyclerView.ViewHolder {

    public ImageView mImageView;
    public ViewHolder(View v) {
        super(v);
        mImageView = (ImageView) v.findViewById(R.id.product_variation_image);
    }
}

public TestAdapter(String[] myDataset) {
    mDataset = myDataset;
}

@Override
public TestAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,int viewType) {
    // create a new view
    View v = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.variaton_list_item,parent,false);
    ViewHolder vh = new ViewHolder(v);
    return vh;
}

@Override
public void onBindViewHolder(ViewHolder holder,int position) {

    holder.mImageView.setImageDrawable(null);
    String url = mDataset[position];
    Log.i("TEST","position = " + position);
    ((MainActivity)MainActivity.getInstance()).imageDownloader.download(url,holder.mImageView);
}

@Override
public int getItemCount() {
    return mDataset.length;
}

下载方法从URL获取图像,或者如果已经缓存,则从内存中获取图像.这适用于所有其他布局,例如ListView或GridView.这是我在片段中设置它的代码：

final LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
    layoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
    mRecyclerView.setLayoutManager(layoutManager);

这是在onCreateView方法中.当我获取网址时,我填充它们并使用以下方法设置适配器：

myDataset[i] = imageURL; // for each image       
  mAdapter = new TestAdapter(myDataset);
  mRecyclerView.setAdapter(mAdapter);

有趣的是适配器中onBindViewHolder方法中的行,我记录位置.我发现没有显示图像的单元格是没有调用此方法.就像它出于某种原因跳过那个细胞一样.更奇怪的是,如果我按住一个单元格并继续从左向右滑动,如果一个单元格离开屏幕然后又重新进入,那么它的图像就会再次被调用onBindViewHolder方法.

解决方法

我认为不重要的一个类是造成这个问题的一个类.我不确定是什么原因,但它存在于我用于从BitmapFun示例获得的回收的自定义ImageView类中.

public class RecyclingImageView extends ImageView {

    public RecyclingImageView(Context context) {
        super(context);
    }

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

    /**
     * @see android.widget.ImageView#onAttachedToWindow()
     */
    @Override
    protected void onAttachedToWindow() {}

    /**
     * @see android.widget.ImageView#onDetachedFromWindow()
     */
    @Override
    protected void onDetachedFromWindow() {
        // This has been detached from Window,so clear the drawable

        setImageDrawable(null); 

        super.onDetachedFromWindow();
    }

    /**
     * @see android.widget.ImageView#setImageDrawable(android.graphics.drawable.Drawable)
     */
    @Override
    public void setImageDrawable(Drawable drawable) {
        // Keep hold of prevIoUs Drawable
        final Drawable prevIoUsDrawable = getDrawable();

        // Call super to set new Drawable
        super.setImageDrawable(drawable);

        // Notify new Drawable that it is being displayed
        notifyDrawable(drawable,true);

        // Notify old Drawable so it is no longer being displayed
        notifyDrawable(prevIoUsDrawable,false);
    }

    /**
     * Notifies the drawable that it's displayed state has changed.
     *
     * @param drawable
     * @param isDisplayed
     */
    private static void notifyDrawable(Drawable drawable,final boolean isDisplayed) {
        if (drawable instanceof RecyclingBitmapDrawable) {
            // The drawable is a CountingBitmapDrawable,so notify it
            ((RecyclingBitmapDrawable) drawable).setIsDisplayed(isDisplayed);
        } else if (drawable instanceof LayerDrawable) {
            // The drawable is a LayerDrawable,so recurse on each layer
            LayerDrawable layerDrawable = (LayerDrawable) drawable;
            for (int i = 0,z = layerDrawable.getNumberOfLayers(); i < z; i++) {
                notifyDrawable(layerDrawable.getDrawable(i),isDisplayed);
            }
        }
    }

}

当我用普通的ImageView替换它时,我不再遇到问题.

android – RecyclerView消失的图像

解决方法

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