android - 在回收站内的 cardview 中滑动图像的最佳方法是什么？

Question

我有一个带有 Cardview 的 RecyclerView。我想在这个 CardView 中滑动图像，就像在 OLX 应用程序中一样。最好的方法是什么？我考虑将 viewpager 放在 cardview 中。可以吗，或者我应该试试别的东西？

我用 ViewPager 做到了，但它看起来太慢了。这是 viewpager 适配器的一部分。

 @Override
public Object instantiateItem(ViewGroup collection, int position) {

    LayoutInflater inflater = LayoutInflater.from(mContext);
    ViewGroup layout = (ViewGroup) inflater.inflate(R.layout.viewpager_custom, collection, false);
    collection.addView(layout);

    ImageView image = (ImageView) layout.findViewById(R.id.viewPagerImageView);
    image.setImageResource(mPics[position]);

    return layout;
}

Answer 1

你走对了路。

只做一件事加载压缩位图而不是未压缩位图。您直接将位图资源设置为 ImageView 。要么使用像 Picasso 这样的库 https://github.com/square/picasso/

或使用 google 的官方资源来高效加载大型位图。

首先在你的activity中复制这个方法:

public static int calculateInSampleSize(
            BitmapFactory.Options options, int reqWidth, int reqHeight) {
    // Raw height and width of image
    final int height = options.outHeight;
    final int width = options.outWidth;
    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {

        final int halfHeight = height / 2;
        final int halfWidth = width / 2;

        // Calculate the largest inSampleSize value that is a power of 2 and keeps both
        // height and width larger than the requested height and width.
        while ((halfHeight / inSampleSize) > reqHeight
                && (halfWidth / inSampleSize) > reqWidth) {
            inSampleSize *= 2;
        }
    }

    return inSampleSize;
}

然后这个解码位图的方法:

public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId,
        int reqWidth, int reqHeight) {

    // First decode with inJustDecodeBounds=true to check dimensions
    final BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeResource(res, resId, options);

    // Calculate inSampleSize
    options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

    // Decode bitmap with inSampleSize set
    options.inJustDecodeBounds = false;
    return BitmapFactory.decodeResource(res, resId, options);
}

然后像这样加载你的位图:

@Override
public Object instantiateItem(ViewGroup collection, int position) {

    LayoutInflater inflater = LayoutInflater.from(mContext);
    ViewGroup layout = (ViewGroup) inflater.inflate(R.layout.viewpager_custom, collection, false);
    collection.addView(layout);

    ImageView image = (ImageView) layout.findViewById(R.id.viewPagerImageView);
    image.setImageBitmap(
    decodeSampledBitmapFromResource(getResources(), R.id.myimage, reqwidth, reqheight));

    return layout;
}