java.lang.OutOfMemoryError 在 vi​​ewFlipper 中显示图像列表时

Question

我正在尝试在我的应用程序中使用动态磁贴图像。我在某些设备 (API>22) 上测试了该功能，它们可以正常工作。但是现在我正在 API 22 上进行测试，但我在标题中遇到了错误。我搜索了该站点，发现它特别有用 OutOfMemoryExceptionGridView。但是我正在将我的图像（直接从 res 文件夹）加载到一个数组，然后使用 viewflipper 制作幻灯片

我如何更改我的代码块（以修复主 OOME），因为我上面链接的内容使用位图，而我直接调用 res id。

这是我的代码：

@Override
    public View onCreateView(LayoutInflater inflater, final ViewGroup container,
                             Bundle savedInstanceState) {

       int[] images = {R.drawable.img1, R.drawable.img2, R.drawable.img3}; //store images into array
        viewFlipper = view.findViewById(R.id.firstTile); //main tile to have slideshow
         for (int image : images) {
            flipperImages(image); //performs the slideshow per image
        }
}
 public void flipperImages(int image) {
        ImageView imageViewFirstTile = new ImageView(getContext());
        imageViewFirstTile.setBackgroundResource(image);
        viewFlipper.addView(imageViewFirstTile);
        viewFlipper.setFlipInterval(12500);
        viewFlipper.setAutoStart(true);
        viewFlipper.setInAnimation(getContext(), android.R.anim.slide_in_left);
        viewFlipper.setOutAnimation(getContext(), android.R.anim.slide_out_right);
    }

如何修复此实现的主要错误（直接调用图像的 res id）？

Answer 1

如果可以缩小图像以避免加载全尺寸图像，我会考虑将其作为第一步。如果显示它们的 window 只是大小的一小部分，则无需将全尺寸位图加载到内存中。在您当前的方法中，图像未被二次采样，因此整个 Bitmap 以其完整大小加载到内存中。所以你的内存中有 3 个全尺寸 Bitmap。

要对图像进行子采样，请参见以下代码。 （来源：https://developer.android.com/topic/performance/graphics/load-bitmap）

/* reqWidth and reqHeight would be the dimensions of your ImageView or some other preferred dimensions. For example, if your Bitmap is 500 X 500 and your ViewFlipper/ImageView is only 100 X 100, passing 100 as reqWidth and 100 as reqHeight will subsample the image until it's dimensions are close to the 100 X 100. This will largely shrink the size loaded into memory. */ 
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);
}


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;
}