安卓位图OutOfMemoryError

Question

我的VSD220里有一个OutOfMemoryError (它是一个22英寸的安卓一体机)

for (ImageView img : listImages) {
            System.gc();

            Bitmap myBitmap = BitmapFactory.decodeFile(path);
            img.setImageBitmap(myBitmap);
            img.setOnClickListener(this);
        }

我真的不知道该怎么办，因为这张图片低于最大分辨率。图像大小约为(1000x1000)，显示器大小为1920x1080。

有什么帮助吗？(这个foreach循环大约有20个元素，在6个或7个循环之后就会中断。)

非常感谢。

埃兹奎尔。

Answer 1

您应该看看Managing Bitmap Memory的培训文档。根据您的操作系统版本，您可以使用不同的技术来管理更多的位图，但您可能无论如何都必须更改您的代码。

特别是，您可能不得不使用"Load a Scaled Down Version into Memory“中代码的修正版本，但我至少发现这一节特别有用：

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) {

        // Calculate ratios of height and width to requested height and width
        final int heightRatio = Math.round((float) height / (float) reqHeight);
        final int widthRatio = Math.round((float) width / (float) reqWidth);

        // Choose the smallest ratio as inSampleSize value, this will guarantee
        // a final image with both dimensions larger than or equal to the
        // requested height and width.
        inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
    }

    return inSampleSize;
}



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);
}

使用此方法，可以轻松地将任意大小的位图加载到显示100x100像素缩略图的ImageView中，如下面的示例代码所示：

mImageView.setImageBitmap(
decodeSampledBitmapFromResource(getResources(), R.id.myimage, 100, 100));

Answer 2

您确定要将同一位图加载20次吗？你不想加载它一次并将它设置在循环中吗？

尽管如此，无论屏幕分辨率如何，加载1000x1000像素的图像都不能保证正常工作。请记住，1000x1000像素的图像占用1000x1000x4字节=~4MB (如果将其作为ARGB_8888加载)。如果你的堆内存是碎片的/太小，你可能没有足够的空间加载位图。您可能希望研究一下BitmapFactory.Options类，并尝试使用inPreferredConfig和inSampleSize

我建议你要么使用DigCamara的建议，决定一个大小，然后加载一个接近这个大小的下采样图像(我说几乎是因为使用这种技术你不会得到确切的大小)，要么尝试加载完整大小的图像，然后递归增加样本大小(为了获得最佳结果，递归增加2倍)，直到达到最大样本大小或加载图像：

/**
 * Load a bitmap from a stream using a specific pixel configuration. If the image is too
 * large (ie causes an OutOfMemoryError situation) the method will iteratively try to
 * increase sample size up to a defined maximum sample size. The sample size will be doubled
 * each try since this it is recommended that the sample size should be a factor of two
 */
public Bitmap getAsBitmap(InputStream in, BitmapFactory.Config config, int maxDownsampling) {
    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inSampleSize = 1;   
    options.inPreferredConfig = config;
    Bitmap bitmap = null;
    // repeatedly try to the load the bitmap until successful or until max downsampling has been reached
    while(bitmap == null && options.inSampleSize <= maxDownsampling) {
        try {
            bitmap = BitmapFactory.decodeStream(in, null, options);
            if(bitmap == null) {
                // not sure if there's a point in continuing, might be better to exit early
                options.inSampleSize *= 2;
            }
        }
        catch(Exception e) {
            // exit early if we catch an exception, for instance an IOException
            break;
        }
        catch(OutOfMemoryError error) {
            // double the sample size, thus reducing the memory needed by 50%
            options.inSampleSize *= 2;
        }
    }
    return bitmap;
}