Question

我找到了很多关于如何加载大型位图并避免outofmemory异常的文档。但问题是我必须从我的MediaStore.Images.media中获取图像所以经典谷歌文档中指出的decodeFile(path,options)对我不起作用

如下所示，我取消了行// Bitmap photo= Mediastore.Images，即触发内存不足的行Bitmap bm=BitmapFactory.decodeFile(selectedImageToUri,options)。在另一边补充行null返回selectedImageToUri，虽然编译器可以看到BitMap photo中的路径（表示图片所在的内容提供者）而不是选项值，我设置为8，因为我想要缩放所有图像

我的问题是如何在bm中插入引用用户在库中选择的图像的位图。行@Override public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable final Bundle savedInstanceState) { if (flagVariable) { if (selectedImageToUri != null) { // BitMap photo = MediaStore.Images.Media.getBitmap(getActivity().getContentResolver(), Uri.parse(selectedImageToUri)); final BitmapFactory.Options options= new BitmapFactory.Options(); options.inSampleSize=8; Bitmap bm = BitmapFactory.decodeFile(selectedImageToUri, options); pic = new BitmapDrawable(bm); getActivity().getWindow().setBackgroundDrawable(pic); } else { getDefaultImageBackground(inflater, container); } hiddenList = inflater.inflate(R.layout.fragment_as_list_layout_temp, container, false); } else { getDefaultImageBackground(inflater, container); } listView = (ListView) hiddenList.findViewById(R.id.list_hidden);中的行不会返回null并且工作得非常好，但是我已经取消注释，因为在我更改了几个图像之后会给我一些内存异常。

SELECT 
    [Measures].[Store sales]
  * 
    {
      [Occupation].[Occupation].MEMBERS * {[Essai].[All]}
     ,
      {[Occupation].[All]} * [Essai].[Essai].MEMBERS
    } ON COLUMNS
 ,{[Product].[Product Family].MEMBERS} ON ROWS
FROM test;

Answer 1

MediaStore.getBitmap只是一种简单的便利方法，它看起来像这样：

public static final Bitmap getBitmap(ContentResolver cr, Uri url)
                throws FileNotFoundException, IOException {
    InputStream input = cr.openInputStream(url);
    Bitmap bitmap = BitmapFactory.decodeStream(input);
    input.close();
    return bitmap;
}

您可以根据此方法创建自己的方法options，并在BitmapFactory上调用不同的重载：

public static final Bitmap getBitmap(ContentResolver cr,
                                     Uri url,
                                     BitmapFactory.Options options)
                throws FileNotFoundException, IOException {
    InputStream input = cr.openInputStream(url);
    Bitmap bitmap = BitmapFactory.decodeStream(input, null, options);
    input.close();
    return bitmap;
}

用法：

final BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 8;

Bitmap bm = getBitmap(getActivity().getContentResolver(),
                      Uri.parse(selectedImageToUri),
                      options);

Answer 2

我在这个问题上花了很多时间，但是没有人会给我确切的答案，最后我解决了。首先创建方法并提供Image URI作为参数，这将基本上返回位图，我计算图像大小，我们可以管理内存和图像，并以位图形式获得精确的图像。

你甚至可以显示5000×8000和12MiB图片，没有任何错误代码被测试只需复制粘贴在你的班级并享受。

使用

Bitmap mBitmap = getPhoto(MYIMAGEURI);

为方法提供URI并获取位图

Bitmap getPhoto(Uri selectedImage) { DisplayMetrics metrics = new DisplayMetrics(); getWindowManager().getDefaultDisplay().getMetrics(metrics); int height = metrics.heightPixels; int width = metrics.widthPixels; Bitmap photoBitmap = null; InputStream inputStream = null; try { inputStream = getContentResolver().openInputStream(selectedImage); } catch (FileNotFoundException e) { e.printStackTrace(); } BitmapFactory.Options bitmapOptions = new BitmapFactory.Options(); bitmapOptions.inJustDecodeBounds = true; BitmapFactory.decodeStream(inputStream, null, bitmapOptions); int imageWidth = bitmapOptions.outWidth; int imageHeight = bitmapOptions.outHeight; @SuppressWarnings("unused") InputStream is = null; try { is = getContentResolver().openInputStream(selectedImage); } catch (FileNotFoundException e) { e.printStackTrace(); } float scale = 1.0f; if (imageWidth < imageHeight) { if (imageHeight > width * 1.0f) { scale = width * 1.0f / (imageHeight * 1.0f); } } else { if (imageWidth > width * 1.0f) { scale = width * 1.0f / (imageWidth * 1.0f); } } photoBitmap = decodeSampledBitmapFromResource(this, selectedImage, (int) (imageWidth * scale), (int) (imageHeight * scale)); return photoBitmap; }

使用图像尺寸解码位图示例

public static Bitmap decodeSampledBitmapFromResource(Context context, Uri uri, int reqWidth, int reqHeight) { // First decode with inJustDecodeBounds=true to check dimensions final BitmapFactory.Options options = new BitmapFactory.Options(); options.inJustDecodeBounds = true; InputStream is = null; try { is = context.getContentResolver().openInputStream(uri); } catch (FileNotFoundException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } BitmapFactory.decodeStream(is, null, options); // Calculate inSampleSize options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight); // Decode editBitmap with inSampleSize set options.inJustDecodeBounds = false; InputStream inputs = null; try { inputs = context.getContentResolver().openInputStream(uri); } catch (FileNotFoundException e) { e.printStackTrace(); } return BitmapFactory.decodeStream(inputs, null, options); }

计算样本量

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 = Math.min(heightRatio, widthRatio); // inSampleSize = heightRatio < widthRatio ? heightRatio : // widthRatio; } return inSampleSize; }

或者可以使用 manifiest.xml 中的一行代码解决在应用程序标签中使用此

android:largeHeap="true"

大位图的outofmemory异常

2 个答案: