如何从Uri获取位图？

Question

如何从Uri中获取Bitmap对象(如果我成功将其存储在 /data/data/MYFOLDER/myimage.png或中file///data/data/MYFOLDER/myimage.png)以在我的应用程序中使用它？

有没有人知道如何实现这一目标？

Answer 1

这是正确的做法:

protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
    super.onActivityResult(requestCode, resultCode, data);
    if (resultCode == RESULT_OK)
    {
        Uri imageUri = data.getData();
        Bitmap bitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), imageUri);
    }
}

如果您需要加载非常大的图像,以下代码将在tile中加载它(避免大量内存分配):

BitmapRegionDecoder decoder = BitmapRegionDecoder.newInstance(myStream, false);  
Bitmap region = decoder.decodeRegion(new Rect(10, 10, 50, 50), null);

在这里看到答案

Answer 2

这是正确的做法,同时关注内存使用情况:

protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
  super.onActivityResult(requestCode, resultCode, data);
  if (resultCode == RESULT_OK)
  {
    Uri imageUri = data.getData();
    Bitmap bitmap = getThumbnail(imageUri);
  }
}

public static Bitmap getThumbnail(Uri uri) throws FileNotFoundException, IOException{
  InputStream input = this.getContentResolver().openInputStream(uri);

  BitmapFactory.Options onlyBoundsOptions = new BitmapFactory.Options();
  onlyBoundsOptions.inJustDecodeBounds = true;
  onlyBoundsOptions.inDither=true;//optional
  onlyBoundsOptions.inPreferredConfig=Bitmap.Config.ARGB_8888;//optional
  BitmapFactory.decodeStream(input, null, onlyBoundsOptions);
  input.close();

  if ((onlyBoundsOptions.outWidth == -1) || (onlyBoundsOptions.outHeight == -1)) {
    return null;
  }

  int originalSize = (onlyBoundsOptions.outHeight > onlyBoundsOptions.outWidth) ? onlyBoundsOptions.outHeight : onlyBoundsOptions.outWidth;

  double ratio = (originalSize > THUMBNAIL_SIZE) ? (originalSize / THUMBNAIL_SIZE) : 1.0;

  BitmapFactory.Options bitmapOptions = new BitmapFactory.Options();
  bitmapOptions.inSampleSize = getPowerOfTwoForSampleRatio(ratio);
  bitmapOptions.inDither = true; //optional
  bitmapOptions.inPreferredConfig=Bitmap.Config.ARGB_8888;//
  input = this.getContentResolver().openInputStream(uri);
  Bitmap bitmap = BitmapFactory.decodeStream(input, null, bitmapOptions);
  input.close();
  return bitmap;
}

private static int getPowerOfTwoForSampleRatio(double ratio){
  int k = Integer.highestOneBit((int)Math.floor(ratio));
  if(k==0) return 1;
  else return k;
}

Mark Ingram的帖子中的getBitmap()调用也调用了decodeStream(),因此您不会丢失任何功能.

参考文献:

• Android:获取原始图像的Uri,获取SD卡上的图像缩略图

• 处理大型位图

Answer 3

似乎MediaStore.Images.Media.getBitmap在API 29. 推荐的方法是使用ImageDecoder.createSource在API 28.

以下是获取位图的方法：

val bitmap = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
    ImageDecoder.decodeBitmap(ImageDecoder.createSource(requireContext().contentResolver, imageUri))
} else {
    MediaStore.Images.Media.getBitmap(requireContext().contentResolver, imageUri)
}

重要提示：ImageDecoder.decodeBitmap读取 EXIF 方向，Media.getBitmap不

Answer 4

try
{
    Bitmap bitmap = MediaStore.Images.Media.getBitmap(c.getContentResolver() , Uri.parse(paths));
}
catch (Exception e) 
{
    //handle exception
}

是的路径必须是这样的格式

file:///mnt/sdcard/filename.jpg

Answer 5

解决方案太简单了:

Bitmap bitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), uri);

Answer 6

 private void uriToBitmap(Uri selectedFileUri) {
        try {
            ParcelFileDescriptor parcelFileDescriptor =
                    getContentResolver().openFileDescriptor(selectedFileUri, "r");
            FileDescriptor fileDescriptor = parcelFileDescriptor.getFileDescriptor();
            Bitmap image = BitmapFactory.decodeFileDescriptor(fileDescriptor);


            parcelFileDescriptor.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

Answer 7

你可以像这样从uri中检索位图

Bitmap bitmap = null;
try {
    bitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), imageUri);
} catch (IOException e) {
    e.printStackTrace();
}

Answer 8

Uri imgUri = data.getData();
Bitmap bitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), imgUri);

Answer 9

Bitmap bitmap = null;
ContentResolver contentResolver = getContentResolver(); 
try {
    if(Build.VERSION.SDK_INT < 28) {
        bitmap = MediaStore.Images.Media.getBitmap(contentResolver, imageUri);
    } else {
        ImageDecoder.Source source = ImageDecoder.createSource(contentResolver, imageUri);
        bitmap = ImageDecoder.decodeBitmap(source);
    }
} catch (Exception e) {
    e.printStackTrace();
}

Answer 10

private fun setImage(view: ImageView, uri: Uri) {
        val stream = contentResolver.openInputStream(uri)
        val bitmap = BitmapFactory.decodeStream(stream)
        view.setImageBitmap(bitmap)
}