如何解决Android 相机 Exif 没有方向数据但图像已旋转
我正在使用以下辅助类来处理相机图像的采样和旋转。
object CaptureImageHelper {
/**
* This method is responsible for solving the rotation issue if exist. Also scale the images to
* 1024x1024 resolution
*
* @param context The current context
* @param selectedImage The Image URI
* @return Bitmap image results
* @throws IOException
*/
@Throws(IOException::class)
fun handleSamplingAndRotationBitmap(
context: Context,selectedImage: Uri?,isFrontCamera: Boolean
): Bitmap? {
val MAX_HEIGHT = 1024
val MAX_WIDTH = 1024
// First decode with inJustDecodeBounds=true to check dimensions
val options = BitmapFactory.Options()
options.inJustDecodeBounds = true
var imagestream: InputStream = context.getContentResolver().openInputStream(selectedImage!!)!!
BitmapFactory.decodeStream(imagestream,null,options)
imagestream.close()
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options,MAX_WIDTH,MAX_HEIGHT)
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false
imagestream = context.getContentResolver().openInputStream(selectedImage!!)!!
var img = BitmapFactory.decodeStream(imagestream,options)
img = rotateImageIfrequired(img!!,selectedImage,isFrontCamera)
return img
}
/**
* Calculate an inSampleSize for use in a [BitmapFactory.Options] object when decoding
* bitmaps using the decode* methods from [BitmapFactory]. This implementation calculates
* the closest inSampleSize that will result in the final decoded bitmap having a width and
* height equal to or larger than the requested width and height. This implementation does not
* ensure a power of 2 is returned for inSampleSize which can be faster when decoding but
* results in a larger bitmap which isn't as useful for caching purposes.
*
* @param options An options object with out* params already populated (run through a decode*
* method with inJustDecodeBounds==true
* @param reqWidth The requested width of the resulting bitmap
* @param reqHeight The requested height of the resulting bitmap
* @return The value to be used for inSampleSize
*/
private fun calculateInSampleSize(
options: BitmapFactory.Options,reqWidth: Int,reqHeight: Int
): Int {
// Raw height and width of image
val height = options.outHeight
val width = options.outWidth
var inSampleSize = 1
if (height > reqHeight || width > reqWidth) {
// Calculate ratios of height and width to requested height and width
val heightRatio =
Math.round(height.toFloat() / reqHeight.toFloat())
val widthRatio =
Math.round(width.toFloat() / reqWidth.toFloat())
// 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 = if (heightRatio < widthRatio) heightRatio else widthRatio
// This offers some additional logic in case the image has a strange
// aspect ratio. For example,a panorama may have a much larger
// width than height. In these cases the total pixels might still
// end up being too large to fit comfortably in memory,so we should
// be more aggressive with sample down the image (=larger inSampleSize).
val totalPixels = width * height.toFloat()
// Anything more than 2x the requested pixels we'll sample down further
val totalReqPixelsCap = reqWidth * reqHeight * 2.toFloat()
while (totalPixels / (inSampleSize * inSampleSize) > totalReqPixelsCap) {
inSampleSize++
}
}
return inSampleSize
}
/**
* Rotate an image if required.
*
* @param img The image bitmap
* @param selectedImage Image URI
* @return The resulted Bitmap after manipulation
*/
@Throws(IOException::class)
private fun rotateImageIfrequired(
img: Bitmap,selectedImage: Uri,isFrontCamera: Boolean
): Bitmap? {
val ei = ExifInterface(selectedImage.path!!)
val orientation: Int =
ei.getAttributeInt(ExifInterface.TAG_ORIENTATION,ExifInterface.ORIENTATION_norMAL)
return when (orientation) {
ExifInterface.ORIENTATION_ROTATE_90 -> rotateImage(img,90,isFrontCamera)
ExifInterface.ORIENTATION_ROTATE_180 -> rotateImage(img,180,isFrontCamera)
ExifInterface.ORIENTATION_ROTATE_270 -> rotateImage(img,270,isFrontCamera)
else -> img
}
}
private fun rotateImage(
img: Bitmap,degree: Int,isFrontCamera: Boolean
): Bitmap? {
val matrix = Matrix()
if(isFrontCamera) {
val matrixMirrorY = Matrix()
val mirrorY = floatArrayOf(-1f,0f,1f,1f)
matrixMirrorY.setValues(mirrorY)
matrix.postConcat(matrixMirrorY)
matrix.preRotate(270f)
} else {
matrix.postRotate(degree.toFloat())
}
val rotatedImg =
Bitmap.createBitmap(img,img.width,img.height,matrix,true)
img.recycle()
return rotatedImg
}
}
调用助手类
val bitmap = CaptureImageHelper.handleSamplingAndRotationBitmap(requireContext(),Uri.fromFile(cameraimage!!),false)
我遇到的问题是随机的。大多数情况下,如果我在声明下方获得旋转图像
ei.getAttributeInt(ExifInterface.TAG_ORIENTATION,ExifInterface.ORIENTATION_norMAL)
返回 ExifInterface.ORIENTATION_ROTATE_90 很好,代码正确旋转该图像。但有时图像被旋转但它 Exif getAttributeInt 返回 ExifInterface.ORIENTATION_norMAL。我相信这意味着没有针对此图像的 Exif/Orientation 数据,它返回默认值。
public int getAttributeInt(@NonNull String tag,int defaultValue) {
if (tag == null) {
throw new NullPointerException("tag shouldn't be null");
}
ExifAttribute exifAttribute = getExifAttribute(tag);
if (exifAttribute == null) {
return defaultValue;
}
try {
return exifAttribute.getIntValue(mExifByteOrder);
} catch (NumberFormatException e) {
return defaultValue;
}
}
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