我正在捕捉图像并将其设置为图像视图。
public void captureImage() {
Intent intentCamera = new Intent("android.media.action.IMAGE_CAPTURE");
File filePhoto = new File(Environment.getExternalStorageDirectory(), "Pic.jpg");
imageUri = Uri.fromFile(filePhoto);
MyApplicationGlobal.imageUri = imageUri.getPath();
intentCamera.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
startActivityForResult(intentCamera, TAKE_PICTURE);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intentFromCamera) {
super.onActivityResult(requestCode, resultCode, intentFromCamera);
if (resultCode == RESULT_OK && requestCode == TAKE_PICTURE) {
if (intentFromCamera != null) {
Bundle extras = intentFromCamera.getExtras();
if (extras.containsKey("data")) {
bitmap = (Bitmap) extras.get("data");
}
else {
bitmap = getBitmapFromUri();
}
}
else {
bitmap = getBitmapFromUri();
}
// imageView.setImageBitmap(bitmap);
imageView.setImageURI(imageUri);
}
else {
}
}
public Bitmap getBitmapFromUri() {
getContentResolver().notifyChange(imageUri, null);
ContentResolver cr = getContentResolver();
Bitmap bitmap;
try {
bitmap = android.provider.MediaStore.Images.Media.getBitmap(cr, imageUri);
return bitmap;
}
catch (Exception e) {
e.printStackTrace();
return null;
}
}
但问题是，某些设备上的图像每次旋转时。例如，在三星设备上，它工作得很好，但在索尼Xperia上，图像旋转了90度，在东芝Thrive(平板电脑)上旋转了180度。
这是Xamarin。Android版本:
来自@Jason Robinson的回答:
Bitmap rotate(Bitmap bitmap, int angle)
{
var matrix = new Matrix();
matrix.PostRotate(angle);
return Bitmap.CreateBitmap(bitmap, 0, 0, bitmap.Width, bitmap.Height, matrix, true);
}
Bitmap rotateIfRequired(Bitmap bitmap, string imagePath)
{
var ei = new ExifInterface(imagePath);
var orientation = ei.GetAttributeInt(ExifInterface.TagOrientation, (int)Android.Media.Orientation.Undefined);
switch (orientation)
{
case (int)Android.Media.Orientation.Rotate90: return rotate(bitmap, 90);
case (int)Android.Media.Orientation.Rotate180: return rotate(bitmap, 180);
case (int)Android.Media.Orientation.Rotate270: return rotate(bitmap, 270);
default: return bitmap;
}
}
然后calculateInSampleSize方法:
int calculateInSampleSize(BitmapFactory.Options options, int reqW, int reqH)
{
float h = options.OutHeight;
float w = options.OutWidth;
var inSampleSize = 1;
if (h > reqH || w > reqW)
{
if (reqH == 0) inSampleSize = (int)Math.Floor(w / reqW);
else if (reqW == 0) inSampleSize = (int)Math.Floor(h / reqH);
else
{
var hRatio = (int)Math.Floor(h / reqH);
var wRatio = (int)Math.Floor(w / reqW);
inSampleSize = false ? Math.Max(hRatio, wRatio) : Math.Min(hRatio, wRatio);
}
}
return inSampleSize;
}
来自@Sami Eltamawy的回答:
Bitmap handleSamplingAndRotationBitmap(string imagePath)
{
var maxHeight = 1024;
var maxWidth = 1024;
var options = new BitmapFactory.Options();
options.InJustDecodeBounds = true;
BitmapFactory.DecodeFile(imagePath, options);
options.InSampleSize = calculateInSampleSize(options, maxWidth, maxHeight);
options.InJustDecodeBounds = false;
var bitmap = BitmapFactory.DecodeFile(imagePath, options);
bitmap = rotateIfRequired(bitmap, imagePath);
return bitmap;
}
大多数手机摄像头都是横拍的，也就是说如果你用竖拍，拍出来的照片会旋转90度。在这种情况下，相机软件应该填充Exif数据，以显示照片的方向。
请注意，下面的解决方案取决于填充Exif数据的相机软件/设备制造商，因此它在大多数情况下都可以工作，但它不是100%可靠的解决方案。
ExifInterface ei = new ExifInterface(photoPath);
int orientation = ei.getAttributeInt(ExifInterface.TAG_ORIENTATION,
ExifInterface.ORIENTATION_UNDEFINED);
Bitmap rotatedBitmap = null;
switch(orientation) {
case ExifInterface.ORIENTATION_ROTATE_90:
rotatedBitmap = rotateImage(bitmap, 90);
break;
case ExifInterface.ORIENTATION_ROTATE_180:
rotatedBitmap = rotateImage(bitmap, 180);
break;
case ExifInterface.ORIENTATION_ROTATE_270:
rotatedBitmap = rotateImage(bitmap, 270);
break;
case ExifInterface.ORIENTATION_NORMAL:
default:
rotatedBitmap = bitmap;
}
下面是rotateImage方法:
public static Bitmap rotateImage(Bitmap source, float angle) {
Matrix matrix = new Matrix();
matrix.postRotate(angle);
return Bitmap.createBitmap(source, 0, 0, source.getWidth(), source.getHeight(),
matrix, true);
}
我根据@Jason Robinson的回答创建了一个Kotlin扩展函数，简化了Kotlin开发人员的操作。我希望这能有所帮助。
fun Bitmap.fixRotation(uri: Uri): Bitmap? {
val ei = ExifInterface(uri.path)
val orientation: Int = ei.getAttributeInt(
ExifInterface.TAG_ORIENTATION,
ExifInterface.ORIENTATION_UNDEFINED
)
return when (orientation) {
ExifInterface.ORIENTATION_ROTATE_90 -> rotateImage( 90f)
ExifInterface.ORIENTATION_ROTATE_180 -> rotateImage( 180f)
ExifInterface.ORIENTATION_ROTATE_270 -> rotateImage( 270f)
ExifInterface.ORIENTATION_NORMAL -> this
else -> this
}
}
fun Bitmap.rotateImage(angle: Float): Bitmap? {
val matrix = Matrix()
matrix.postRotate(angle)
return Bitmap.createBitmap(
this, 0, 0, width, height,
matrix, true
)
}
Jason Robinson和Sami Eltamawy的回答非常棒。
只是为了完成该方法的改进，您应该使用compat ExifInterface。
com.android.support: exifinterface: $ {lastLibVersion}
你将能够实例化ExifInterface(pior API <24)与InputStream(从ContentResolver)而不是uri路径避免“文件未找到异常”
https://android-developers.googleblog.com/2016/12/introducing-the-exifinterface-support-library.html
