iOS Question pictures is rotated withouth reason

[omarruben]

Hi guys, I am using low lever camera lib and is working excelent, I am saving the file wiht next code:

Dim Out As OutputStream
Out = File.OpenOutput(XUI.DefaultFolder, "Test.png", False)
Bitmap1.WriteToStream(out, 100, "PNG")
Out.Close

no problem....
but when reading the file back and put on a BMP the image is rotated

Dim bmp As B4XBitmap = LoadBitmapResize(File.DirDocuments, "Test.png", 150dip, 150dip, True)
ImageView.Bitmap = bmp

can anyone explain what I am doing wrong?
thank you

 

[Erel]

Tip: better to be consistent with XUI.DefaultFolder (which is the same as File.DirDocuments).

What happens if you try to show the image before it is saved (Bitmap1)?

 

[Magma]

...That seems like EXIF... setting by camera... viewer read that (landscape, portrait orientation)

 

[Erel]

EXIF is handled automatically in iOS. The loaded bitmap should be loaded with the correct orientation.

 

[Semen Matusovskiy]

When you take a photo, a bitmap has a correct orientation. But bmp.WriteToStream does not write 'orientation' tag in Exif.
I found three parameters only : ColorSpace, PixelXDimension, PixelYDimension). Means IOS will assume UIImageOrientationUp.

Workaround ...

1) Add to the bottom

#If OBJC
- (UIImage*) removeOrientation: (UIImage*) image { return [UIImage imageWithCGImage: [image CGImage] scale: [image scale] orientation: UIImageOrientationUp]; }
#End If

2) In PictureTaken after receiving a bitmap (let's name it bmp):
a) get image orientation

    Dim byteOrientation As Byte = bmp.As(NativeObject).GetField("imageOrientation").AsNumber

b) set image orientation to UIImageOrientationUp (means The original pixel data matches the image's intended display orientation).

    Dim no As NativeObject = Me
    bmp = no.RunMethod ("removeOrientation:", Array (bmp))

c) rotate a bitmap

    Select Case byteOrientation
        Case 0
            ' bmp = bmp.Rotate (0)
        Case 1
            bmp = bmp.Rotate (180)
        Case 2
             bmp = bmp.Rotate (270)
        Case 3
            bmp = bmp.Rotate (90)
    End Select

After this you can use bmp.WriteToStream.

 

[omarruben]

Tip: better to be consistent with XUI.DefaultFolder (which is the same as File.DirDocuments).

What happens if you try to show the image before it is saved (Bitmap1)?

shows normal no rotation... looks like using Bitmap1.WriteToStream(out, 100, "PNG") is rotated

 

[omarruben]

When you take a photo, a bitmap has a correct orientation. But bmp.WriteToStream does not write 'orientation' tag in Exif.
I found three parameters only : ColorSpace, PixelXDimension, PixelYDimension). Means IOS will assume UIImageOrientationUp.

Workaround ...

1) Add to the bottom

#If OBJC
- (UIImage*) removeOrientation: (UIImage*) image { return [UIImage imageWithCGImage: [image CGImage] scale: [image scale] orientation: UIImageOrientationUp]; }
#End If

2) In PictureTaken after receiving a bitmap (let's name it bmp):
a) get image orientation

    Dim byteOrientation As Byte = bmp.As(NativeObject).GetField("imageOrientation").AsNumber

b) set image orientation to UIImageOrientationUp (means The original pixel data matches the image's intended display orientation).

    Dim no As NativeObject = Me
    bmp = no.RunMethod ("removeOrientation:", Array (bmp))

c) rotate a bitmap

    Select Case byteOrientation
        Case 0
            ' bmp = bmp.Rotate (0)
        Case 1
            bmp = bmp.Rotate (180)
        Case 2
             bmp = bmp.Rotate (270)
        Case 3
            bmp = bmp.Rotate (90)
    End Select

After this you can use bmp.WriteToStream.

I will try today, thank you