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  1. Qt
  2. QTBUG-85550

Invalid rotation being set for camera on android devices

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    Details

    • Type: Bug
    • Status: Reported
    • Priority: P2: Important
    • Resolution: Unresolved
    • Affects Version/s: 5.14.2
    • Fix Version/s: None
    • Component/s: Multimedia
    • Labels:
      None
    • Platform/s:
      Android

      Description

      Code for camera imageCapture on android sets rotation of camera based on orientation sensor, instead of using data on how android UI is orientated while creating a photo.


       

      The rotation which a camera uses on android is being calculated in

      src/qtmultimedia/src/plugins/android/src/mediacapture/qandroidcamerasession.cpp

      in

      int QAndroidCameraSession::currentCameraRotation() const

      as

       

      // subtract natural camera orientation and physical device orientation
       int rotation = 0;
       int deviceOrientation = (AndroidMultimediaUtils::getDeviceOrientation() + 45) / 90 * 90;
       if (m_camera->getFacing() == AndroidCamera::CameraFacingFront)
       rotation = (m_nativeOrientation - deviceOrientation + 360) % 360;
       else // back-facing camera
       rotation = (m_nativeOrientation + deviceOrientation) % 360;
      

       

      and this value is passed to native cameraRotation ( https://developer.android.com/reference/android/hardware/Camera.Parameters#setRotation(int) ) whenever image is being capture in method

       

      int QAndroidCameraSession::capture(const QString &fileName)

      as

       

      // adjust picture rotation depending on the device orientation
       m_camera->setRotation(currentCameraRotation());

       

      So in many cases, when device is at 45 degrees, in position just UI to be re-orientated e.g. from portrait to landscape, camera will rotate result as if a device was already in landscape, while UI is still in portrait.

      This happens a lot e.g. if you take device with UI in portrait-orientation, and try to photo some text, placing a device horizontally to a table's surface, while slighly tilting it into landscape, but not fully enough for UI to go to landscape. In result you get imageCapture with wrong rotation.


       

      As of now the only way-out to determine correct orientation of result photo: redo all steps are being done inside QAndroidCameraSession::currentCameraRotation(), get rotation used by camera, compare it to rotation of UI when taking a photo, and if they differ: rotate captured image to needed angle.

      The correct behaviour of imageCapture would be to use UI's orientation's, instead of sensor's.

       

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            People

            Assignee:
            valentyn.doroshchuk Valentyn Doroshchuk
            Reporter:
            savthegood Alex So
            Votes:
            1 Vote for this issue
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              Dates

              Created:
              Updated:

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