Face Landmarker centering logic

fragment_camera.xml

<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/camera_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.camera.view.PreviewView
        android:id="@+id/view_finder"
        android:layout_width="match_parent"
        android:layout_height="match_parent" // removed   app:scaleType="fillStart"                         
       />
   
    ....
</androidx.coordinatorlayout.widget.CoordinatorLayout>

OverlayView.kt

    override fun draw(canvas: Canvas) {
        super.draw(canvas)

        // Clear previous drawings if results exist but have no face landmarks
        if (results?.faceLandmarks().isNullOrEmpty()) {
            clear()
            return
        }

        results?.let { faceLandmarkerResult ->

            // Calculate scaled image dimensions
            val scaledImageWidth = imageWidth * scaleFactor
            val scaledImageHeight = imageHeight * scaleFactor

            // Calculate offsets to center the image on the canvas
            val offsetX = (width - scaledImageWidth) / 2f
            val offsetY = (height - scaledImageHeight) / 2f

            // Iterate through each detected face
            faceLandmarkerResult.faceLandmarks().forEach { faceLandmarks ->
                // Draw all landmarks for the current face
                drawFaceLandmarks(canvas, faceLandmarks, offsetX, offsetY)

                // Draw all connectors for the current face
                drawFaceConnectors(canvas, faceLandmarks, offsetX, offsetY)
            }
        }
    }

    /**
     * Draws all landmarks for a single face on the canvas.
     */
    private fun drawFaceLandmarks(
        canvas: Canvas,
        faceLandmarks: List<NormalizedLandmark>,
        offsetX: Float,
        offsetY: Float
    ) {
        faceLandmarks.forEach { landmark ->
            val x = landmark.x() * imageWidth * scaleFactor + offsetX
            val y = landmark.y() * imageHeight * scaleFactor + offsetY
            canvas.drawPoint(x, y, pointPaint)
        }
    }

    /**
     * Draws all connectors between landmarks for a single face on the canvas.
     */
    private fun drawFaceConnectors(
        canvas: Canvas,
        faceLandmarks: List<NormalizedLandmark>,
        offsetX: Float,
        offsetY: Float
    ) {
        FaceLandmarker.FACE_LANDMARKS_CONNECTORS.filterNotNull().forEach { connector ->
            val startLandmark = faceLandmarks.getOrNull(connector.start())
            val endLandmark = faceLandmarks.getOrNull(connector.end())

            if (startLandmark != null && endLandmark != null) {
                val startX = startLandmark.x() * imageWidth * scaleFactor + offsetX
                val startY = startLandmark.y() * imageHeight * scaleFactor + offsetY
                val endX = endLandmark.x() * imageWidth * scaleFactor + offsetX
                val endY = endLandmark.y() * imageHeight * scaleFactor + offsetY

                canvas.drawLine(startX, startY, endX, endY, linePaint)
            }
        }
    }