camerax_pinch_to_zoom.kt

// Listen to pinch gestures
val listener = object : ScaleGestureDetector.SimpleOnScaleGestureListener() {
    override fun onScale(detector: ScaleGestureDetector): Boolean {
        // Get the camera's current zoom ratio
        val currentZoomRatio = cameraInfo.zoomState.value?.zoomRatio ?: 0F
        
        // Get the pinch gesture's scaling factor 
        val delta = detector.scaleFactor
        
        // Update the camera's zoom ratio. This is an asynchronous operation that returns
        // a ListenableFuture, allowing you to listen to when the operation completes.
        cameraControl.setZoomRatio(currentZoomRatio * delta)
        
        // Return true, as the event was handled
        return true
    }
}
val scaleGestureDetector = ScaleGestureDetector(context, listener)

// Attach the pinch gesture listener to the viewfinder
previewView.setOnTouchListener { _, event ->
    scaleGestureDetector.onTouchEvent(event)
    return@setOnTouchListener true
}

cant find zoomRatio
def camerax_version = "1.0.0-alpha05"
implementation "androidx.camera:camera-core:${camerax_version}"
implementation "androidx.camera:camera-camera2:${camerax_version}"

using this as per codelab

cant find zoomRatio
def camerax_version = "1.0.0-alpha05"
implementation "androidx.camera:camera-core:${camerax_version}"
implementation "androidx.camera:camera-camera2:${camerax_version}"

using this as per codelab

use like this.
camera?.cameraInfo?.zoomState?.value?.zoomRatio

As it is mentioned in the source comments the method

cameraControl.setZoomRatio(currentZoomRatio * delta)

seems to by asnc, so in case of multiple "onScale" events in a short period of time, the value read from

cameraInfo.zoomState.value?.zoomRatio

might not yet have been updated. In my case this leads to the zoom jumping back and forth during pinching.

Is there any way to work around this?

i found this error, can you help me ?

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
at android.view.ScaleGestureDetector.(ScaleGestureDetector.java:237)
at android.view.ScaleGestureDetector.(ScaleGestureDetector.java:217)
at id.t_rec.app.modules.absentx.AbsentXActivity.startCamera(AbsentXActivity.kt:126)