GLFrontBufferedRenderer setup

GLFrontBufferedRenderer.kt

/* Copyright 2022 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
   
val callbacks = object : GLFrontBufferedRenderer.Callback<DATA_TYPE> {
    override fun onDrawFrontBufferedLayer(
        eglManager: EGLManager,
        bufferWidth: Int,
        bufferHeight: Int,
        transform: FloatArray,
        param: DATA_TYPE
    ) {
        // OpenGL work for Front buffer layer
    }

    override fun onDrawDoubleBufferedLayer(
        eglManager: EGLManager,
        bufferWidth: Int,
        bufferHeight: Int,
        transform: FloatArray,
        params: Collection<DATA_TYPE>
    ) {
        // OpenGL work for Doubled buffer layer
    }
}

val frontBufferRenderer = GLFrontBufferedRenderer(mySurfaceView, callbacks)

// Add a OnTouchListener, to get the motion data and send then  
// to frontBufferRenderer for rendering.
mySurfaceView.setOnTouchListener { v, event ->
            // MotionEvent to DATA_TYPE - function to implement yourself
            val dataPoint = event.toDATA_TYPE()
                
            when (event.action) {
                MotionEvent.ACTION_DOWN -> {
                    // Render a new data point directly to the front buffer layer
                    frontBufferRenderer.renderFrontBufferedLayer(dataPoint)
                }

                MotionEvent.ACTION_MOVE -> {
                    // Render a new data point directly to the front buffer layer
                    frontBufferRenderer.renderFrontBufferedLayer(dataPoint)
                }

                MotionEvent.ACTION_UP -> {
                    // Stroke is done, commit the data points to the double buffered layer
                    frontBufferRenderer.commit()
                }
                else -> Unit
            }
            true
        }