SurfaceScope

import androidx.compose.foundation.AndroidExternalSurface
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.runtime.withFrameNanos
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.lerp
import androidx.compose.ui.graphics.toArgb
import androidx.compose.ui.unit.dp

AndroidExternalSurface(modifier = Modifier.fillMaxWidth().height(400.dp)) {
    // Resources can be initialized/cached here

    // A surface is available, we can start rendering
    onSurface { surface, width, height ->
        var w = width
        var h = height

        // Initial draw to avoid a black frame
        surface.lockCanvas(Rect(0, 0, w, h)).apply {
            drawColor(Color.Blue.toArgb())
            surface.unlockCanvasAndPost(this)
        }

        // React to surface dimension changes
        surface.onChanged { newWidth, newHeight ->
            w = newWidth
            h = newHeight
        }

        // Cleanup if needed
        surface.onDestroyed {}

        // Render loop, automatically cancelled on surface destruction
        while (true) {
            withFrameNanos { time ->
                surface.lockCanvas(Rect(0, 0, w, h)).apply {
                    val timeMs = time / 1_000_000L
                    val t = 0.5f + 0.5f * sin(timeMs / 1_000.0f)
                    drawColor(lerp(Color.Blue, Color.Green, t).toArgb())
                    surface.unlockCanvasAndPost(this)
                }
            }
        }
    }
}