Convert Composable To Bitmap Without Displaying It

compose-to-bitmap-tools.kt

@Composable
fun BitmapComposable(
    onBitmapped: (bitmap: Bitmap) -> Unit = { _ -> },
    backgroundColor: Color = Color.Transparent,
    dpSize : DpSize,
    readyToDraw : State<Boolean> = mutableStateOf(true),
    composable: @Composable () -> Unit
) {
    var lastBitmap : Bitmap? = remember {
        null
    }
    LaunchedEffect(key1 = readyToDraw.value, block = {
        Log.d("readyToDraw", "ready ! to draw")
        if (readyToDraw.value && lastBitmap != null) {
            onBitmapped(lastBitmap!!)
        }
    })
    Box(
        modifier = Modifier
        .size(0.dp, 0.dp)
        .verticalScroll(
            rememberScrollState(), enabled = false
        )
        .horizontalScroll(
            rememberScrollState(), enabled = false
        )
    ) {

        Box(modifier = Modifier.size(dpSize)) {
            AndroidView(factory = {
                ComposeView(it).apply {
                    setContent {
                        Box(modifier = Modifier
                            .background(backgroundColor)
                            .size(dpSize)) {
                            composable()
                        }
                    }
                }
            }, modifier = Modifier.fillMaxSize(), update = {
                it.run {
                    doOnLayout {
                        if (readyToDraw.value) {
                            lastBitmap = drawToBitmap()
                        }
                    }
                }
            })
        }
    }

}

@Composable
fun BitmapComposable(
    onBitmapped: (bitmap: Bitmap) -> Unit = { _ -> },
    backgroundColor: Color = Color.Transparent,
    intSize : IntSize = StudentCardSize,
    readyToDraw : State<Boolean> = mutableStateOf(true),
    composable: @Composable () -> Unit
) {
    val renderComposableSize = LocalDensity.current.run { intSize.toSize().toDpSize() }
    BitmapComposable(onBitmapped,backgroundColor,renderComposableSize,readyToDraw,composable)
}