wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/QRCodeComposable.kt


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package ch.bfh.habej2.wallee_c2ec

import android.graphics.Bitmap
import android.graphics.Color
import androidx.compose.foundation.Image
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.runtime.Composable
import androidx.compose.ui.graphics.asImageBitmap
import androidx.compose.ui.platform.LocalConfiguration
import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.min
import com.google.zxing.BarcodeFormat.QR_CODE
import com.google.zxing.qrcode.QRCodeWriter

@Composable
fun QRCode(qrCodeContent: String) {

    Column {

        val qrCodeSize = getQrCodeSize()
        val btmp = makeQrCode(qrCodeContent).asImageBitmap()

        Image(
            modifier = androidx.compose.ui.Modifier
                .size(qrCodeSize)
                .padding(vertical = 8.dp),
            bitmap = btmp,
            contentDescription = "Scan the QR Code to start withdrawal",
        )
    }
}

@Composable
fun getQrCodeSize(): Dp {
    val configuration = LocalConfiguration.current
    val screenHeight = configuration.screenHeightDp.dp
    val screenWidth = configuration.screenWidthDp.dp
    return min(screenHeight, screenWidth)
}

private fun makeQrCode(text: String, size: Int = 256): Bitmap {
    val qrCodeWriter = QRCodeWriter()
    val bitMatrix = qrCodeWriter.encode(text, QR_CODE, size, size)
    val height = bitMatrix.height
    val width = bitMatrix.width
    val bmp = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565)
    for (x in 0 until width) {
        for (y in 0 until height) {
            bmp.setPixel(x, y, if (bitMatrix.get(x, y)) Color.BLACK else Color.WHITE)
        }
    }
    return bmp
}