Jetpack Compose设置通知大图标出现类型不匹配错误如何解决

错误原因 #

NotificationCompat.Builder的setLargeIcon()方法要求传入Bitmap类型的实例，你直接传了R.drawable.header，这是Android系统生成的drawable资源唯一标识，属于Int类型，所以触发类型不匹配报错。

修复方案 #

你需要先把drawable资源转换为Bitmap对象，再传入setLargeIcon()方法，针对你使用png格式图片的场景，直接用系统自带的BitmapFactory解码资源即可：

@Composable
fun NotificationApp() {
    val context = LocalContext.current
    val channelId = "MyTestChannel"
    val notificationId = 0

    // 新增：将drawable资源转换为Bitmap
    val largeIcon = BitmapFactory.decodeResource(context.resources, R.drawable.header)

    val builder = NotificationCompat.Builder(context, channelId)
        .setSmallIcon(R.drawable.ic_edit_location) 
        .setContentTitle("My Test Notification")
        .setContentText("This is my test notification in one line...")
        .setLargeIcon(largeIcon) // 替换为转换后的Bitmap对象
        .setStyle(
            NotificationCompat.BigTextStyle()
                .bigText(
                    "This is my test notification in one line. Made it longer " +
                            "by setting the setStyle property. " +
                            "It should not fit in one line anymore, " +
                            "rather show as a longer notification content."
                )
        )
        .setPriority(NotificationCompat.PRIORITY_DEFAULT)

    createNotificationChannel(channelId, context)

    with(NotificationManagerCompat.from(context)) {
        notify(notificationId, builder.build())
    }
}

如果你后续需要使用矢量图作为大图标，可以使用下面的通用转换方法处理：

fun drawableToBitmap(drawable: Drawable): Bitmap {
    if (drawable is BitmapDrawable) {
        return drawable.bitmap
    }
    val bitmap = Bitmap.createBitmap(drawable.intrinsicWidth, drawable.intrinsicHeight, Bitmap.Config.ARGB_8888)
    val canvas = Canvas(bitmap)
    drawable.setBounds(0, 0, canvas.width, canvas.height)
    drawable.draw(canvas)
    return bitmap
}

调用方式如下：

val drawable = ContextCompat.getDrawable(context, R.drawable.header) ?: return
val largeIcon = drawableToBitmap(drawable)

内容的提问来源于stack exchange，提问作者Raw Hasan