Implemented being robust to configuration change;

raheemadamboev · Feb 26, 2023 · f0c4894 · f0c4894
1 parent 6573ca6
commit f0c4894
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Showing 3 changed files with 37 additions and 4 deletions.
diff --git a/app/src/main/java/xyz/teamgravity/pinlockcomposedemo/MainActivity.kt b/app/src/main/java/xyz/teamgravity/pinlockcomposedemo/MainActivity.kt
@@ -12,6 +12,7 @@ import androidx.compose.material3.Text
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
@@ -37,7 +38,7 @@ class MainActivity : ComponentActivity() {
                     modifier = Modifier.fillMaxSize(),
                     color = MaterialTheme.colorScheme.background
                 ) {
-                    var navigation by remember { mutableStateOf(Screen.Authenticate) }
+                    var navigation by rememberSaveable { mutableStateOf(Screen.Authenticate) }
 
                     when (navigation) {
                         Screen.Authenticate -> {

diff --git a/pin_lock_compose/src/main/java/xyz/teamgravity/pin_lock_compose/PinLock.kt b/pin_lock_compose/src/main/java/xyz/teamgravity/pin_lock_compose/PinLock.kt
@@ -12,6 +12,7 @@ import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.material3.*
 import androidx.compose.runtime.*
+import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
@@ -46,7 +47,7 @@ fun PinLock(
 ) {
     var animate by remember { mutableStateOf(false) }
 
-    val numbers = remember { mutableStateListOf<Int>() }
+    val numbers = rememberMutableStateListOf<Int>()
     val pinExists = remember { PinManager.pinExists() }
 
     BasePinLock(
@@ -106,10 +107,10 @@ fun ChangePinLock(
     onPinIncorrect: () -> Unit,
     onPinChanged: () -> Unit,
 ) {
-    var authenticated by remember { mutableStateOf(false) }
+    var authenticated by rememberSaveable { mutableStateOf(false) }
     var animate by remember { mutableStateOf(false) }
 
-    val numbers = remember { mutableStateListOf<Int>() }
+    val numbers = rememberMutableStateListOf<Int>()
 
     BasePinLock(
         title = {

diff --git a/...lock_compose/src/main/java/xyz/teamgravity/pin_lock_compose/rememberMutableStateListOf.kt b/...lock_compose/src/main/java/xyz/teamgravity/pin_lock_compose/rememberMutableStateListOf.kt
@@ -0,0 +1,31 @@
+package xyz.teamgravity.pin_lock_compose
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.saveable.listSaver
+import androidx.compose.runtime.saveable.rememberSaveable
+import androidx.compose.runtime.snapshots.SnapshotStateList
+import androidx.compose.runtime.toMutableStateList
+
+/**
+ * It behaves similarly to remember, but the stored value will survive the activity or process recreation using the saved instance
+ * state mechanism (for example it happens when the screen is rotated in the Android application).
+ */
+@Composable
+internal fun <T : Any> rememberMutableStateListOf(vararg elements: T): SnapshotStateList<T> {
+    return rememberSaveable(
+        saver = listSaver(
+            save = { stateList ->
+                if (stateList.isNotEmpty()) {
+                    val first = stateList.first()
+                    if (!canBeSaved(first)) {
+                        throw IllegalStateException("${first::class} cannot be saved. By default only types which can be stored in the Bundle class can be saved.")
+                    }
+                }
+                stateList.toList()
+            },
+            restore = { it.toMutableStateList() }
+        )
+    ) {
+        elements.toList().toMutableStateList()
+    }
+}