[#109] Handle potential init exceptions and fallback

README.md

@@ -86,3 +86,12 @@ class MainActivity : ComponentActivity() {
     }
 }
 ```
+
+## Error handling and Fallback UI
+
+The `PayButton` composable wraps the underlying `PayButton` Android View, which may encounter errors during initialization. To handle these situations, the `PayButton` composable provides:
+
+*   **`onError` Callback:** Invoked when an error occurs during the button's initialization. This callback receives the `Throwable` that caused the error, allowing you to log it or take other actions.
+*   **`fallbackUi` Composable:** An optional composable function that is displayed in place of the button if an error occurs. If not provided, nothing will be displayed in case of error.
+
+This mechanism ensures that your app can gracefully handle potential issues with the `PayButton` and provide a fallback experience to the user.

app/src/main/java/com/example/composepaybutton/MainActivity.kt

@@ -24,6 +24,7 @@ import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.width
+import androidx.compose.material.Button
 import androidx.compose.material.Divider
 import androidx.compose.material.Text
 import androidx.compose.ui.Alignment
@@ -103,6 +104,12 @@ class MainActivity : ComponentActivity() {
                     // Disabled buttons
                     PayButton(onClick = onClick, allowedPaymentMethods = allowedPaymentMethods, type = ButtonType.Checkout, enabled = false)
                     PayButton(onClick = onClick, allowedPaymentMethods = allowedPaymentMethods, type = ButtonType.Checkout, theme = ButtonTheme.Light, enabled = false)
+
+                    Divider(thickness = 1.dp, color = Color.LightGray)
+                    Text("Fallback UI")
+
+                    // Fallback UI in case of init failure
+                    PayButton(onClick = onClick, allowedPaymentMethods = allowedPaymentMethods, onError = { println("Error: $it") }) { Button(onClick = onClick) { Text("Fallback UI") }}
                 }
             }
         }

compose-pay-button/src/main/java/com/google/pay/button/PayButton.kt

@@ -17,15 +17,18 @@
 package com.google.pay.button
 
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.viewinterop.AndroidView
-
+import com.google.android.gms.wallet.button.ButtonConstants
 import com.google.android.gms.wallet.button.ButtonOptions
 import com.google.android.gms.wallet.button.PayButton as GmsPayButton
-import com.google.android.gms.wallet.button.ButtonConstants
 
 enum class ButtonTheme(val value: Int) {
     Dark(ButtonConstants.ButtonTheme.DARK),
@@ -55,35 +58,50 @@ fun PayButton(
     type: ButtonType = ButtonType.Buy,
     radius: Dp = 100.dp,
     enabled: Boolean = true,
+    onError: (Throwable) -> Unit = {},
+    fallbackUi: @Composable (() -> Unit)? = null,
 ) {
 
+    var showFallback by remember { mutableStateOf(false) }
+
     val radiusPixelValue = with(LocalDensity.current) { radius.toPx().toInt() }
 
-    AndroidView(
-        modifier = modifier,
-        factory = { context ->
-            GmsPayButton(context).apply {
-                this.initialize(
-                    ButtonOptions.newBuilder()
-                        .setButtonTheme(theme.value)
-                        .setButtonType(type.value)
-                        .setCornerRadius(radiusPixelValue)
-                        .setAllowedPaymentMethods(allowedPaymentMethods)
-                        .build()
-                )
-            }
-        },
-        update = { button ->
-            button.apply {
-                alpha = if (enabled) FULL_ALPHA else HALF_ALPHA
-                isEnabled = enabled
+    if (!showFallback) {
+        AndroidView(
+            modifier = modifier,
+            factory = { context ->
+                GmsPayButton(context).apply {
+                    kotlin.runCatching {
+                        this.initialize(
+                            ButtonOptions.newBuilder()
+                                .setButtonTheme(theme.value)
+                                .setButtonType(type.value)
+                                .setCornerRadius(radiusPixelValue)
+                                .setAllowedPaymentMethods(allowedPaymentMethods)
+                                .build()
+                        )
+                    }.onFailure {
+                        onError(it)
+                        showFallback = true
+                    }
+                }
+            },
+            update = { button ->
+                if (!showFallback) {
+                    button.apply {
+                        alpha = if (enabled) FULL_ALPHA else HALF_ALPHA
+                        isEnabled = enabled
 
-                if (enabled) {
-                    setOnClickListener { onClick() }
-                } else {
-                    setOnClickListener(null)
+                        if (enabled) {
+                            setOnClickListener { onClick() }
+                        } else {
+                            setOnClickListener(null)
+                        }
+                    }
                 }
             }
-        }
-    )
-}
+        )
+    } else {
+        fallbackUi?.invoke()
+    }
+}