task(SDK-4506) - Moves renderNotification to an executor thread (#304)

* task(SDK-4506) - Moves renderNotification to an executor thread
- The core SDK API expected to be called only on a worker thread
- This ensures the images are downloaded correctly

* task(SDK-4506) - Resolves PR comments

* task(SDK-4506) - Adds changelog and bumps versions

Author: Anush-Shand

CHANGELOG.md

@@ -8,6 +8,9 @@ Version 3.3.1 *(18 April 2025)*
   * Adds `dismissInAppNotification` action to dismiss custom HTML in-Apps
 
 **Bug Fixes**
+* **[Android Platform]**
+* Fixes an issue where images failed to render in push templates when using a custom FCM integration.
+
 * **[iOS Platform]**
   * Fixes app freezing issue when using await with `defineVariables()`.
   * Fixes custom in-app device orientation check.

android/build.gradle

@@ -1,5 +1,5 @@
 group = 'com.clevertap.clevertap_plugin'
-version = '3.3.0'
+version = '3.3.1'
 
 buildscript {
     ext.kotlin_version = "1.8.22"

android/src/main/java/com/clevertap/clevertap_plugin/DartToNativePlatformCommunicator.kt

@@ -4,6 +4,7 @@ import android.annotation.SuppressLint
 import android.content.Context
 import android.location.Location
 import android.os.Build
+import android.os.Looper
 import android.util.Log
 import com.clevertap.android.sdk.CleverTapAPI
 import com.clevertap.android.sdk.UTMDetail
@@ -24,13 +25,16 @@ import io.flutter.plugin.common.MethodChannel
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler
 import org.json.JSONException
 import org.json.JSONObject
+import java.util.concurrent.Executors
 
 @Suppress("DEPRECATION")
 class DartToNativePlatformCommunicator(
     private val context: Context,
     private val cleverTapAPI: CleverTapAPI?
 ) : MethodCallHandler {
 
+    private val notificationExecutor = Executors.newSingleThreadExecutor()
+
     companion object {
         const val TAG = "DartToNative"
 
@@ -990,29 +994,40 @@ class DartToNativePlatformCommunicator(
      */
     private fun renderNotification(call: MethodCall, result: MethodChannel.Result) {
         val extras = call.argument<String>("extras")
-        if (cleverTapAPI != null) {
-            val isSuccess: Boolean
-            try {
-                Log.d(TAG, "renderNotification Android")
-                val messageBundle = Utils.stringToBundle(extras)
-                isSuccess = PushNotificationHandler.getPushNotificationHandler()
-                    .onMessageReceived(context, messageBundle, PushConstants.FCM.type)
-                if (isSuccess) {
-                    result.success(null)
-                } else {
-                    throw java.lang.Exception("Unable to process notification rendering")
+        if (cleverTapAPI == null) {
+            result.error(TAG, ERROR_MSG, null)
+        }
+        try {
+            Log.d(TAG, "renderNotification Android")
+            // Check if we're on the main thread. Needed since plugins like FCM provide on message received on the main thread
+            if (Looper.myLooper() == Looper.getMainLooper()) {
+                // We're on the main thread, execute on a background thread
+                notificationExecutor.execute {
+                    processNotification(extras, result)
                 }
-            } catch (e: JSONException) {
-                result.error(
-                    TAG,
-                    "Unable to render notification due to JSONException - " + e.localizedMessage,
-                    null
-                )
-            } catch (e: java.lang.Exception) {
-                result.error(TAG, e.localizedMessage, null)
+            } else {
+                processNotification(extras, result)
             }
+        } catch (e: JSONException) {
+            result.error(
+                TAG,
+                "Unable to render notification due to JSONException - " + e.localizedMessage,
+                null
+            )
+        } catch (e: Exception) {
+            result.error(TAG, e.localizedMessage, null)
+        }
+    }
+
+    private fun processNotification(extras: String?, result: MethodChannel.Result) {
+        val messageBundle = Utils.stringToBundle(extras)
+        val isSuccess = PushNotificationHandler.getPushNotificationHandler()
+            .onMessageReceived(context, messageBundle, PushConstants.FCM.type)
+
+        if (isSuccess) {
+            result.success(null)
         } else {
-            result.error(TAG, ERROR_MSG, null)
+            result.error(TAG, "Unable to process notification rendering", null)
         }
     }