Add screen capture protection (#292)

Co-authored-by: Rahul Sharma <rahul.shwork@gmail.com>

app/src/main/java/com/aryan/reader/AppUiModels.kt

@@ -124,4 +124,5 @@ data class ReaderScreenState(
     val customAppThemes: List<CustomAppTheme> = emptyList(),
     val allTags: List<TagEntity> = emptyList(),
     val showTagSelectionDialogFor: Set<String> = emptySet(),
+    val isScreenCaptureProtectionEnabled: Boolean = false,
 )

app/src/main/java/com/aryan/reader/HomeScreen.kt

@@ -359,6 +359,15 @@ fun HomeScreen(
                                 onExportLogsClick = { viewModel.exportLogsToFile(context) },
                                 onToggleHideReaderAi = {
                                     saveHideReaderAiFeatures(context, !loadHideReaderAiFeatures(context))
+                                },
+                                onScreenCaptureProtectionChange = { enabled ->
+                                    viewModel.setScreenCaptureProtectionEnabled(enabled)
+                                    val messageRes = if (enabled) {
+                                        R.string.banner_screen_capture_protection_on
+                                    } else {
+                                        R.string.banner_screen_capture_protection_off
+                                    }
+                                    viewModel.showBanner(context.getString(messageRes))
                                 }
                             )
                         } else {
@@ -1019,7 +1028,8 @@ fun DefaultTopAppBar(
     onTestSpeechBubbleDetectionClick: () -> Unit,
     onLanguageClick: () -> Unit,
     onExportLogsClick: () -> Unit,
-    onToggleHideReaderAi: () -> Unit
+    onToggleHideReaderAi: () -> Unit,
+    onScreenCaptureProtectionChange: (Boolean) -> Unit
 ) {
     var showOptionsMenu by remember { mutableStateOf(false) }
     var showLimitMenu by remember { mutableStateOf(false) }
@@ -1090,6 +1100,19 @@ fun DefaultTopAppBar(
                     }
                 })
 
+                DropdownMenuItem(
+                    text = { Text(stringResource(R.string.options_screen_capture_protection)) },
+                    onClick = {
+                        onScreenCaptureProtectionChange(!uiState.isScreenCaptureProtectionEnabled)
+                        showOptionsMenu = false
+                    },
+                    trailingIcon = {
+                        if (uiState.isScreenCaptureProtectionEnabled) {
+                            Icon(Icons.Default.Check, contentDescription = stringResource(R.string.content_desc_enabled))
+                        }
+                    }
+                )
+
                 DropdownMenuItem(text = { Text(stringResource(R.string.options_external_file_behavior)) }, onClick = {
                     onExternalFileBehaviorClick()
                     showOptionsMenu = false

app/src/main/java/com/aryan/reader/MainActivity.kt

@@ -22,6 +22,7 @@ package com.aryan.reader
 import android.content.Intent
 import android.os.Build
 import android.os.Bundle
+import android.view.WindowManager
 import android.webkit.WebView
 import androidx.appcompat.app.AppCompatActivity
 import androidx.activity.compose.setContent
@@ -34,6 +35,8 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
 import androidx.compose.material3.windowsizeclass.ExperimentalMaterial3WindowSizeClassApi
 import androidx.compose.material3.windowsizeclass.calculateWindowSizeClass
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
 import androidx.compose.ui.Modifier
 import androidx.lifecycle.lifecycleScope
 import androidx.navigation.compose.rememberNavController
@@ -87,6 +90,8 @@ class MainActivity : AppCompatActivity() {
         setContent {
             val uiState by viewModel.uiState.collectAsStateWithLifecycle()
 
+            ScreenCaptureProtectionEffect(enabled = uiState.isScreenCaptureProtectionEnabled)
+
             val darkTheme = when (uiState.appThemeMode) {
                 AppThemeMode.LIGHT -> false
                 AppThemeMode.DARK -> true
@@ -131,4 +136,21 @@ class MainActivity : AppCompatActivity() {
             viewModel.onFileSelected(uri, isFromRecent = false, isExternalIntent = true)
         }
     }
-}
+}
+
+@Composable
+private fun MainActivity.ScreenCaptureProtectionEffect(enabled: Boolean) {
+    DisposableEffect(enabled) {
+        if (enabled) {
+            window.addFlags(WindowManager.LayoutParams.FLAG_SECURE)
+        } else {
+            window.clearFlags(WindowManager.LayoutParams.FLAG_SECURE)
+        }
+
+        onDispose {
+            if (enabled) {
+                window.clearFlags(WindowManager.LayoutParams.FLAG_SECURE)
+            }
+        }
+    }
+}

app/src/main/java/com/aryan/reader/MainViewModel.kt

@@ -544,6 +544,7 @@ open class MainViewModel(application: Application) : AndroidViewModel(applicatio
             activeTabBookId = prefs.getString(KEY_ACTIVE_TAB, null),
             externalFileBehavior = prefs.getString(KEY_EXTERNAL_FILE_BEHAVIOR, "ASK") ?: "ASK",
             useStrictFileFilter = prefs.getBoolean(KEY_USE_STRICT_FILE_FILTER, false),
+            isScreenCaptureProtectionEnabled = prefs.getBoolean(KEY_SCREEN_CAPTURE_PROTECTION, false),
             appThemeMode = try {
                 AppThemeMode.valueOf(prefs.getString(KEY_APP_THEME_MODE, AppThemeMode.SYSTEM.name) ?: AppThemeMode.SYSTEM.name)
             } catch (_: Exception) { AppThemeMode.SYSTEM },
@@ -5227,6 +5228,11 @@ open class MainViewModel(application: Application) : AndroidViewModel(applicatio
         _internalState.update { it.copy(useStrictFileFilter = enabled) }
     }
 
+    fun setScreenCaptureProtectionEnabled(enabled: Boolean) {
+        prefs.edit { putBoolean(KEY_SCREEN_CAPTURE_PROTECTION, enabled) }
+        _internalState.update { it.copy(isScreenCaptureProtectionEnabled = enabled) }
+    }
+
     private fun loadCustomAppThemes(prefs: SharedPreferences): List<CustomAppTheme> {
         val jsonString = prefs.getString(KEY_CUSTOM_APP_THEMES, "[]") ?: "[]"
         val themes = mutableListOf<CustomAppTheme>()
@@ -5506,6 +5512,7 @@ open class MainViewModel(application: Application) : AndroidViewModel(applicatio
         private const val KEY_LAST_OPEN_FILE_TYPE = "last_open_file_type"
         private const val KEY_EXTERNAL_FILE_BEHAVIOR = "external_file_behavior"
         private const val KEY_USE_STRICT_FILE_FILTER = "use_strict_file_filter"
+        private const val KEY_SCREEN_CAPTURE_PROTECTION = "screen_capture_protection_enabled"
         private const val KEY_APP_THEME_MODE = "app_theme_mode"
         private const val KEY_APP_CONTRAST_OPTION = "app_contrast_option"
         private const val KEY_APP_SEED_COLOR = "app_seed_color"

app/src/main/res/values/strings.xml

@@ -1304,4 +1304,7 @@
     <string name="action_exit_smart_zoom">Exit Smart Zoom</string>
     <string name="action_smart_comic_zoom">Smart Comic Zoom</string>
     <string name="desc_toggle_smart_comic_zoom">Toggle Smart Comic Zoom</string>
+    <string name="options_screen_capture_protection">Screen capture protection</string>
+    <string name="banner_screen_capture_protection_on">Screen capture protection is on</string>
+    <string name="banner_screen_capture_protection_off">Screen capture protection is off</string>
 </resources>

app/src/test/java/com/aryan/reader/MainViewModelTest.kt

@@ -319,6 +319,25 @@ class MainViewModelTest {
         verify { mockEditor.putString("external_file_behavior", "KEEP") }
     }
 
+    @Test
+    fun `screen capture protection persists and updates state`() = runTest {
+        backgroundScope.launch(UnconfinedTestDispatcher(testScheduler)) {
+            viewModel.uiState.collect {}
+        }
+
+        viewModel.setScreenCaptureProtectionEnabled(true)
+
+        val enabledState = viewModel.uiState.first { it.isScreenCaptureProtectionEnabled }
+        assertTrue(enabledState.isScreenCaptureProtectionEnabled)
+        verify { mockEditor.putBoolean("screen_capture_protection_enabled", true) }
+
+        viewModel.setScreenCaptureProtectionEnabled(false)
+
+        val disabledState = viewModel.uiState.first { !it.isScreenCaptureProtectionEnabled }
+        assertFalse(disabledState.isScreenCaptureProtectionEnabled)
+        verify { mockEditor.putBoolean("screen_capture_protection_enabled", false) }
+    }
+
     @Test
     fun `setSortOrder persists preference and reorders visible home and library lists`() = runTest {
         backgroundScope.launch(UnconfinedTestDispatcher(testScheduler)) {