Add Enable/Disable functionality to Android

src/android/PrivacyScreenPlugin.java

@@ -12,6 +12,9 @@
 import org.apache.cordova.CordovaWebView;
 
 import android.app.Activity;
+import android.content.SharedPreferences;
+import android.preference.PreferenceManager;
+import android.util.Log;
 import android.view.Window;
 import android.view.WindowManager;
 
@@ -24,14 +27,114 @@
 
 /**
  * This class sets the FLAG_SECURE flag on the window to make the app
- *  private when shown in the task switcher
+ * private when shown in the task switcher
  */
 public class PrivacyScreenPlugin extends CordovaPlugin {
+  public static final String KEY_PRIVACY_SCREEN_ENABLED = "org.devgeeks.privacyscreen/PrivacyScreenEnabled";
+  private SharedPreferences preferences;
 
   @Override
   public void initialize(CordovaInterface cordova, CordovaWebView webView) {
     super.initialize(cordova, webView);
     Activity activity = this.cordova.getActivity();
-    activity.getWindow().addFlags(WindowManager.LayoutParams.FLAG_SECURE);
+    preferences = PreferenceManager.getDefaultSharedPreferences(activity);
+    boolean privacyScreenEnabled = isPrivacyScreenEnabled(true);
+
+    if (privacyScreenEnabled) {
+      activity.getWindow().addFlags(WindowManager.LayoutParams.FLAG_SECURE);
+    }
+  }
+
+  /**
+   * Gets the value of the Privacy Screen Enabled entry stored in {@link SharedPreferences}.
+   * Will not attempt to correct an erroneous entry.
+   *
+   * @param defValue The default value of the preference if not readable or non-existent.
+   * @return Whether the privacy screen should be enabled during the next application launch.
+   * @see #KEY_PRIVACY_SCREEN_ENABLED
+   * @see #isPrivacyScreenEnabled(boolean, boolean)
+   */
+  private boolean isPrivacyScreenEnabled(boolean defValue) {
+    return isPrivacyScreenEnabled(defValue, false);
+  }
+
+  /**
+   * Gets the value of the Privacy Screen Enabled entry stored in {@link SharedPreferences}.
+   *
+   * @param defValue      The default value of the preference if not readable or non-existent.
+   * @param shouldCorrect If true, will attempt to convert String value to Boolean or replace with the default value.
+   * @return Whether the privacy screen should be enabled during the next application launch.
+   * @see #KEY_PRIVACY_SCREEN_ENABLED
+   */
+  private boolean isPrivacyScreenEnabled(boolean defValue, boolean shouldCorrect) {
+    if (!preferences.contains(KEY_PRIVACY_SCREEN_ENABLED)) {
+      setPrivacyScreenEnabled(defValue);
+      return defValue;
+    }
+    try {
+      return preferences.getBoolean(KEY_PRIVACY_SCREEN_ENABLED, defValue);
+    } catch (ClassCastException e) {
+      Log.w("PrivacyScreen", "SharedPreference '" + KEY_PRIVACY_SCREEN_ENABLED + "' was not a Boolean value.", e);
+
+      if (shouldCorrect) {
+        if (convertStringEntryToBoolean()) {
+          return preferences.getBoolean(KEY_PRIVACY_SCREEN_ENABLED, defValue);
+        }
+        setPrivacyScreenEnabled(defValue);
+      }
+    }
+    return defValue;
+  }
+
+  /**
+   * Converts the entry from a {@link String} to {@link Boolean} if possible.
+   *
+   * @return true if the entry was a {@code String} value that could be resolved to a {@code Boolean} value, false otherwise.
+   * @see #isPrivacyScreenEnabled(boolean, boolean)
+   * @see #KEY_PRIVACY_SCREEN_ENABLED
+   */
+  private boolean convertStringEntryToBoolean() {
+    try {
+      String val = preferences.getString(KEY_PRIVACY_SCREEN_ENABLED, null);
+      if (val == null) {
+        return false;
+      }
+      if (val.equalsIgnoreCase("true")) {
+        setPrivacyScreenEnabled(true);
+        return true;
+      } else if (val.equalsIgnoreCase("false")) {
+        setPrivacyScreenEnabled(false);
+        return true;
+      }
+    } catch (ClassCastException e) {
+      Log.w("PrivacyScreen", "SharedPreference '" + KEY_PRIVACY_SCREEN_ENABLED + "' was not a String value.", e);
+    }
+    return false;
+  }
+
+  /**
+   * Sets the value of the Privacy Screen Enabled entry in {@link SharedPreferences}.
+   *
+   * @param value the value to set.
+   * @return true if successful, false otherwise.
+   * @see #KEY_PRIVACY_SCREEN_ENABLED
+   */
+  private boolean setPrivacyScreenEnabled(boolean value) {
+    preferences.edit().putBoolean(KEY_PRIVACY_SCREEN_ENABLED, value).apply();
+    return true;
+  }
+
+  @Override
+  public Object onMessage(String id, Object data) {
+    if (id == "isPrivacyScreenEnabled") {
+      boolean shouldCorrect = (data instanceof Boolean) && (data != null) && ((Boolean) data);
+      return isPrivacyScreenEnabled(true, shouldCorrect);
+    } else if (id == "setPrivacyScreenEnabled") {
+      if (data instanceof Boolean && data != null) {
+        return setPrivacyScreenEnabled((Boolean) data);
+      }
+      return false;
+    }
+    return null;
   }
 }