Add a setting to prevent screenshots from being taken (off by default)

app/src/main/java/org/fdroid/fdroid/FDroidApp.java

@@ -38,6 +38,7 @@ import android.os.StrictMode;
 import android.support.annotation.NonNull;
 import android.text.TextUtils;
 import android.util.Log;
+import android.view.WindowManager;
 import android.widget.Toast;
 
 import com.nostra13.universalimageloader.cache.disc.impl.LimitedAgeDiskCache;
@@ -126,6 +127,9 @@ public class FDroidApp extends Application {
 
     public void applyTheme(Activity activity) {
         activity.setTheme(getCurThemeResId());
+        if (Preferences.get().preventScreenshots()) {
+            activity.getWindow().addFlags(WindowManager.LayoutParams.FLAG_SECURE);
+        }
     }
 
     public static int getCurThemeResId() {

app/src/main/java/org/fdroid/fdroid/Preferences.java

@@ -38,6 +38,8 @@ public final class Preferences implements SharedPreferences.OnSharedPreferenceCh
                     .putString(PREF_LOCAL_REPO_NAME, getDefaultLocalRepoName())
                     .apply();
         }
+        defaultPreventScreenshots =
+                context.getResources().getBoolean(R.bool.defaultPreventScreenshots);
     }
 
     public static final String PREF_UPD_INTERVAL = "updateInterval";
@@ -66,6 +68,7 @@ public final class Preferences implements SharedPreferences.OnSharedPreferenceCh
     public static final String PREF_SHOW_NFC_DURING_SWAP = "showNfcDuringSwap";
     public static final String PREF_POST_PRIVILEGED_INSTALL = "postPrivilegedInstall";
     public static final String PREF_TRIED_EMPTY_UPDATE = "triedEmptyUpdate";
+    public static final String PREF_PREVENT_SCREENSHOTS = "preventScreenshots";
 
     private static final boolean DEFAULT_ROOTED = true;
     private static final boolean DEFAULT_HIDE_ANTI_FEATURE_APPS = false;
@@ -85,6 +88,7 @@ public final class Preferences implements SharedPreferences.OnSharedPreferenceCh
     private static final boolean DEFAULT_SHOW_NFC_DURING_SWAP = true;
     private static final boolean DEFAULT_FORCE_OLD_INDEX = false;
     private static final boolean DEFAULT_POST_PRIVILEGED_INSTALL = false;
+    private final boolean defaultPreventScreenshots;
 
     public enum Theme {
         light,
@@ -314,6 +318,10 @@ public final class Preferences implements SharedPreferences.OnSharedPreferenceCh
         }
     }
 
+    public boolean preventScreenshots() {
+        return preferences.getBoolean(PREF_PREVENT_SCREENSHOTS, defaultPreventScreenshots);
+    }
+
     /**
      * This is cached as it is called several times inside app list adapters.
      * Providing it here means the shared preferences file only needs to be

app/src/main/java/org/fdroid/fdroid/views/fragments/PreferencesFragment.java

@@ -12,6 +12,8 @@ import android.preference.Preference;
 import android.preference.PreferenceCategory;
 import android.support.v4.preference.PreferenceFragment;
 import android.text.TextUtils;
+import android.view.WindowManager;
+
 import com.geecko.QuickLyric.view.AppCompatListPreference;
 import info.guardianproject.netcipher.NetCipher;
 import info.guardianproject.netcipher.proxy.OrbotHelper;
@@ -377,6 +379,13 @@ public class PreferencesFragment extends PreferenceFragment
     public void onSharedPreferenceChanged(
             SharedPreferences sharedPreferences, String key) {
         updateSummary(key, true);
+        if (key.equals(Preferences.PREF_PREVENT_SCREENSHOTS)) {
+            if (Preferences.get().preventScreenshots()) {
+                getActivity().getWindow().addFlags(WindowManager.LayoutParams.FLAG_SECURE);
+            } else {
+                getActivity().getWindow().clearFlags(WindowManager.LayoutParams.FLAG_SECURE);
+            }
+        }
     }
 
 }

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

@@ -13,4 +13,8 @@
         <attr name="lightGrayTextColor" format="color" />
         <attr name="antiFeaturesWarning" format="reference" />
     </declare-styleable>
+
+    <!-- Default Preferences -->
+    <bool name="defaultPreventScreenshots">false</bool>
+
 </resources>

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

@@ -240,6 +240,10 @@ This often occurs with apps installed via Google Play or other sources, if they
     <string name="proxy_port">Proxy Port</string>
     <string name="proxy_port_summary">Your proxy\'s port number (e.g. 8118)</string>
 
+    <string name="privacy">Privacy</string>
+    <string name="preventScreenshots_title">Prevent Screenshots</string>
+    <string name="preventScreenshots_summary">Blocks screenshots from being taken and hides app content from recent apps screen</string>
+
     <!--
     status_download takes four parameters:
       - Repository (url)

app/src/main/res/xml/preferences.xml

@@ -89,6 +89,19 @@
             android:summary="@string/proxy_port_summary"
             android:dependency="enableProxy" />
     </PreferenceCategory>
+
+    <PreferenceCategory
+        android:key="pref_category_privacy"
+        android:title="@string/privacy">
+
+        <CheckBoxPreference
+            android:defaultValue="@bool/defaultPreventScreenshots"
+            android:key="preventScreenshots"
+            android:summary="@string/preventScreenshots_summary"
+            android:title="@string/preventScreenshots_title"/>
+
+    </PreferenceCategory>
+
     <PreferenceCategory android:title="@string/other"
         android:key="pref_category_other">
         <com.geecko.QuickLyric.view.AppCompatListPreference android:title="@string/cache_downloaded"