kill python thread on exit and handle back button

Author: bobatsar

pythonforandroid/bootstraps/webview/build/src/org/kivy/android/PythonActivity.java

@@ -180,7 +180,15 @@ public boolean shouldOverrideUrlLoading(WebView view, String url) {
 
         final Thread wvThread = new Thread(new WebViewLoaderMain(), "WvThread");
         wvThread.start();
+    }
 
+    @Override
+    public void onDestroy() {
+        Log.i("Destroy", "end of app");
+        super.onDestroy();
+        
+        // make sure all child threads (python_thread) are stopped
+        android.os.Process.killProcess(android.os.Process.myPid());
     }
 
     public void loadLibraries() {
@@ -297,6 +305,27 @@ public static ViewGroup getLayout() {
         return   mLayout;
     }
 
+    long lastBackClick = SystemClock.elapsedRealtime();
+    @Override
+    public boolean onKeyDown(int keyCode, KeyEvent event) {
+        // Check if the key event was the Back button and if there's history
+        if ((keyCode == KeyEvent.KEYCODE_BACK) && mWebView.canGoBack()) {
+            mWebView.goBack();
+            return true;
+        }
+        // If it wasn't the Back key or there's no web page history, bubble up to the default
+        // system behavior (probably exit the activity)
+        if (SystemClock.elapsedRealtime() - lastBackClick > 2000){
+            lastBackClick = SystemClock.elapsedRealtime();
+            Toast.makeText(this, "Click again to close the app",
+            Toast.LENGTH_LONG).show();
+            return true;
+        }
+
+        lastBackClick = SystemClock.elapsedRealtime();
+        return super.onKeyDown(keyCode, event);
+    }
+
 
     //----------------------------------------------------------------------------
     // Listener interface for onNewIntent
@@ -367,7 +396,7 @@ protected void onActivityResult(int requestCode, int resultCode, Intent intent)
         }
     }
 
-	public static void start_service(String serviceTitle, String serviceDescription,
+    public static void start_service(String serviceTitle, String serviceDescription,
                 String pythonServiceArgument) {
         Intent serviceIntent = new Intent(PythonActivity.mActivity, PythonService.class);
         String argument = PythonActivity.mActivity.getFilesDir().getAbsolutePath();

pythonforandroid/toolchain.py

@@ -118,6 +118,13 @@ def build_dist_from_args(ctx, dist, args):
     ctx.recipe_build_order = build_order
     ctx.python_modules = python_modules
 
+    if python_modules and hasattr(sys, 'real_prefix'):
+        error('virtualenv is needed to install pure-Python modules, but')
+        error('virtualenv does not support nesting, and you are running')
+        error('python-for-android in one. Please run p4a outside of a')
+        error('virtualenv instead.')
+        exit(1)
+
     info('The selected bootstrap is {}'.format(bs.name))
     info_main('# Creating dist with {} bootstrap'.format(bs.name))
     bs.distribution = dist