Android: bailout in ComponentPeerView’s callbacks if underlying host is deleted.

Previously we saw a crash in onTouchEvent due to host being 0 while the callback was called. Just as a precaution we add this check to other callbacks too.

modules/juce_core/native/java/JuceAppActivity.java

@@ -566,6 +566,9 @@ public class JuceAppActivity   extends Activity
         @Override
         public void onDraw (Canvas canvas)
         {
+            if (host == 0)
+                return;
+
             handlePaint (host, canvas, paint);
         }
 
@@ -657,6 +660,9 @@ public class JuceAppActivity   extends Activity
         @Override
         public boolean onKeyDown (int keyCode, KeyEvent event)
         {
+            if (host == 0)
+                return false;
+
             switch (keyCode)
             {
                 case KeyEvent.KEYCODE_VOLUME_UP:
@@ -679,6 +685,9 @@ public class JuceAppActivity   extends Activity
         @Override
         public boolean onKeyUp (int keyCode, KeyEvent event)
         {
+            if (host == 0)
+                return false;
+
             handleKeyUp (host, keyCode, event.getUnicodeChar());
             return true;
         }
@@ -686,6 +695,9 @@ public class JuceAppActivity   extends Activity
         @Override
         public boolean onKeyMultiple (int keyCode, int count, KeyEvent event)
         {
+            if (host == 0)
+                return false;
+
             if (keyCode != KeyEvent.KEYCODE_UNKNOWN || event.getAction() != KeyEvent.ACTION_MULTIPLE)
                 return super.onKeyMultiple (keyCode, count, event);
 
@@ -718,6 +730,9 @@ public class JuceAppActivity   extends Activity
         @Override
         protected void onSizeChanged (int w, int h, int oldw, int oldh)
         {
+            if (host == 0)
+                return;
+
             super.onSizeChanged (w, h, oldw, oldh);
             viewSizeChanged (host);
         }
@@ -734,6 +749,9 @@ public class JuceAppActivity   extends Activity
         @Override
         public void onFocusChange (View v, boolean hasFocus)
         {
+            if (host == 0)
+                return;
+
             if (v == this)
                 focusChanged (host, hasFocus);
         }