Registering and unregistering listeners based on activity lifecycle instead of view attach

Author: ajungg

ui/src/main/java/io/snabble/sdk/ui/checkout/CheckoutView.java

@@ -1,5 +1,7 @@
 package io.snabble.sdk.ui.checkout;
 
+import android.app.Activity;
+import android.app.Application;
 import android.app.ProgressDialog;
 import android.content.Context;
 import android.content.DialogInterface;
@@ -16,6 +18,8 @@
 import io.snabble.sdk.ui.R;
 import io.snabble.sdk.ui.SnabbleUI;
 import io.snabble.sdk.ui.utils.DelayedProgressDialog;
+import io.snabble.sdk.ui.utils.UIUtils;
+import io.snabble.sdk.utils.SimpleActivityLifecycleCallbacks;
 
 public class CheckoutView extends FrameLayout implements Checkout.OnCheckoutStateChangedListener {
     private ViewAnimator viewAnimator;
@@ -126,22 +130,52 @@ public void displayView(View view) {
                 ViewGroup.LayoutParams.MATCH_PARENT));
     }
 
+    public void registerListeners() {
+        checkout.addOnCheckoutStateChangedListener(this);
+        progressDialog.setOnCancelListener(onCancelListener);
+    }
+
+    public void unregisterListeners() {
+        checkout.removeOnCheckoutStateChangedListener(this);
+
+        progressDialog.setOnCancelListener(null);
+        progressDialog.dismiss();
+    }
+
     @Override
-    protected void onAttachedToWindow() {
+    public void onAttachedToWindow() {
         super.onAttachedToWindow();
 
-        checkout.addOnCheckoutStateChangedListener(this);
+        Application application = (Application) getContext().getApplicationContext();
+        application.registerActivityLifecycleCallbacks(activityLifecycleCallbacks);
 
-        progressDialog.setOnCancelListener(onCancelListener);
+        registerListeners();
     }
 
     @Override
-    protected void onDetachedFromWindow() {
+    public void onDetachedFromWindow() {
         super.onDetachedFromWindow();
 
-        checkout.removeOnCheckoutStateChangedListener(this);
+        Application application = (Application) getContext().getApplicationContext();
+        application.unregisterActivityLifecycleCallbacks(activityLifecycleCallbacks);
 
-        progressDialog.setOnCancelListener(null);
-        progressDialog.dismiss();
+        unregisterListeners();
     }
+
+    private Application.ActivityLifecycleCallbacks activityLifecycleCallbacks =
+            new SimpleActivityLifecycleCallbacks() {
+                @Override
+                public void onActivityStarted(Activity activity) {
+                    if (UIUtils.getHostActivity(getContext()) == activity) {
+                        registerListeners();
+                    }
+                }
+
+                @Override
+                public void onActivityStopped(Activity activity) {
+                    if (UIUtils.getHostActivity(getContext()) == activity) {
+                        unregisterListeners();
+                    }
+                }
+            };
 }