Android: Add enablers for listening to activity results

When you launch an activity through an intent,
data can be provided back from the activity when it has finished
using onActivityResult() in the activity which launched it.

This is okay for applications, since they can easily create their
own activities, but does not work for libraries that need to
use intents. There is no listener API for activity results which
allow external classes to eavesdrop.

In order to support launching intents from third-party or add-on
libraries, we provide a low-level way to hook into the activity
result event. The corresponding public API will be added to
QtAndroidExtras.

Change-Id: I89417f485e2c0e69028dcccc7c155788346a7417
Reviewed-by: Christian Stromme <christian.stromme@digia.com>

src/android/jar/src/org/qtproject/qt5/android/QtActivityDelegate.java

@@ -44,6 +44,7 @@ package org.qtproject.qt5.android;
 
 import android.app.Activity;
 import android.content.Context;
+import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.content.res.Configuration;
@@ -86,6 +87,7 @@ public class QtActivityDelegate
     private Method m_super_onKeyDown = null;
     private Method m_super_onKeyUp = null;
     private Method m_super_onConfigurationChanged = null;
+    private Method m_super_onActivityResult = null;
 
     private static final String NATIVE_LIBRARIES_KEY = "native.libraries";
     private static final String BUNDLED_LIBRARIES_KEY = "bundled.libraries";
@@ -410,6 +412,7 @@ public class QtActivityDelegate
             m_super_onKeyDown = m_activity.getClass().getMethod("super_onKeyDown", Integer.TYPE, KeyEvent.class);
             m_super_onKeyUp = m_activity.getClass().getMethod("super_onKeyUp", Integer.TYPE, KeyEvent.class);
             m_super_onConfigurationChanged = m_activity.getClass().getMethod("super_onConfigurationChanged", Configuration.class);
+            m_super_onActivityResult = m_activity.getClass().getMethod("super_onActivityResult", Integer.TYPE, Integer.TYPE, Intent.class);
         } catch (Exception e) {
             e.printStackTrace();
             return false;
@@ -720,6 +723,18 @@ public class QtActivityDelegate
         }
     }
 
+    public void onActivityResult(int requestCode, int resultCode, Intent data)
+    {
+        try {
+            m_super_onActivityResult.invoke(m_activity, requestCode, resultCode, data);
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+
+        QtNative.onActivityResult(requestCode, resultCode, data);
+    }
+
+
     public void onStop()
     {
         QtNative.updateApplicationState(ApplicationSuspended);

src/android/jar/src/org/qtproject/qt5/android/QtNative.java

@@ -598,4 +598,7 @@ public class QtNative
     public static native boolean onContextItemSelected(int itemId, boolean checked);
     public static native void onContextMenuClosed(Menu menu);
     // menu methods
+
+    // activity methods
+    public static native void onActivityResult(int requestCode, int resultCode, Intent data);
 }

src/corelib/kernel/qjnihelpers.cpp

@@ -40,6 +40,8 @@
 ****************************************************************************/
 
 #include "qjnihelpers_p.h"
+#include "qmutex.h"
+#include "qlist.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -48,6 +50,39 @@ static jobject g_jActivity = Q_NULLPTR;
 static jobject g_jClassLoader = Q_NULLPTR;
 static jint g_androidSdkVersion = 0;
 
+namespace {
+    class ActivityResultListeners
+    {
+    public:
+        QMutex mutex;
+        QList<QtAndroidPrivate::ActivityResultListener *> listeners;
+    };
+}
+
+Q_GLOBAL_STATIC(ActivityResultListeners, g_activityResultListeners)
+
+void QtAndroidPrivate::registerActivityResultListener(ActivityResultListener *listener)
+{
+    QMutexLocker locker(&g_activityResultListeners()->mutex);
+    g_activityResultListeners()->listeners.append(listener);
+}
+
+void QtAndroidPrivate::unregisterActivityResultListener(ActivityResultListener *listener)
+{
+    QMutexLocker locker(&g_activityResultListeners()->mutex);
+    g_activityResultListeners()->listeners.removeAll(listener);
+}
+
+void QtAndroidPrivate::handleActivityResult(jint requestCode, jint resultCode, jobject data)
+{
+    QMutexLocker locker(&g_activityResultListeners()->mutex);
+    const QList<QtAndroidPrivate::ActivityResultListener *> &listeners = g_activityResultListeners()->listeners;
+    for (int i=0; i<listeners.size(); ++i) {
+        if (listeners.at(i)->handleActivityResult(requestCode, resultCode, data))
+            break;
+    }
+}
+
 static inline bool exceptionCheck(JNIEnv *env)
 {
     if (env->ExceptionCheck()) {

src/corelib/kernel/qjnihelpers_p.h

@@ -60,11 +60,22 @@ QT_BEGIN_NAMESPACE
 
 namespace QtAndroidPrivate
 {
+    class Q_CORE_EXPORT ActivityResultListener
+    {
+    public:
+        virtual ~ActivityResultListener() {}
+        virtual bool handleActivityResult(jint requestCode, jint resultCode, jobject data) = 0;
+    };
+
     Q_CORE_EXPORT jobject activity();
     Q_CORE_EXPORT JavaVM *javaVM();
     Q_CORE_EXPORT jint initJNI(JavaVM *vm, JNIEnv *env);
     jobject classLoader();
     Q_CORE_EXPORT jint androidSdkVersion();
+
+    Q_CORE_EXPORT void handleActivityResult(jint requestCode, jint resultCode, jobject data);
+    Q_CORE_EXPORT void registerActivityResultListener(ActivityResultListener *listener);
+    Q_CORE_EXPORT void unregisterActivityResultListener(ActivityResultListener *listener);
 }
 
 QT_END_NAMESPACE

src/plugins/platforms/android/androidjnimain.cpp

@@ -71,6 +71,7 @@
 #include <android/asset_manager_jni.h>
 #include "qandroidassetsfileenginehandler.h"
 #include <android/api-level.h>
+#include <QtCore/private/qjnihelpers_p.h>
 
 #include <qpa/qwindowsysteminterface.h>
 
@@ -621,6 +622,14 @@ static void handleOrientationChanged(JNIEnv */*env*/, jobject /*thiz*/, jint new
     }
 }
 
+static void onActivityResult(JNIEnv */*env*/, jclass /*cls*/,
+                             jint requestCode,
+                             jint resultCode,
+                             jobject data)
+{
+    QtAndroidPrivate::handleActivityResult(requestCode, resultCode, data);
+}
+
 static JNINativeMethod methods[] = {
     {"startQtAndroidPlugin", "()Z", (void *)startQtAndroidPlugin},
     {"startQtApplication", "(Ljava/lang/String;Ljava/lang/String;)V", (void *)startQtApplication},
@@ -630,7 +639,8 @@ static JNINativeMethod methods[] = {
     {"setSurface", "(ILjava/lang/Object;II)V", (void *)setSurface},
     {"updateWindow", "()V", (void *)updateWindow},
     {"updateApplicationState", "(I)V", (void *)updateApplicationState},
-    {"handleOrientationChanged", "(II)V", (void *)handleOrientationChanged}
+    {"handleOrientationChanged", "(II)V", (void *)handleOrientationChanged},
+    {"onActivityResult", "(IILandroid/content/Intent;)V", (void *)onActivityResult}
 };
 
 #define FIND_AND_CHECK_CLASS(CLASS_NAME) \