New JNI bindings

jni/JniEventCallback.cpp

+/*
+ * This file is part of Adblock Plus <http://adblockplus.org/>,
+ * Copyright (C) 2006-2014 Eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "JniCallbacks.h"
+
+AdblockPlus::Android::JniEventCallback::JniEventCallback(JNIEnv* env, jobject callbackObject) :

[Felix Dahlke, 2014/03/28 08:29:00]

Should be broken before ":",  not after it, according to Mozilla's rules.

+    JniCallbackBase(env, callbackObject)
+{
+}
+
+AdblockPlus::Android::JniEventCallback::~JniEventCallback()
+{
+}
+
+void AdblockPlus::Android::JniEventCallback::Callback(AdblockPlus::JsValueList& params)
+{
+  AdblockPlus::Android::JNIEnvAcquire env(GetJavaVM());

[Felix Dahlke, 2014/03/28 08:29:00]

Capitalisation is inconsistent here, "JniEventCallback" vs "JNIEnvAcquire" and
"GetJavaVM". Don't have a strong preference, but I think it should be
consistent.

[René Jeschke, 2014/03/28 10:59:15]

It is called JNIEnvAcquire because it acquires a thing of type 'JNIEnv*', so the
name is correct IMHO. 'GetJavaVM' also returns a 'JavaVM*'.

[Felix Dahlke, 2014/03/28 11:27:18]

Yeah you're right, that's better.

+
+  jclass clazz = env->GetObjectClass(GetCallbackObject());
+  jmethodID method = env->GetMethodID(clazz, "eventCallback", "(Ljava/util/List;)V");
+
+  if (method)
+  {
+    jobject jsList = AdblockPlus::Android::JniJsValueList2ArrayList(*env, params);
+    env->CallVoidMethod(GetCallbackObject(), method, jsList);
+  }
+}
+
+static jlong JNICALL JniCtor(JNIEnv* env, jclass clazz, jobject callbackObject)

[Felix Dahlke, 2014/03/28 08:29:00]

We mostly use unnamed namespaces instead of static in new code (added a hint to
that to the coding style), but it doesn't matter too much as long as its
consistent on a per-file basis.

That said, I think we should move all the static locals up, before the member
function definitions etc. That's where the anonymous namespace usually goes,
should help avoid confusion.

+{
+  TRY
+  {
+    return AdblockPlus::Android::JniPtr2Long(new AdblockPlus::Android::JniEventCallback(env, callbackObject));
+  }
+  CATCH_THROW_AND_RETURN(env, 0)
+}
+
+static void JNICALL JniDtor(JNIEnv* env, jclass clazz, jlong ptr)
+{
+  delete AdblockPlus::Android::JniLong2TypePtr<AdblockPlus::Android::JniEventCallback>(ptr);

[Felix Dahlke, 2014/03/28 08:29:00]

I'd much prefer "JniLongToTypePtr" since this had me puzzled for a while :)

Same for the others.

+}
+
+static JNINativeMethod methods[] =
+{
+{ (char*)"ctor", (char*)"(Ljava/lang/Object;)J", (void*)JniCtor },

[Felix Dahlke, 2014/03/28 08:29:00]

1. Note that as per our coding style, new code should only use C-style casts
when we need its exact semantics, which is not the case here. However, in this
particular case I think it's obvious enough what happens (casting literals and
casting stuff to void*), and it'd be awkwardly long with C++-style casts, so I'm
quite fine with this.
2. I think it'd be more in line with our code style if this and the following
line where indented, and if the closing }; was on its own line.

+{ (char*)"dtor", (char*)"(J)V", (void*)JniDtor }, };
+
+extern "C" JNIEXPORT void JNICALL Java_org_adblockplus_android_api_EventCallback_registerNatives(JNIEnv *env, jclass clazz)
+{
+  env->RegisterNatives(clazz, methods, sizeof(methods) / sizeof(methods[0]));
+}