Android: Display Panic Alerts on-screen as an Android Toast message.

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/NativeLibrary.java

@@ -8,6 +8,9 @@ package org.dolphinemu.dolphinemu;
 
 import android.util.Log;
 import android.view.Surface;
+import android.widget.Toast;
+
+import org.dolphinemu.dolphinemu.activities.EmulationActivity;
 
 /**
  * Class which contains methods that interact
@@ -15,6 +18,8 @@ import android.view.Surface;
  */
 public final class NativeLibrary
 {
+	private static EmulationActivity mEmulationActivity;
+
 	/**
 	 * Button type for use in onTouchEvent
 	 */
@@ -235,6 +240,13 @@ public final class NativeLibrary
 	/** Native EGL functions not exposed by Java bindings **/
 	public static native void eglBindAPI(int api);
 
+	/**
+	 * The methods C++ uses to find references to Java classes and methods
+	 * are really expensive. Rather than calling them every time we want to
+	 * run them, do it once when we load the native library.
+	 */
+	private static native void CacheClassesAndMethods();
+
 	static
 	{
 		try
@@ -245,5 +257,26 @@ public final class NativeLibrary
 		{
 			Log.e("NativeLibrary", ex.toString());
 		}
+
+		CacheClassesAndMethods();
+	}
+
+	public static void displayAlertMsg(final String alert)
+	{
+		Log.e("DolphinEmu", "Alert: " + alert);
+		mEmulationActivity.runOnUiThread(new Runnable()
+		{
+			@Override
+			public void run()
+			{
+				Toast.makeText(mEmulationActivity, "Panic Alert: " + alert, Toast.LENGTH_LONG).show();
+			}
+		});
+	}
+
+	public static void setEmulationActivity(EmulationActivity emulationActivity)
+	{
+		Log.v("DolphinEmu", "Registering EmulationActivity.");
+		mEmulationActivity = emulationActivity;
 	}
 }

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/activities/EmulationActivity.java

@@ -7,6 +7,7 @@ import android.content.Intent;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
+import android.util.Log;
 import android.view.InputDevice;
 import android.view.KeyEvent;
 import android.view.Menu;
@@ -91,6 +92,23 @@ public final class EmulationActivity extends Activity
 				.commit();
 	}
 
+	@Override
+	protected void onStart()
+	{
+		super.onStart();
+		Log.d("DolphinEmu", "EmulationActivity starting.");
+		NativeLibrary.setEmulationActivity(this);
+	}
+
+	@Override
+	protected void onStop()
+	{
+		super.onStop();
+		Log.d("DolphinEmu", "EmulationActivity stopping.");
+
+		NativeLibrary.setEmulationActivity(null);
+	}
+
 	@Override
 	protected void onPostCreate(Bundle savedInstanceState)
 	{

Source/Core/DolphinWX/MainAndroid.cpp

@@ -37,6 +37,10 @@ ANativeWindow* surf;
 std::string g_filename;
 std::string g_set_userpath = "";
 
+JavaVM* g_java_vm;
+jclass g_jni_class;
+jmethodID g_jni_method_alert;
+
 // PanicAlert
 static bool g_alert_available = false;
 static std::string g_alert_message = "";
@@ -44,6 +48,16 @@ static Common::Event g_alert_event;
 
 #define DOLPHIN_TAG "DolphinEmuNative"
 
+/*
+ * Cache the JavaVM so that we can call into it later.
+ */
+jint JNI_OnLoad(JavaVM* vm, void* reserved)
+{
+	g_java_vm = vm;
+
+	return JNI_VERSION_1_6;
+}
+
 void Host_NotifyMapLoaded() {}
 void Host_RefreshDSPDebuggerWindow() {}
 
@@ -99,6 +113,18 @@ void Host_ShowVideoConfig(void*, const std::string&, const std::string&) {}
 
 static bool MsgAlert(const char* caption, const char* text, bool yes_no, int /*Style*/)
 {
+	__android_log_print(ANDROID_LOG_ERROR, DOLPHIN_TAG, "%s:%s", caption, text);
+
+	// Associate the current Thread with the Java VM.
+	JNIEnv* env;
+	g_java_vm->AttachCurrentThread(&env, NULL);
+
+	// Execute the Java method.
+	env->CallStaticVoidMethod(g_jni_class, g_jni_method_alert, env->NewStringUTF(text));
+
+	// Must be called before the current thread exits; might as well do it here.
+	g_java_vm->DetachCurrentThread();
+
 	g_alert_message = std::string(text);
 	g_alert_available = true;
 	// XXX: Uncomment next line when the Android UI actually handles messages
@@ -365,10 +391,11 @@ JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_SetProfiling
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_WriteProfileResults(JNIEnv *env, jobject obj);
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_Run(JNIEnv *env, jobject obj, jobject _surf);
 
-// MsgAlert
+// Msg
 JNIEXPORT jboolean JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_HasAlertMsg(JNIEnv *env, jobject obj);
 JNIEXPORT jstring JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_GetAlertMsg(JNIEnv *env, jobject obj);
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_ClearAlertMsg(JNIEnv *env, jobject obj);
+JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_CacheClassesAndMethods(JNIEnv *env, jobject obj);
 
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_UnPauseEmulation(JNIEnv *env, jobject obj)
 {
@@ -579,6 +606,22 @@ JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_ClearAlertMs
 	g_alert_event.Set(); // Kick the alert
 }
 
+JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_CacheClassesAndMethods(JNIEnv *env, jobject obj)
+{
+	// This class reference is only valid for the lifetime of this method.
+	jclass localClass = env->FindClass("org/dolphinemu/dolphinemu/NativeLibrary");
+
+	// This reference, however, is valid until we delete it.
+	g_jni_class = reinterpret_cast<jclass>(env->NewGlobalRef(localClass));
+
+	// TODO Find a place for this.
+	// So we don't leak a reference to NativeLibrary.class.
+	// env->DeleteGlobalRef(g_jni_class);
+
+	// Method signature taken from javap -s Source/Android/app/build/intermediates/classes/arm/debug/org/dolphinemu/dolphinemu/NativeLibrary.class
+	g_jni_method_alert = env->GetStaticMethodID(g_jni_class, "displayAlertMsg", "(Ljava/lang/String;)V");
+}
+
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_Run(JNIEnv *env, jobject obj, jobject _surf)
 {
 	surf = ANativeWindow_fromSurface(env, _surf);