android: keep a pointer on the global Java VM instead of the current

environment, so back-to-jvm techniques can work from any thread.

src/Makefile.am

@@ -9,7 +9,7 @@ liblol_a_SOURCES = \
     timer.cpp timer.h bitfield.h profiler.cpp profiler.h input.h input.cpp \
     world.cpp world.h sample.cpp sample.h sampler.cpp sampler.h \
     text.cpp text.h emitter.cpp emitter.h numeric.h hash.cpp hash.h \
-    worldentity.cpp worldentity.h image.cpp image.h gradient.cpp gradient.h \
+    worldentity.cpp worldentity.h gradient.cpp gradient.h \
     platform.cpp platform.h sprite.cpp sprite.h \
     \
     sdlapp.cpp sdlapp.h sdlinput.cpp sdlinput.h \
@@ -20,6 +20,8 @@ liblol_a_SOURCES = \
     \
     shader/shader.cpp shader/shader.h \
     \
+    image/image.cpp image/image.h \
+    \
     loldebug.h \
     debug/fps.cpp debug/fps.h debug/sphere.cpp debug/sphere.h \
     debug/record.cpp debug/record.h debug/stats.cpp debug/stats.h \

src/androidapp.cpp

@@ -25,13 +25,14 @@ using namespace lol;
 
 namespace lol
 {
-jobject g_ctx;
-JNIEnv *g_env;
+JavaVM *g_vm;
+jobject g_activity;
 };
 
 extern "C" jint
 JNI_OnLoad(JavaVM* vm, void* reserved)
 {
+    g_vm = vm;
     return JNI_VERSION_1_4;
 }
 
@@ -39,16 +40,12 @@ extern "C" void
 Java_org_zoy_LolEngine_LolActivity_nativeInit(JNIEnv* env, jobject thiz)
 {
     env->NewGlobalRef(thiz); /* FIXME: never released! */
-    g_ctx = thiz;
+    g_activity = thiz;
 }
 
 extern "C" void
 Java_org_zoy_LolEngine_LolRenderer_nativeInit(JNIEnv* env)
 {
-    /* We cannot use JNI_OnLoad for this because we're in a different
-     * thread now. */
-    g_env = env;
-
     Log::Info("initialising renderer");
     Ticker::Setup(30.0f);
     Video::Setup(ivec2(320, 200));

src/core.h

@@ -49,7 +49,7 @@
 #include "map.h"
 #include "layer.h"
 #include "shader/shader.h"
-#include "image.h"
+#include "image/image.h"
 
 // Managers
 #include "ticker.h"

src/image.cpp → src/image/image.cpp

@@ -35,8 +35,8 @@ namespace lol
 {
 
 #if defined ANDROID_NDK
-extern JNIEnv *g_env;
-extern jobject g_ctx;
+extern JavaVM *g_vm;
+extern jobject g_activity;
 #endif
 
 /*
@@ -126,14 +126,23 @@ Image::Image(char const *path)
     data->size = ivec2(data->img->w, data->img->h);
     data->format = data->img->format->Amask ? FORMAT_RGBA : FORMAT_RGB;
 #elif defined ANDROID_NDK
-    jclass cls = g_env->GetObjectClass(g_ctx);
+    JNIEnv *env;
+    jint res = g_vm->GetEnv((void **)&env, JNI_VERSION_1_2);
+    if (res < 0)
+    {
+#if !LOL_RELEASE
+        Log::Error("could not get JVM environment\n");
+#endif
+        exit(1);
+    }
+    jclass cls = env->GetObjectClass(g_activity);
     jmethodID mid;
 
-    mid = g_env->GetMethodID(cls, "openImage",
-                             "(Ljava/lang/String;)Landroid/graphics/Bitmap;");
-    jstring name = g_env->NewStringUTF(path);
-    data->bmp = g_env->CallObjectMethod(g_ctx, mid, name);
-    g_env->DeleteLocalRef(name);
+    mid = env->GetMethodID(cls, "openImage",
+                           "(Ljava/lang/String;)Landroid/graphics/Bitmap;");
+    jstring name = env->NewStringUTF(path);
+    data->bmp = env->CallObjectMethod(g_activity, mid, name);
+    env->DeleteLocalRef(name);
     if (!data->bmp)
     {
 #if !LOL_RELEASE
@@ -141,21 +150,21 @@ Image::Image(char const *path)
 #endif
         exit(1);
     }
-    g_env->NewGlobalRef(data->bmp);
+    env->NewGlobalRef(data->bmp);
 
     /* Get image dimensions */
-    mid = g_env->GetMethodID(cls, "getWidth", "(Landroid/graphics/Bitmap;)I");
-    data->size.x = g_env->CallIntMethod(g_ctx, mid, data->bmp);
-    mid = g_env->GetMethodID(cls, "getHeight", "(Landroid/graphics/Bitmap;)I");
-    data->size.y = g_env->CallIntMethod(g_ctx, mid, data->bmp);
+    mid = env->GetMethodID(cls, "getWidth", "(Landroid/graphics/Bitmap;)I");
+    data->size.x = env->CallIntMethod(g_activity, mid, data->bmp);
+    mid = env->GetMethodID(cls, "getHeight", "(Landroid/graphics/Bitmap;)I");
+    data->size.y = env->CallIntMethod(g_activity, mid, data->bmp);
 
     /* Get pixels */
-    data->array = g_env->NewIntArray(data->size.x * data->size.y);
-    g_env->NewGlobalRef(data->array);
-    mid = g_env->GetMethodID(cls, "getPixels", "(Landroid/graphics/Bitmap;[I)V");
-    g_env->CallVoidMethod(g_ctx, mid, data->bmp, data->array);
+    data->array = env->NewIntArray(data->size.x * data->size.y);
+    env->NewGlobalRef(data->array);
+    mid = env->GetMethodID(cls, "getPixels", "(Landroid/graphics/Bitmap;[I)V");
+    env->CallVoidMethod(g_activity, mid, data->bmp, data->array);
 
-    data->pixels = g_env->GetIntArrayElements(data->array, 0);
+    data->pixels = env->GetIntArrayElements(data->array, 0);
     for (int n = 0; n < data->size.x * data->size.y; n++)
     {
         uint32_t u = data->pixels[n];
@@ -343,16 +352,25 @@ Image::~Image()
 #elif defined USE_SDL
     SDL_FreeSurface(data->img);
 #elif defined ANDROID_NDK
-    jclass cls = g_env->GetObjectClass(g_ctx);
+    JNIEnv *env;
+    jint res = g_vm->GetEnv((void **)&env, JNI_VERSION_1_2);
+    if (res < 0)
+    {
+#if !LOL_RELEASE
+        Log::Error("could not get JVM environment\n");
+#endif
+        exit(1);
+    }
+    jclass cls = env->GetObjectClass(g_activity);
     jmethodID mid;
 
-    g_env->ReleaseIntArrayElements(data->array, data->pixels, 0);
-    g_env->DeleteGlobalRef(data->array);
+    env->ReleaseIntArrayElements(data->array, data->pixels, 0);
+    env->DeleteGlobalRef(data->array);
 
     /* Free image */
-    mid = g_env->GetMethodID(cls, "closeImage", "(Landroid/graphics/Bitmap;)V");
-    g_env->CallVoidMethod(g_ctx, mid, data->bmp);
-    g_env->DeleteGlobalRef(data->bmp);
+    mid = env->GetMethodID(cls, "closeImage", "(Landroid/graphics/Bitmap;)V");
+    env->CallVoidMethod(g_activity, mid, data->bmp);
+    env->DeleteGlobalRef(data->bmp);
 #elif defined __CELLOS_LV2__
     free(data->pixels);
 #else