Fixes bug #1889, allows for GL Context deletion/recreation on Android

Thanks ny00!

android-project/src/org/libsdl/app/SDLActivity.java

@@ -72,6 +72,7 @@ public class SDLActivity extends Activity {
         // Set up the surface
         mEGLSurface = EGL10.EGL_NO_SURFACE;
         mSurface = new SDLSurface(getApplication());
+        mEGLContext = EGL10.EGL_NO_CONTEXT;
 
         mLayout = new AbsoluteLayout(this);
         mLayout.addView(mSurface);
@@ -250,6 +251,20 @@ public class SDLActivity extends Activity {
         return initEGL(majorVersion, minorVersion, attribs);
     }
     
+    public static void deleteGLContext() {
+        if (SDLActivity.mEGLDisplay != null && SDLActivity.mEGLContext != EGL10.EGL_NO_CONTEXT) {
+            EGL10 egl = (EGL10)EGLContext.getEGL();
+            egl.eglMakeCurrent(SDLActivity.mEGLDisplay, EGL10.EGL_NO_SURFACE, EGL10.EGL_NO_SURFACE, EGL10.EGL_NO_CONTEXT);
+            egl.eglDestroyContext(SDLActivity.mEGLDisplay, SDLActivity.mEGLContext);
+            SDLActivity.mEGLContext = EGL10.EGL_NO_CONTEXT;
+
+            if (SDLActivity.mEGLSurface != EGL10.EGL_NO_SURFACE) {
+                egl.eglDestroySurface(SDLActivity.mEGLDisplay, SDLActivity.mEGLSurface);
+                SDLActivity.mEGLSurface = EGL10.EGL_NO_SURFACE;
+            }
+        }
+    }
+
     public static void flipBuffers() {
         flipEGL();
     }
@@ -314,19 +329,20 @@ public class SDLActivity extends Activity {
     // EGL functions
     public static boolean initEGL(int majorVersion, int minorVersion, int[] attribs) {
         try {
+            EGL10 egl = (EGL10)EGLContext.getEGL();
+            
             if (SDLActivity.mEGLDisplay == null) {
-                Log.v("SDL", "Starting up OpenGL ES " + majorVersion + "." + minorVersion);
+                SDLActivity.mEGLDisplay = egl.eglGetDisplay(EGL10.EGL_DEFAULT_DISPLAY);
-
-                EGL10 egl = (EGL10)EGLContext.getEGL();
-
-                EGLDisplay dpy = egl.eglGetDisplay(EGL10.EGL_DEFAULT_DISPLAY);
-
                 int[] version = new int[2];
-                egl.eglInitialize(dpy, version);
+                egl.eglInitialize(SDLActivity.mEGLDisplay, version);
+            }
             
+            if (SDLActivity.mEGLDisplay != null && SDLActivity.mEGLContext == EGL10.EGL_NO_CONTEXT) {
+                // No current GL context exists, we will create a new one.
+                Log.v("SDL", "Starting up OpenGL ES " + majorVersion + "." + minorVersion);
                 EGLConfig[] configs = new EGLConfig[128];
                 int[] num_config = new int[1];
-                if (!egl.eglChooseConfig(dpy, attribs, configs, 1, num_config) || num_config[0] == 0) {
+                if (!egl.eglChooseConfig(SDLActivity.mEGLDisplay, attribs, configs, 1, num_config) || num_config[0] == 0) {
                     Log.e("SDL", "No EGL config available");
                     return false;
                 }
@@ -350,7 +366,7 @@ public class SDLActivity extends Activity {
                             attribs[j] == EGL10.EGL_ALPHA_SIZE ||
                             attribs[j] == EGL10.EGL_DEPTH_SIZE ||
                             attribs[j] == EGL10.EGL_STENCIL_SIZE)) {
-                            egl.eglGetConfigAttrib(dpy, configs[i], attribs[j], value);
+                            egl.eglGetConfigAttrib(SDLActivity.mEGLDisplay, configs[i], attribs[j], value);
                             bitdiff += value[0] - attribs[j + 1]; // value is always >= attrib
                         }
                     }
@@ -365,12 +381,11 @@ public class SDLActivity extends Activity {
                 
                 Log.d("SDL", "Selected mode with a total bit difference of " + bestdiff);
 
-
-                SDLActivity.mEGLDisplay = dpy;
                 SDLActivity.mEGLConfig = config;
                 SDLActivity.mGLMajor = majorVersion;
                 SDLActivity.mGLMinor = minorVersion;
             }
+            
             return SDLActivity.createEGLSurface();
 
         } catch(Exception e) {
@@ -397,7 +412,7 @@ public class SDLActivity extends Activity {
     public static boolean createEGLSurface() {
         if (SDLActivity.mEGLDisplay != null && SDLActivity.mEGLConfig != null) {
             EGL10 egl = (EGL10)EGLContext.getEGL();
-            if (SDLActivity.mEGLContext == null) createEGLContext();
+            if (SDLActivity.mEGLContext == EGL10.EGL_NO_CONTEXT) createEGLContext();
 
             if (SDLActivity.mEGLSurface == EGL10.EGL_NO_SURFACE) {
                 Log.v("SDL", "Creating new EGL Surface");

src/core/android/SDL_android.c

@@ -71,6 +71,7 @@ static jclass mActivityClass;
 
 // method signatures
 static jmethodID midCreateGLContext;
+static jmethodID midDeleteGLContext;
 static jmethodID midFlipBuffers;
 static jmethodID midAudioInit;
 static jmethodID midAudioWriteShortBuffer;
@@ -120,6 +121,8 @@ void SDL_Android_Init(JNIEnv* mEnv, jclass cls)
 
     midCreateGLContext = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
                                 "createGLContext","(II[I)Z");
+    midDeleteGLContext = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
+                                "deleteGLContext","()V");
     midFlipBuffers = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
                                 "flipBuffers","()V");
     midAudioInit = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
@@ -361,6 +364,13 @@ SDL_bool Android_JNI_CreateContext(int majorVersion, int minorVersion,
     return success ? SDL_TRUE : SDL_FALSE;
 }
 
+SDL_bool Android_JNI_DeleteContext(SDL_GLContext context) 
+{
+    /* There's only one context, so the parameter is ignored for now */
+    JNIEnv *env = Android_JNI_GetEnv();
+    (*env)->CallStaticBooleanMethod(env, mActivityClass, midDeleteGLContext);
+}
+
 void Android_JNI_SwapWindow()
 {
     JNIEnv *mEnv = Android_JNI_GetEnv();

src/video/android/SDL_androidgl.c

@@ -119,7 +119,9 @@ Android_GL_SwapWindow(_THIS, SDL_Window * window)
 void
 Android_GL_DeleteContext(_THIS, SDL_GLContext context)
 {
-    __android_log_print(ANDROID_LOG_INFO, "SDL", "[STUB] GL_DeleteContext\n");
+    if (context) {
+        Android_JNI_DeleteContext(context);
+    }
 }
 
 #endif /* SDL_VIDEO_DRIVER_ANDROID */