EGL: default to swap interval 1

This change explicitly sets swap interval 1 on the window when an
EGLSurface is created to render to it.

Change-Id: I91eb29dbee3ae4a55076b921f084d503fbe94e03

include/gui/SurfaceTexture.h

@@ -202,6 +202,10 @@ public:
     // getCurrentScalingMode returns the scaling mode of the current buffer
     uint32_t getCurrentScalingMode() const;
 
+    // isSynchronousMode returns whether the SurfaceTexture is currently in
+    // synchronous mode.
+    bool isSynchronousMode() const;
+
     // abandon frees all the buffers and puts the SurfaceTexture into the
     // 'abandoned' state.  Once put in this state the SurfaceTexture can never
     // leave it.  When in the 'abandoned' state, all methods of the

libs/gui/SurfaceTexture.cpp

@@ -1005,6 +1005,11 @@ uint32_t SurfaceTexture::getCurrentScalingMode() const {
     return mCurrentScalingMode;
 }
 
+bool SurfaceTexture::isSynchronousMode() const {
+    Mutex::Autolock lock(mMutex);
+    return mSynchronousMode;
+}
+
 int SurfaceTexture::query(int what, int* outValue)
 {
     Mutex::Autolock lock(mMutex);

libs/gui/tests/SurfaceTexture_test.cpp

@@ -1245,6 +1245,31 @@ TEST_F(SurfaceTextureGLToGLTest, EglDestroySurfaceAfterAbandonUnrefsBuffers) {
     EXPECT_EQ(1, buffers[2]->getStrongCount());
 }
 
+TEST_F(SurfaceTextureGLToGLTest, EglSurfaceDefaultsToSynchronousMode) {
+    // This test requires 3 buffers to run on a single thread.
+    mST->setBufferCountServer(3);
+
+    ASSERT_TRUE(mST->isSynchronousMode());
+
+    for (int i = 0; i < 10; i++) {
+        // Produce a frame
+        EXPECT_TRUE(eglMakeCurrent(mEglDisplay, mProducerEglSurface,
+                mProducerEglSurface, mProducerEglContext));
+        ASSERT_EQ(EGL_SUCCESS, eglGetError());
+        glClear(GL_COLOR_BUFFER_BIT);
+        EXPECT_TRUE(eglSwapBuffers(mEglDisplay, mProducerEglSurface));
+        ASSERT_EQ(EGL_SUCCESS, eglGetError());
+
+        // Consume a frame
+        EXPECT_TRUE(eglMakeCurrent(mEglDisplay, mEglSurface, mEglSurface,
+                mEglContext));
+        ASSERT_EQ(EGL_SUCCESS, eglGetError());
+        ASSERT_EQ(NO_ERROR, mST->updateTexImage());
+    }
+
+    ASSERT_TRUE(mST->isSynchronousMode());
+}
+
 /*
  * This test fixture is for testing GL -> GL texture streaming from one thread
  * to another.  It contains functionality to create a producer thread that will

opengl/libs/EGL/eglApi.cpp

@@ -370,6 +370,11 @@ EGLSurface eglCreateWindowSurface(  EGLDisplay dpy, EGLConfig config,
             }
         }
 
+        // the EGL spec requires that a new EGLSurface default to swap interval
+        // 1, so explicitly set that on the window here.
+        ANativeWindow* anw = reinterpret_cast<ANativeWindow*>(window);
+        anw->setSwapInterval(anw, 1);
+
         EGLSurface surface = cnx->egl.eglCreateWindowSurface(
                 iDpy, iConfig, window, attrib_list);
         if (surface != EGL_NO_SURFACE) {