eglglessink: Make the context current for the thread and unbind it again around every use

This fixes some crashes and leaking of our context into other
OpenGL code on the same thread.

ext/eglgles/gsteglglessink.c

@@ -376,6 +376,7 @@ static inline gboolean got_gl_error (const char *wtf);
 static inline void show_egl_error (const char *wtf);
 static void gst_eglglessink_wipe_fmt (gpointer data);
 static inline gboolean egl_init (GstEglGlesSink * eglglessink);
+static gboolean gst_eglglessink_context_make_current (GstEglGlesSink * eglglessink, gboolean bind);
 
 static GstBufferClass *gsteglglessink_buffer_parent_class = NULL;
 #define GST_TYPE_EGLGLESBUFFER (gst_eglglesbuffer_get_type())
@@ -1041,6 +1042,9 @@ gst_eglglessink_stop (GstBaseSink * sink)
 
   /* EGL/GLES2 cleanup */
 
+  if (!gst_eglglessink_context_make_current (eglglessink, TRUE))
+    return FALSE;
+
   if (eglglessink->rendering_path == GST_EGLGLESSINK_RENDER_SLOW) {
     glUseProgram (0);
 
@@ -1070,6 +1074,9 @@ gst_eglglessink_stop (GstBaseSink * sink)
     }
   }
 
+  if (!gst_eglglessink_context_make_current (eglglessink, FALSE))
+    return FALSE;
+
   if (eglglessink->eglglesctx->surface) {
     eglDestroySurface (eglglessink->eglglesctx->display,
         eglglessink->eglglesctx->surface);
@@ -1433,6 +1440,32 @@ gst_eglglessink_update_surface_dimensions (GstEglGlesSink * eglglessink)
   return FALSE;
 }
 
+static gboolean
+gst_eglglessink_context_make_current (GstEglGlesSink * eglglessink, gboolean bind)
+{
+  g_assert (eglglessink->eglglesctx->display != NULL);
+
+  if (bind && eglglessink->eglglesctx->surface && eglglessink->eglglesctx->eglcontext) {
+    if (!eglMakeCurrent (eglglessink->eglglesctx->display,
+            eglglessink->eglglesctx->surface, eglglessink->eglglesctx->surface,
+            eglglessink->eglglesctx->eglcontext)) {
+      show_egl_error ("eglMakeCurrent");
+      GST_ERROR_OBJECT (eglglessink, "Couldn't bind context");
+      return FALSE;
+    }
+  } else {
+    if (!eglMakeCurrent (eglglessink->eglglesctx->display,
+            EGL_NO_SURFACE, EGL_NO_SURFACE,
+            EGL_NO_CONTEXT)) {
+      show_egl_error ("eglMakeCurrent");
+      GST_ERROR_OBJECT (eglglessink, "Couldn't unbind context");
+      return FALSE;
+    }
+  }
+
+  return TRUE;
+}
+
 static gboolean
 gst_eglglessink_init_egl_surface (GstEglGlesSink * eglglessink)
 {
@@ -1457,13 +1490,8 @@ gst_eglglessink_init_egl_surface (GstEglGlesSink * eglglessink)
     goto HANDLE_EGL_ERROR_LOCKED;
   }
 
-  if (!eglMakeCurrent (eglglessink->eglglesctx->display,
+  if (!gst_eglglessink_context_make_current (eglglessink, TRUE))
-          eglglessink->eglglesctx->surface, eglglessink->eglglesctx->surface,
-          eglglessink->eglglesctx->eglcontext)) {
-    show_egl_error ("eglCreateWindowSurface");
-    GST_ERROR_OBJECT (eglglessink, "Couldn't bind surface/context");
     goto HANDLE_EGL_ERROR_LOCKED;
-  }
 
   /* Save surface dims */
   gst_eglglessink_update_surface_dimensions (eglglessink);
@@ -1864,6 +1892,9 @@ gst_eglglessink_render_and_display (GstEglGlesSink * eglglessink,
   };
 #endif
 
+  if (!gst_eglglessink_context_make_current (eglglessink, TRUE))
+    goto HANDLE_EGL_ERROR;
+
   w = GST_VIDEO_SINK_WIDTH (eglglessink);
   h = GST_VIDEO_SINK_HEIGHT (eglglessink);
 
@@ -2101,6 +2132,9 @@ gst_eglglessink_render_and_display (GstEglGlesSink * eglglessink,
       }
   }
 
+  if (!gst_eglglessink_context_make_current (eglglessink, FALSE))
+    goto HANDLE_EGL_ERROR;
+
   GST_DEBUG_OBJECT (eglglessink, "Succesfully rendered 1 frame");
   return GST_FLOW_OK;
 
@@ -2108,6 +2142,8 @@ HANDLE_EGL_ERROR:
   GST_ERROR_OBJECT (eglglessink, "EGL call returned error %x", eglGetError ());
 HANDLE_ERROR:
   GST_ERROR_OBJECT (eglglessink, "Rendering disabled for this frame");
+
+  gst_eglglessink_context_make_current (eglglessink, FALSE);
   return GST_FLOW_ERROR;
 }
 
@@ -2304,6 +2340,9 @@ gst_eglglessink_setcaps (GstBaseSink * bsink, GstCaps * caps)
     }
   }
 
+  if (!gst_eglglessink_context_make_current (eglglessink, FALSE))
+    return FALSE;
+
 SUCCEED:
   GST_INFO_OBJECT (eglglessink, "Setcaps succeed");
   return TRUE;
@@ -2311,6 +2350,7 @@ SUCCEED:
 /* Errors */
 HANDLE_ERROR:
   GST_ERROR_OBJECT (eglglessink, "Setcaps failed");
+  gst_eglglessink_context_make_current (eglglessink, FALSE);
   return FALSE;
 }