egl/main: Add bits for EGL_KHR_mutable_render_buffer

A follow-up patch enables EGL_KHR_mutable_render_buffer for Android.
This patch is separate from the Android patch because I think it's
easier to review the platform-independent bits separately.

Reviewed-by: Tapani Pälli <[email protected]>

1 files changed, 56 insertions, 3 deletions

diff --git a/src/egl/main/eglsurface.c b/src/egl/main/eglsurface.c
index 73c31e11588..926b7ab569a 100644
--- a/src/egl/main/eglsurface.c
+++ b/src/egl/main/eglsurface.c
@@ -123,6 +123,12 @@ _eglParseSurfaceAttribList(_EGLSurface *surf, const EGLint *attrib_list)
             break;
          }
          surf->RequestedRenderBuffer = val;
+         if (surf->Config->SurfaceType & EGL_MUTABLE_RENDER_BUFFER_BIT_KHR) {
+            /* Unlike normal EGLSurfaces, one with a mutable render buffer
+             * uses the application-chosen render buffer.
+             */
+            surf->ActiveRenderBuffer = val;
+         }
          break;
       case EGL_POST_SUB_BUFFER_SUPPORTED_NV:
          if (!dpy->Extensions.NV_post_sub_buffer ||
@@ -359,12 +365,19 @@ _eglQuerySurface(_EGLDriver *drv, _EGLDisplay *dpy, _EGLSurface *surface,
       *value = surface->SwapBehavior;
       break;
    case EGL_RENDER_BUFFER:
-      /* From the EGL 1.5 spec (2014.08.27):
+      /* From the EGL_KHR_mutable_render_buffer spec (v12):
        *
        *    Querying EGL_RENDER_BUFFER returns the buffer which client API
        *    rendering is requested to use. For a window surface, this is the
-       *    same attribute value specified when the surface was created. For
-       *    a pbuffer surface, it is always EGL_BACK_BUFFER . For a pixmap
+       *    attribute value specified when the surface was created or last set
+       *    via eglSurfaceAttrib.
+       *
+       * In other words, querying a window surface returns the value most
+       * recently *requested* by the user.
+       *
+       * The paragraph continues in the EGL 1.5 spec (2014.08.27):
+       *
+       *    For a pbuffer surface, it is always EGL_BACK_BUFFER . For a pixmap
        *    surface, it is always EGL_SINGLE_BUFFER . To determine the actual
        *    buffer being rendered to by a context, call eglQueryContext.
        */
@@ -472,6 +485,31 @@ _eglSurfaceAttrib(_EGLDriver *drv, _EGLDisplay *dpy, _EGLSurface *surface,
          break;
       surface->MultisampleResolve = value;
       break;
+   case EGL_RENDER_BUFFER:
+      if (!dpy->Extensions.KHR_mutable_render_buffer) {
+         err = EGL_BAD_ATTRIBUTE;
+         break;
+      }
+
+      if (value != EGL_BACK_BUFFER && value != EGL_SINGLE_BUFFER) {
+         err = EGL_BAD_PARAMETER;
+         break;
+      }
+
+      /* From the EGL_KHR_mutable_render_buffer spec (v12):
+       *
+       *    If attribute is EGL_RENDER_BUFFER, and the EGL_SURFACE_TYPE
+       *    attribute of the EGLConfig used to create surface does not contain
+       *    EGL_MUTABLE_RENDER_BUFFER_BIT_KHR, [...] an EGL_BAD_MATCH error is
+       *    generated [...].
+       */
+      if (!(surface->Config->SurfaceType & EGL_MUTABLE_RENDER_BUFFER_BIT_KHR)) {
+         err = EGL_BAD_MATCH;
+         break;
+      }
+
+      surface->RequestedRenderBuffer = value;
+      break;
    case EGL_SWAP_BEHAVIOR:
       switch (value) {
       case EGL_BUFFER_DESTROYED:
@@ -573,3 +611,18 @@ _eglSwapInterval(_EGLDriver *drv, _EGLDisplay *dpy, _EGLSurface *surf,
 {
    return EGL_TRUE;
 }
+
+EGLBoolean
+_eglSurfaceHasMutableRenderBuffer(_EGLSurface *surf)
+{
+   return surf->Type == EGL_WINDOW_BIT &&
+          surf->Config &&
+          (surf->Config->SurfaceType & EGL_MUTABLE_RENDER_BUFFER_BIT_KHR);
+}
+
+EGLBoolean
+_eglSurfaceInSharedBufferMode(_EGLSurface *surf)
+{
+   return _eglSurfaceHasMutableRenderBuffer(surf) &&
+          surf->ActiveRenderBuffer == EGL_SINGLE_BUFFER;
+}