wayland: Add an extension to create wl_buffers from EGLImages

This adds an extension called EGL_WL_create_wayland_buffer_from_image
which adds the following single function:

struct wl_buffer *
eglCreateWaylandBufferFromImageWL(EGLDisplay dpy, EGLImageKHR image);

The function creates a wl_buffer which shares its contents with the given
EGLImage. The expected use case for this is in a nested Wayland compositor
which is using subsurfaces to present buffers from its clients. Using this
extension it can attach the client buffers directly to the subsurface without
having to blit the contents into an intermediate buffer. The compositing can
then be done in the parent compositor.

The extension is only implemented in the Wayland EGL platform because of
course it wouldn't make sense anywhere else.

4 files changed, 35 insertions, 0 deletions

diff --git a/src/egl/main/eglapi.c b/src/egl/main/eglapi.c
index 66f96de4140..9ac2ef44698 100644
--- a/src/egl/main/eglapi.c
+++ b/src/egl/main/eglapi.c
@@ -973,6 +973,9 @@ eglGetProcAddress(const char *procname)
       { "eglUnbindWaylandDisplayWL", (_EGLProc) eglUnbindWaylandDisplayWL },
       { "eglQueryWaylandBufferWL", (_EGLProc) eglQueryWaylandBufferWL },
 #endif
+#ifdef EGL_WL_create_wayland_buffer_from_image
+      { "eglCreateWaylandBufferFromImageWL", (_EGLProc) eglCreateWaylandBufferFromImageWL },
+#endif
       { "eglPostSubBufferNV", (_EGLProc) eglPostSubBufferNV },
 #ifdef EGL_EXT_swap_buffers_with_damage
       { "eglSwapBuffersWithDamageEXT", (_EGLProc) eglSwapBuffersWithDamageEXT },
@@ -1601,6 +1604,28 @@ eglQueryWaylandBufferWL(EGLDisplay dpy, struct wl_resource *buffer,
 }
 #endif
 
+#ifdef EGL_WL_create_wayland_buffer_from_image
+struct wl_buffer * EGLAPIENTRY
+eglCreateWaylandBufferFromImageWL(EGLDisplay dpy, EGLImageKHR image)
+{
+   _EGLDisplay *disp = _eglLockDisplay(dpy);
+   _EGLImage *img;
+   _EGLDriver *drv;
+   struct wl_buffer *ret;
+
+   _EGL_CHECK_DISPLAY(disp, NULL, drv);
+   assert(disp->Extensions.WL_create_wayland_buffer_from_image);
+
+   img = _eglLookupImage(image, disp);
+
+   if (!img)
+      RETURN_EGL_ERROR(disp, EGL_BAD_PARAMETER, NULL);
+
+   ret = drv->API.CreateWaylandBufferFromImageWL(drv, disp, img);
+
+   RETURN_EGL_EVAL(disp, ret);
+}
+#endif
 
 EGLBoolean EGLAPIENTRY
 eglPostSubBufferNV(EGLDisplay dpy, EGLSurface surface,
diff --git a/src/egl/main/eglapi.h b/src/egl/main/eglapi.h
index 4a4f9765219..05803449a2e 100644
--- a/src/egl/main/eglapi.h
+++ b/src/egl/main/eglapi.h
@@ -126,6 +126,10 @@ typedef EGLBoolean (*UnbindWaylandDisplayWL_t)(_EGLDriver *drv, _EGLDisplay *dis
 typedef EGLBoolean (*QueryWaylandBufferWL_t)(_EGLDriver *drv, _EGLDisplay *displ, struct wl_resource *buffer, EGLint attribute, EGLint *value);
 #endif
 
+#ifdef EGL_WL_create_wayland_buffer_from_image
+typedef struct wl_buffer * (*CreateWaylandBufferFromImageWL_t)(_EGLDriver *drv, _EGLDisplay *disp, _EGLImage *img);
+#endif
+
 typedef EGLBoolean (*PostSubBufferNV_t)(_EGLDriver *drv, _EGLDisplay *disp, _EGLSurface *surface, EGLint x, EGLint y, EGLint width, EGLint height);
 
 typedef EGLint (*QueryBufferAge_t)(_EGLDriver *drv,
@@ -210,6 +214,10 @@ struct _egl_api
    QueryWaylandBufferWL_t QueryWaylandBufferWL;
 #endif
 
+#ifdef EGL_WL_create_wayland_buffer_from_image
+   CreateWaylandBufferFromImageWL_t CreateWaylandBufferFromImageWL;
+#endif
+
 #ifdef EGL_EXT_swap_buffers_with_damage
    SwapBuffersWithDamageEXT_t SwapBuffersWithDamageEXT;
 #endif /* EGL_EXT_swap_buffers_with_damage */
diff --git a/src/egl/main/egldisplay.h b/src/egl/main/egldisplay.h
index fefd19c47b2..b95b2f79852 100644
--- a/src/egl/main/egldisplay.h
+++ b/src/egl/main/egldisplay.h
@@ -91,6 +91,7 @@ struct _egl_extensions
    EGLBoolean MESA_drm_image;
 
    EGLBoolean WL_bind_wayland_display;
+   EGLBoolean WL_create_wayland_buffer_from_image;
 
    EGLBoolean KHR_image_base;
    EGLBoolean KHR_image_pixmap;
diff --git a/src/egl/main/eglmisc.c b/src/egl/main/eglmisc.c
index 2decc1b778d..cff61669dc8 100644
--- a/src/egl/main/eglmisc.c
+++ b/src/egl/main/eglmisc.c
@@ -92,6 +92,7 @@ _eglUpdateExtensionsString(_EGLDisplay *dpy)
    _EGL_CHECK_EXTENSION(MESA_drm_image);
 
    _EGL_CHECK_EXTENSION(WL_bind_wayland_display);
+   _EGL_CHECK_EXTENSION(WL_create_wayland_buffer_from_image);
 
    _EGL_CHECK_EXTENSION(KHR_image_base);
    _EGL_CHECK_EXTENSION(KHR_image_pixmap);