Add initial prototype.

3-mid/opengl/source/platform/egl/opengl-surface.adb

@@ -0,0 +1,58 @@
+with
+     opengl.surface_Profile.privvy,
+     opengl.Display        .privvy,
+
+     eGL.Binding,
+     interfaces.c.Strings,
+     System;
+
+
+package body opengl.Surface
+is
+   use eGL.Binding;
+
+
+   --  Forge
+   --
+   procedure define (Self : in out Item;   surface_Profile : in opengl.surface_Profile.item'Class;
+                                           Display         : in opengl.Display.Item;
+                                           Window_Id       : in Natural)
+   is
+      use opengl.Display        .privvy,
+          opengl.surface_Profile.privvy,
+          System;
+   begin
+      Self.egl_Surface := eglCreateWindowSurface (to_eGL (Display),
+                                                  to_eGL (surface_Profile),
+                                                  egl.NativeWindowType (Window_Id),
+                                                  null); -- const EGLint *attribList);
+
+      if self.egl_Surface = EGL_NO_SURFACE then
+         raise opengl.Error with "unable to create an EGL surface for a window";
+      end if;
+
+      Self.Display := Display;
+   end define;
+
+
+
+
+   --  Operations
+   --
+   procedure swap_Buffers (Self : in Item)
+   is
+      use      openGL.Display.privvy,
+               eGL;
+      use type EGLBoolean;
+
+      Success : egl.EGLBoolean;
+   begin
+      Success := eglSwapBuffers (to_eGL (Self.Display),
+                                 Self.egl_Surface);
+      if Success = EGL_FALSE then
+         raise opengl.Error with "unable to swap egl buffers";
+      end if;
+   end swap_Buffers;
+
+
+end opengl.Surface;