Rename "backend" headers

Working on Vulkan clarified what has always been slightly smelly about the
design and organization here: not everything that is API specific is really in
a "backend" (a PuglBackend).  The concrete example is puglGetProcAddress(),
which only makes sense for GL and is actually implemented in the "backend"
files.  Arguably puglGetContext() is also such a thing.

So, rename the headers so they can be the place where API-specific things go in
general, which happens to include a backend most of the time.  The stub is a
bit of an exception to this, but whatever.  The includes look tidier this way.

In place of the old headers are compatibility stubs that just emit a warning
and include the new version, which will be maintained for a while.

1 files changed, 53 insertions, 0 deletions

diff --git a/pugl/pugl_gl.h b/pugl/pugl_gl.h
new file mode 100644
index 0000000..7789116
--- /dev/null
+++ b/pugl/pugl_gl.h
@@ -0,0 +1,53 @@
+/*
+  Copyright 2012-2019 David Robillard <http://drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+/**
+   @file pugl_gl.h OpenGL-specific API.
+*/
+
+#ifndef PUGL_PUGL_GL_H
+#define PUGL_PUGL_GL_H
+
+#include "pugl/pugl.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+   OpenGL extension function.
+*/
+typedef void (*PuglGlFunc)(void);
+
+/**
+   Return the address of an OpenGL extension function.
+*/
+PUGL_API PuglGlFunc
+puglGetProcAddress(const char* name);
+
+/**
+   OpenGL graphics backend.
+
+   Pass the return value to puglInitBackend() to draw to a view with OpenGL.
+*/
+PUGL_API const PuglBackend*
+puglGlBackend(void);
+
+#ifdef __cplusplus
+}  /* extern "C" */
+#endif
+
+#endif // PUGL_PUGL_GL_H