direct-to-native-GL for GLX clients on Cygwin ("Windows-DRI")

Structurally, this is very similar to the existing Apple-DRI code, except I
have chosen to implement this using the __GLXDRIdisplay, etc. vtables (as
suggested originally in [1]), rather than a maze of ifdefs.  This also means
that LIBGL_ALWAYS_SOFTWARE and LIBGL_ALWAYS_INDIRECT work as expected.

[1] https://lists.freedesktop.org/archives/mesa-dev/2010-May/000756.html

This adds:

* the Windows-DRI extension protocol headers and the windowsdriproto.pc
file, for use in building the Windows-DRI extension for the X server

* a Windows-DRI extension helper client library

* a Windows-specific DRI implementation for GLX clients

The server is queried for Windows-DRI extension support on the screen before
using it (to detect the case where WGL is disabled or can't be activated).

The server is queried for fbconfigID to pixelformatindex mapping, which is
used to augment glx_config.

The server is queried for a native handle for the drawable (which is of a
different type for windows, pixmaps and pbuffers), which is used to augment
__GLXDRIdrawable.

Various GLX extensions are enabled depending on if the equivalent WGL
extension is available.

1 files changed, 108 insertions, 0 deletions

diff --git a/src/glx/windows/wgl.c b/src/glx/windows/wgl.c
new file mode 100644
index 00000000000..ffc97675072
--- /dev/null
+++ b/src/glx/windows/wgl.c
@@ -0,0 +1,108 @@
+/*
+ * Copyright © 2014 Jon Turney
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/*
+  Wrapper functions for calling WGL extension functions
+ */
+
+#include "wgl.h"
+
+#include <stdio.h>
+
+#define RESOLVE_DECL(type) \
+    static type type##proc = NULL;
+
+#define PRERESOLVE(type, symbol) \
+    type##proc = (type)wglGetProcAddress(symbol); \
+    if (type##proc == NULL) \
+       printf("Can't resolve \"%s\"\n", symbol);
+
+#define CHECK_RESOLVED(type, retval) \
+  if (type##proc == NULL) { \
+    return retval; \
+  }
+
+#define RESOLVED_PROC(type) type##proc
+
+RESOLVE_DECL(PFNWGLGETEXTENSIONSSTRINGARBPROC);
+RESOLVE_DECL(PFNWGLCREATECONTEXTATTRIBSARBPROC);
+RESOLVE_DECL(PFNWGLMAKECONTEXTCURRENTARBPROC);
+RESOLVE_DECL(PFNWGLCREATEPBUFFERARBPROC);
+RESOLVE_DECL(PFNWGLGETPBUFFERDCARBPROC);
+RESOLVE_DECL(PFNWGLRELEASEPBUFFERDCARBPROC);
+RESOLVE_DECL(PFNWGLDESTROYPBUFFERARBPROC);
+
+void wglResolveExtensionProcs(void)
+{
+  PRERESOLVE(PFNWGLGETEXTENSIONSSTRINGARBPROC, "wglGetExtensionsStringARB");
+  PRERESOLVE(PFNWGLCREATECONTEXTATTRIBSARBPROC, "wglCreateContextAttribsARB");
+  PRERESOLVE(PFNWGLMAKECONTEXTCURRENTARBPROC, "wglMakeContextCurrentARB");
+  PRERESOLVE(PFNWGLCREATEPBUFFERARBPROC, "wglCreatePbufferARB");
+  PRERESOLVE(PFNWGLGETPBUFFERDCARBPROC, "wglGetPbufferDCARB");
+  PRERESOLVE(PFNWGLRELEASEPBUFFERDCARBPROC, "wglReleasePbufferDCARB");
+  PRERESOLVE(PFNWGLDESTROYPBUFFERARBPROC, "wglDestroyPbufferARB");
+}
+
+const char *wglGetExtensionsStringARB(HDC hdc_)
+{
+   CHECK_RESOLVED(PFNWGLGETEXTENSIONSSTRINGARBPROC, "");
+   return RESOLVED_PROC(PFNWGLGETEXTENSIONSSTRINGARBPROC)(hdc_);
+}
+
+HGLRC wglCreateContextAttribsARB(HDC hdc_, HGLRC hShareContext_,
+                                     const int *attribList_)
+{
+   CHECK_RESOLVED(PFNWGLCREATECONTEXTATTRIBSARBPROC, NULL);
+   return RESOLVED_PROC(PFNWGLCREATECONTEXTATTRIBSARBPROC)(hdc_, hShareContext_, attribList_);
+}
+
+BOOL wglMakeContextCurrentARB(HDC hDrawDC_, HDC hReadDC_, HGLRC hglrc_)
+{
+   CHECK_RESOLVED(PFNWGLMAKECONTEXTCURRENTARBPROC, FALSE);
+   return RESOLVED_PROC(PFNWGLMAKECONTEXTCURRENTARBPROC)(hDrawDC_, hReadDC_, hglrc_);
+}
+
+HPBUFFERARB wglCreatePbufferARB(HDC hDC_, int iPixelFormat_, int iWidth_,
+                                int iHeight_, const int *piAttribList_)
+{
+   CHECK_RESOLVED(PFNWGLCREATEPBUFFERARBPROC, NULL);
+   return RESOLVED_PROC(PFNWGLCREATEPBUFFERARBPROC)(hDC_, iPixelFormat_, iWidth_, iHeight_, piAttribList_);
+}
+
+HDC wglGetPbufferDCARB(HPBUFFERARB hPbuffer_)
+{
+   CHECK_RESOLVED(PFNWGLGETPBUFFERDCARBPROC, NULL);
+   return RESOLVED_PROC(PFNWGLGETPBUFFERDCARBPROC)(hPbuffer_);
+}
+
+int wglReleasePbufferDCARB(HPBUFFERARB hPbuffer_, HDC hDC_)
+{
+   CHECK_RESOLVED(PFNWGLRELEASEPBUFFERDCARBPROC, 0)
+   return RESOLVED_PROC(PFNWGLRELEASEPBUFFERDCARBPROC)(hPbuffer_, hDC_);
+}
+
+BOOL wglDestroyPbufferARB(HPBUFFERARB hPbuffer_)
+{
+   CHECK_RESOLVED(PFNWGLDESTROYPBUFFERARBPROC, FALSE);
+   return RESOLVED_PROC(PFNWGLDESTROYPBUFFERARBPROC)(hPbuffer_);
+}