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, 403 insertions, 0 deletions

diff --git a/src/glx/windows/windowsgl.c b/src/glx/windows/windowsgl.c
new file mode 100644
index 00000000000..56849da8371
--- /dev/null
+++ b/src/glx/windows/windowsgl.c
@@ -0,0 +1,403 @@
+/*
+ * 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.
+ */
+
+#include "windowsgl.h"
+#include "windowsgl_internal.h"
+
+#include "glapi.h"
+#include "wgl.h"
+
+#include <dlfcn.h>
+#include <assert.h>
+#include <stdio.h>
+#include <strings.h>
+
+static struct _glapi_table *windows_api = NULL;
+
+static void *
+windows_get_dl_handle(void)
+{
+   static void *dl_handle = NULL;
+
+   if (!dl_handle)
+      dl_handle = dlopen("cygnativeGLthunk.dll", RTLD_NOW);
+
+   return dl_handle;
+}
+
+static void
+windows_glapi_create_table(void)
+{
+   if (windows_api)
+      return;
+
+   windows_api = _glapi_create_table_from_handle(windows_get_dl_handle(), "gl");
+   assert(windows_api);
+}
+
+static void windows_glapi_set_dispatch(void)
+{
+   windows_glapi_create_table();
+   _glapi_set_dispatch(windows_api);
+}
+
+windowsContext *
+windows_create_context(int pxfi, windowsContext *shared)
+{
+   windowsContext *gc;
+
+   gc = calloc(1, sizeof *gc);
+   if (gc == NULL)
+      return NULL;
+
+   // create a temporary, invisible window
+#define GL_TEMP_WINDOW_CLASS "glTempWndClass"
+   {
+      static wATOM glTempWndClass = 0;
+
+      if (glTempWndClass == 0) {
+         WNDCLASSEX wc;
+         wc.cbSize = sizeof(WNDCLASSEX);
+         wc.style = CS_HREDRAW | CS_VREDRAW;
+         wc.lpfnWndProc = DefWindowProc;
+         wc.cbClsExtra = 0;
+         wc.cbWndExtra = 0;
+         wc.hInstance = GetModuleHandle(NULL);
+         wc.hIcon = 0;
+         wc.hCursor = 0;
+         wc.hbrBackground = (HBRUSH) GetStockObject(WHITE_BRUSH);
+         wc.lpszMenuName = NULL;
+         wc.lpszClassName = GL_TEMP_WINDOW_CLASS;
+         wc.hIconSm = 0;
+         RegisterClassEx(&wc);
+      }
+   }
+
+   HWND hwnd = CreateWindowExA(0,
+                               GL_TEMP_WINDOW_CLASS,
+                               "glWindow",
+                               0,
+                               0, 0, 0, 0,
+                               NULL, NULL, GetModuleHandle(NULL), NULL);
+   HDC hdc = GetDC(hwnd);
+
+   // We must set the windows pixel format before we can create a WGL context
+   gc->pxfi = pxfi;
+   SetPixelFormat(hdc, gc->pxfi, NULL);
+
+   gc->ctx = wglCreateContext(hdc);
+
+   if (shared && gc->ctx)
+      wglShareLists(shared->ctx, gc->ctx);
+
+   ReleaseDC(hwnd, hdc);
+   DestroyWindow(hwnd);
+
+   if (!gc->ctx)
+   {
+     free(gc);
+     return NULL;
+   }
+
+   return gc;
+}
+
+windowsContext *
+windows_create_context_attribs(int pxfi, windowsContext *shared, const int *attribList)
+{
+   windowsContext *gc;
+
+   gc = calloc(1, sizeof *gc);
+   if (gc == NULL)
+      return NULL;
+
+   // create a temporary, invisible window
+#define GL_TEMP_WINDOW_CLASS "glTempWndClass"
+   {
+      static wATOM glTempWndClass = 0;
+
+      if (glTempWndClass == 0) {
+         WNDCLASSEX wc;
+         wc.cbSize = sizeof(WNDCLASSEX);
+         wc.style = CS_HREDRAW | CS_VREDRAW;
+         wc.lpfnWndProc = DefWindowProc;
+         wc.cbClsExtra = 0;
+         wc.cbWndExtra = 0;
+         wc.hInstance = GetModuleHandle(NULL);
+         wc.hIcon = 0;
+         wc.hCursor = 0;
+         wc.hbrBackground = (HBRUSH) GetStockObject(WHITE_BRUSH);
+         wc.lpszMenuName = NULL;
+         wc.lpszClassName = GL_TEMP_WINDOW_CLASS;
+         wc.hIconSm = 0;
+         RegisterClassEx(&wc);
+      }
+   }
+
+   HWND hwnd = CreateWindowExA(0,
+                               GL_TEMP_WINDOW_CLASS,
+                               "glWindow",
+                               0,
+                               0, 0, 0, 0,
+                               NULL, NULL, GetModuleHandle(NULL), NULL);
+   HDC hdc = GetDC(hwnd);
+   HGLRC shareContext = NULL;
+   if (shared)
+      shareContext = shared->ctx;
+
+   // We must set the windows pixel format before we can create a WGL context
+   gc->pxfi = pxfi;
+   SetPixelFormat(hdc, gc->pxfi, NULL);
+
+   gc->ctx = wglCreateContextAttribsARB(hdc, shareContext, attribList);
+
+   ReleaseDC(hwnd, hdc);
+   DestroyWindow(hwnd);
+
+   if (!gc->ctx)
+   {
+     free(gc);
+     return NULL;
+   }
+
+   return gc;
+}
+
+void
+windows_destroy_context(windowsContext *context)
+{
+   wglDeleteContext(context->ctx);
+   context->ctx = NULL;
+   free(context);
+}
+
+int windows_bind_context(windowsContext *context, windowsDrawable *draw, windowsDrawable *read)
+{
+   HDC drawDc = draw->callbacks->getdc(draw);
+
+   if (!draw->pxfi)
+   {
+      SetPixelFormat(drawDc, context->pxfi, NULL);
+      draw->pxfi = context->pxfi;
+   }
+
+   if ((read != NULL) &&  (read != draw))
+   {
+      /*
+        If there is a separate read drawable, create a separate read DC, and
+        use the wglMakeContextCurrent extension to make the context current
+        drawing to one DC and reading from the other
+
+        Should only occur when WGL_ARB_make_current_read extension is present
+      */
+      HDC readDc = read->callbacks->getdc(read);
+
+      BOOL ret = wglMakeContextCurrentARB(drawDc, readDc, context->ctx);
+
+      read->callbacks->releasedc(read, readDc);
+
+      if (!ret) {
+         printf("wglMakeContextCurrentARB error: %08x\n", GetLastError());
+         return FALSE;
+      }
+   }
+   else
+   {
+      /* Otherwise, just use wglMakeCurrent */
+      BOOL ret = wglMakeCurrent(drawDc, context->ctx);
+      if (!ret) {
+         printf("wglMakeCurrent error: %08x\n", GetLastError());
+         return FALSE;
+      }
+   }
+
+   draw->callbacks->releasedc(draw, drawDc);
+
+   windows_glapi_set_dispatch();
+
+   return TRUE;
+}
+
+void windows_unbind_context(windowsContext * context)
+{
+   wglMakeCurrent(NULL, NULL);
+}
+
+/*
+ *
+ */
+
+void
+windows_swap_buffers(windowsDrawable *draw)
+{
+   HDC drawDc = GetDC(draw->hWnd);
+   SwapBuffers(drawDc);
+   ReleaseDC(draw->hWnd, drawDc);
+}
+
+
+typedef void (__stdcall * PFNGLADDSWAPHINTRECTWIN) (GLint x, GLint y,
+                                                    GLsizei width,
+                                                    GLsizei height);
+
+static void
+glAddSwapHintRectWIN(GLint x, GLint y, GLsizei width,
+                            GLsizei height)
+{
+   PFNGLADDSWAPHINTRECTWIN proc = (PFNGLADDSWAPHINTRECTWIN)wglGetProcAddress("glAddSwapHintRectWIN");
+   if (proc)
+      proc(x, y, width, height);
+}
+
+void
+windows_copy_subbuffer(windowsDrawable *draw,
+                      int x, int y, int width, int height)
+{
+   glAddSwapHintRectWIN(x, y, width, height);
+   windows_swap_buffers(draw);
+}
+
+/*
+ * Helper function for calling a test function on an initial context
+ */
+static void
+windows_call_with_context(void (*proc)(HDC, void *), void *args)
+{
+   // create window class
+#define WIN_GL_TEST_WINDOW_CLASS "GLTest"
+   {
+      static wATOM glTestWndClass = 0;
+
+      if (glTestWndClass == 0) {
+         WNDCLASSEX wc;
+
+         wc.cbSize = sizeof(WNDCLASSEX);
+         wc.style = CS_HREDRAW | CS_VREDRAW;
+         wc.lpfnWndProc = DefWindowProc;
+         wc.cbClsExtra = 0;
+         wc.cbWndExtra = 0;
+         wc.hInstance = GetModuleHandle(NULL);
+         wc.hIcon = 0;
+         wc.hCursor = 0;
+         wc.hbrBackground = (HBRUSH) GetStockObject(WHITE_BRUSH);
+         wc.lpszMenuName = NULL;
+         wc.lpszClassName = WIN_GL_TEST_WINDOW_CLASS;
+         wc.hIconSm = 0;
+         glTestWndClass = RegisterClassEx(&wc);
+      }
+   }
+
+   // create an invisible window for a scratch DC
+   HWND hwnd = CreateWindowExA(0,
+                               WIN_GL_TEST_WINDOW_CLASS,
+                               "GL Renderer Capabilities Test Window",
+                               0, 0, 0, 0, 0, NULL, NULL, GetModuleHandle(NULL),
+                               NULL);
+   if (hwnd) {
+      HDC hdc = GetDC(hwnd);
+
+      // we must set a pixel format before we can create a context, just use the first one...
+      SetPixelFormat(hdc, 1, NULL);
+      HGLRC hglrc = wglCreateContext(hdc);
+      wglMakeCurrent(hdc, hglrc);
+
+      // call the test function
+      proc(hdc, args);
+
+      // clean up
+      wglMakeCurrent(NULL, NULL);
+      wglDeleteContext(hglrc);
+      ReleaseDC(hwnd, hdc);
+      DestroyWindow(hwnd);
+   }
+}
+
+static void
+windows_check_render_test(HDC hdc, void *args)
+{
+   int *result = (int *)args;
+
+   /* Rather than play linkage games using stdcall to ensure we get
+      glGetString from opengl32.dll here, use dlsym */
+   void *dlhandle = windows_get_dl_handle();
+   const char *(*proc)(int) = dlsym(dlhandle, "glGetString");
+   const char *gl_renderer = (const char *)proc(GL_RENDERER);
+
+   if ((!gl_renderer) || (strcasecmp(gl_renderer, "GDI Generic") == 0))
+      *result = FALSE;
+   else
+      *result = TRUE;
+}
+
+int
+windows_check_renderer(void)
+{
+   int result;
+   windows_call_with_context(windows_check_render_test, &result);
+   return result;
+}
+
+typedef struct {
+   char *gl_extensions;
+   char *wgl_extensions;
+} windows_extensions_result;
+
+static void
+windows_extensions_test(HDC hdc, void *args)
+{
+   windows_extensions_result *r = (windows_extensions_result *)args;
+
+   void *dlhandle = windows_get_dl_handle();
+   const char *(*proc)(int) = dlsym(dlhandle, "glGetString");
+
+   r->gl_extensions = strdup(proc(GL_EXTENSIONS));
+
+   wglResolveExtensionProcs();
+   r->wgl_extensions = strdup(wglGetExtensionsStringARB(hdc));
+}
+
+void
+windows_extensions(char **gl_extensions, char **wgl_extensions)
+{
+   windows_extensions_result result;
+
+   *gl_extensions = "";
+   *wgl_extensions = "";
+
+   windows_call_with_context(windows_extensions_test, &result);
+
+   *gl_extensions = result.gl_extensions;
+   *wgl_extensions = result.wgl_extensions;
+}
+
+void windows_setTexBuffer(windowsContext *context, int textureTarget,
+                         int textureFormat, windowsDrawable *drawable)
+{
+   // not yet implemented
+}
+
+void windows_releaseTexBuffer(windowsContext *context, int textureTarget,
+                             windowsDrawable *drawable)
+{
+   // not yet implemented
+}