[gtk/wip/master.win.egl: 17/20] build: Check for EGL support in libepoxy on Windows

[Chun-wei Fan <fanchunwei src gnome org>]

commit 6eeef2b1e5f7a0e2845d777b3c31ad1939c1128d
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Fri Jun 22 15:02:24 2018 +0800

    build: Check for EGL support in libepoxy on Windows
    
    ...EGL support needs to be explicitly enabled during the build of
    libepoxy on Windows as it is not enabled by default on Windows.
    
    With this, we can add an EGL renderer for Windows that make use of
    Google's libANGLE, which is a library that translates OpenGL/ES calls
    to Direct3D 9/11, which will provide better hardware compatibility
    on Windows and would act as one of the foundations to resolve issue #105.

 gdk/win32/meson.build |  8 +++++++-
 meson.build           | 16 ++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)
---
diff --git a/gdk/win32/meson.build b/gdk/win32/meson.build
index 9567c96609..cd1c36ce5d 100644
--- a/gdk/win32/meson.build
+++ b/gdk/win32/meson.build
@@ -43,6 +43,12 @@ gdk_win32_public_headers = files([
 
 install_headers(gdk_win32_public_headers, 'gdkwin32.h', subdir: 'gtk-4.0/gdk/win32/')
 
+GDK_WIN32_EGL_CFLAGS = []
+
+if win32_has_egl
+  GDK_WIN32_EGL_CFLAGS = ['-DGDK_WIN32_ENABLE_EGL']
+endif
+
 gdk_win32_deps = [ # FIXME
     pangowin32_dep
 ]
@@ -50,5 +56,5 @@ gdk_win32_deps = [ # FIXME
 libgdk_win32 = static_library('gdk-win32',
   gdk_win32_sources, gdkconfig, gdkenum_h,
   include_directories: [confinc, gdkinc],
-  c_args: ['-DGDK_COMPILATION', '-DG_LOG_DOMAIN="Gdk"', '-DINSIDE_GDK_WIN32'],
+  c_args: ['-DGDK_COMPILATION', '-DG_LOG_DOMAIN="Gdk"', '-DINSIDE_GDK_WIN32'] + GDK_WIN32_EGL_CFLAGS,
   dependencies: [gdk_deps, gdk_win32_deps])
diff --git a/meson.build b/meson.build
index c07ae0340e..2a5f57565c 100644
--- a/meson.build
+++ b/meson.build
@@ -573,6 +573,22 @@ if win32_enabled
   endif
   pc_gdk_extra_libs += ['-lwinmm', '-ldwmapi', '-lsetupapi', '-lcfgmgr32']
   backend_immodules += ['ime']
+
+  # Check whether libepoxy is built with EGL support on Windows
+  win32_has_egl = cc.links(
+     '''
+     #include <epoxy/egl.h>
+        
+     int main(int argc, char *argv[])
+     {
+       EGLDisplay disp = EGL_NO_DISPLAY;
+
+       return epoxy_egl_version (disp);
+     } 
+     ''',
+     dependencies : epoxy_dep,
+     name : 'libepoxy supports EGL on Windows'
+    )
 endif
 
 # Check for bind_textdomain_codeset, including -lintl if GLib brings it in by