[gtk/backport-font-feature-pango-hb: 7/7] Visual Studio projects: Update README for additional features

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

commit 6ae742537c223b700e9c1c4c334d4ff1a6e6eba8
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Fri Nov 26 16:04:32 2021 +0800

    Visual Studio projects: Update README for additional features
    
    Rename README_EGL_MSVC.txt to README_FEATURES_MSVC.txt, as we now have
    more features that can be included in the builds using the Visual
    Studio projects, which require additional depedencies and manual
    enabling.
    
    Specifically, this outlines how the font tweaking feature in libgtk can
    be enabled and for people who wish to do so, how to enable the Font
    Features demo in gtk3-demo.exe.

 win32/Makefile.am              |  2 +-
 win32/README_EGL_MSVC.txt      | 29 -----------------
 win32/README_FEATURES_MSVC.txt | 72 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 73 insertions(+), 30 deletions(-)
---
diff --git a/win32/Makefile.am b/win32/Makefile.am
index 31c8715269..e5f9a3ff73 100644
--- a/win32/Makefile.am
+++ b/win32/Makefile.am
@@ -49,7 +49,7 @@ EXTRA_DIST += \
        replace.py                      \
        pc_base.py                      \
        gtkpc.py                        \
-       README_EGL_MSVC.txt             \
+       README_FEATURES_MSVC.txt        \
        $(GENERATED_ITEMS)
 
 -include $(top_srcdir)/git.mk
diff --git a/win32/README_FEATURES_MSVC.txt b/win32/README_FEATURES_MSVC.txt
new file mode 100644
index 0000000000..47f80c29cd
--- /dev/null
+++ b/win32/README_FEATURES_MSVC.txt
@@ -0,0 +1,72 @@
+Preameble
+=========
+This file attempts to give further info about how to enable features
+that are not available in the Visual Studio project files shipped
+with the source release archive, i.e. beyond building GTK with the GDK 
+Win32 backend, with or without the Broadway GDK backend.
+
+The following also apply to Visual Studio builds done with Meson in terms
+of getting the required dependencies for the optional features.
+
+==========================================================================
+Notes on enabling EGL (ANGLE/D3D support) for Windows/Visual Studio builds
+==========================================================================
+There is now support in the GL context creation code for Windows in GDK for
+creating and using EGL (OpenGL ES 3) contexts, which can be used instead of
+the existing OpenGL (Desktop) support, especially when the graphics drivers
+do not support OpenGL adequately.
+
+This support is not enabled by default in the project files.  In order to do
+so, please do the following:
+
+-Obtain or compile a build of recent version of ANGLE.  The one that comes
+ with QT 5.10.x is sufficiently recent, but not the one that comes with QT-
+ 5.6.x.  Note that Visual Studio 2013 or later is required for building
+ ANGLE from QT-5.10.x, but the Visual Studio 2013-built ANGLE DLLs does 
+ work  without problems with GTK+ built with Visual Studio 2008~2013.  
+ You may need to obtain D3Dcompiler_[47|43|42].dll if it does not come 
+ with the system (which is part of the DirectX runtimes).  Visual Studio 
+ 2015 or later can use ANGLE from QT 5.11.x or later, or from Google's
+ GIT repos, which may require later version of Visual Studio to build.
+ Its headers and .lib needs to be set to be found by the compiler and 
+ linker   respectively before building libepoxy.
+-Build libepoxy with EGL support, which has to be enabled explicitly on
+ Windows builds.  Pass in -Degl=yes when building libepoxy using Meson.
+ Build and install, making sure the headers and .lib can be located by the
+ compiler and linker respectively.
+-Open the vsX/gtk+.sln, and open the project properties in the "gdk3-win32"
+ project.  Under "C/C++", add GDK_WIN32_ENABLE_EGL in the "Preprocessor
+ Definitions" to the existing definitions in there for the configuration
+ that is being built.  Then build the solution.
+-To force the use of the EGL code, set the envvar GDK_GL=(...,)gles , 
+ where (...,) are the other GDK_GL options desired.
+ 
+==============================================================
+Enabling the font tweaking features and the font features demo
+==============================================================
+The font tweaking features in the GTK DLL is enabled automatically if
+the Pango 1.44.0 and HarfBuzz 2.2.0 (or later) headers and libraries
+(and hence DLLs) are found during compile time.  Check in 
+gtkfontchooserwidget.c that the `#pragma comment(lib, "harfbuzz")` line
+to ensure that you have your HarfBuzz .lib file named as such, which
+is the default .lib name for HarfBuzz builds.
+
+Alternatively, they can be manually enabled by making sure that 
+`HAVE_HARFBUZZ` and `HAVE_PANGOFT2` are defined in config.h.win32,
+meaning that PangoFT2 must be present, which depends on HarfBuzz, 
+FontConfig and FreeType.  You will then need to add to the `gtk3`
+projects the .lib's of PangoFT2, HarfBuzz and FreeType in the 
+"Additional Libraries" entry under the linker settings.
+
+Please note that the font features demo is not built into gtk3-demo
+by default.  To do that, run in a Visual Studio command prompt, go to
+$(srcroot)\win32, and run
+"nmake /f generate-msvc.mak regenerate-demos-h-win32 FONT_FEATURES_DEMO=1".
+To undo that, run that command without "FONT_FEATURES_DEMO=1".  Python must
+be present in your PATH or passed in via PYTHON=<path_to_python_interpreter>.
+
+You will then need to add $(srcroot)\demos\gtk-demo\font_features.c into 
+the source list of the "gtk3-demo" project, and add the .lib file for 
+HarfBuzz, and if using pre-Pango 1.44.0 and/or pre-HarfBuzz 2.2.0, the 
+.lib files for PangoFT2 and FreeType into the "Additional Libraries" 
+entry under the linker settings.