DirectWrite is a glyph rendering API introduced by Microsoft, it was shipped with Windows since Windows 7. DirectWrite provides independent glyph rendering from the rendering system that enable Windows application developers to improve the text experience within their applications. In this case you can try to get high-quality rendering for many Asian and African scripts for screen rendering on Windows, especially for playing an slide show presentation via Impress. Since both Chrome and Firefox started using DirectWrite to render a glyph on screen on Windows, I think LibreOffice should do the same. On Firefox for Windows DW can be enabled or disable via a corresponding option in the about:config page.
We already use DirectWrite for OpenGL and Graphite support. Current GSOC Common SAL Layout w/Harfbuzz effort should improve things further and move us away from GDI and Uniscribe. =-ref-= http://opengrok.libreoffice.org/xref/core/vcl/win/gdi/winlayout.cxx http://opengrok.libreoffice.org/xref/core/vcl/win/gdi/winlayout.hxx https://cgit.freedesktop.org/libreoffice/core/log/?h=feature/commonsallayout
Oh, I forgot that I should add “provide an option to let user choose whether using DW to render text”
Well, I means we should allow users to use DirectWrite to render text without OpenGL.