[Interest] Native text rendering in Qt 5.1 on Windows

John C. Turnbull ozemale at ozemail.com.au
Wed Aug 21 11:40:21 CEST 2013

Thanks Andrew,

As I don't have immediate access to the codebase, are you able to tell how
those glyph paths generated by GDI get rendered in an OpenGL context?

-----Original Message-----
From: Knight Andrew [mailto:Andrew.Knight at digia.com] 
Sent: Wednesday, 21 August 2013 19:27
To: John C. Turnbull; 'Joseph Crowell'; interest at qt-project.org
Subject: RE: [Interest] Native text rendering in Qt 5.1 on Windows

Unless the non-default configure option -directwrite is passed to qtbase at
configure time, the Windows QPA plugin generates glyph paths using GDI. See
qtbase/src/plugins/platforms/windows/qwindowsfontengine.cpp. If configured
with DirectWrite, the experimental DirectWrite font engine is used.

Note that there is a comment saying that the Windows font engine "Will
probably be superseded by a common Free Type font engine in Qt 5.X.", but
I'm not aware of the status of that.


From: interest-bounces+andrew.knight=digia.com at qt-project.org
[interest-bounces+andrew.knight=digia.com at qt-project.org] on behalf of John
C. Turnbull [ozemale at ozemail.com.au]
Sent: Wednesday, August 21, 2013 12:02 PM
To: 'Joseph Crowell'; interest at qt-project.org
Subject: Re: [Interest] Native text rendering in Qt 5.1 on Windows

Thanks Joseph but that link doesn't answer my question as to how the native
text is actually rendered i.e. what library/technology.

I would like to know because my (limited) understanding of Qt is that it
uses OpenGL for graphics (even on Windows) and, given that OpenGL does not
have any native font rendering API, how is the text rendered in a "native"
way so that it appears in an OpenGL context?  For example, is DirectWrite
used to render the text to a buffer which is then blasted into the OpenGL

From: interest-bounces+ozemale=ozemail.com.au at qt-project.org
[mailto:interest-bounces+ozemale=ozemail.com.au at qt-project.org] On Behalf Of
Joseph Crowell
Sent: Wednesday, 21 August 2013 18:32
To: interest at qt-project.org
Subject: Re: [Interest] Native text rendering in Qt 5.1 on Windows

Here's an blog about that feature from digia.

On 21/08/2013 08:33 AM,
ozemale at ozemail.com.au<mailto:ozemale at ozemail.com.au> wrote:
With Qt 5.1 I am able to choose "native" text rendering for my QML text

What does "native" actually mean here on Windows?
What is actually used to render such text on Windows? (i.e. is it
DirectWrite or some other method)




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