Re: [ft] Render differences on embedded ARM vs other platforms

[Werner LEMBERG]

> Recently, we moved from an RGBT 5551 internal color configuration to
> an RGBA 8888 configuration.  There is a shared “core” application
> with a platform specific hardware abstraction layer.  The code is
> compiled for windows, mac, linux, android, ios, and an embedded ARM
> hardware system (mix of 32 and 64 bit versions).

This mix might be the culprit.

>   2.  Could this be some sort of a floating point rounding behavior
>   issue? (hw float on the ARM rounding differently than hw/sw on the
>   other systems for example)

No, since FreeType doesn't use floating point numbers.

> Basically, I am hoping for a start on where to even begin trying to
> track this down.  The goal would be for rendering to be identical
> across all platforms.

I suggest that you start with the current git version of FreeType and
create a small C code file that renders exactly one of the problematic
glyphs into a buffer, using the same load flags as in your real
application.  You should compile the code with debugging activated,
then set the environment variable

  FT2_DEBUG=any:7

and redirect your program's stderr output to a file.  If you compare
the output compiled on different platforms you get some first hints
where the (important) differences are.


    Werner