[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [ft] CFF outline rendering problem

From: Róbert Márki
Subject: Re: [ft] CFF outline rendering problem
Date: Tue, 7 Dec 2010 08:45:11 +0100


You're right, the example should be corrected.
Thanks again for fixing this bug!

I've noticed you changed the filename of the example to example4.cpp, you should modify the include directive at the end of the file too to be able to build it. The generated file will be called example4.moc in this case.
So this line:
#include "main.moc"
  should be changed to
#include "example4.moc"

On Tue, Dec 7, 2010 at 8:08 AM, Werner LEMBERG <address@hidden> wrote:

In October I wrote:

>> I have tested it and it works.  All the glyphs rendered with
>> FT_RASTER_FLAG_DIRECT flag look the same as if they were rendered
>> onto a bitmap.
> Unfortunately, this isn't true.  Compiling the attached example4.cpp
> and comparing
>   ./example4 /windows/C/WINDOWS/Fonts/pala.ttf y 200 0
> (image `not-direct.png') with
>   ./example4 /windows/C/WINDOWS/Fonts/pala.ttf y 200 1
> (image `direct.png') you can easily see rendering differences.  In
> particular, the direct rendering is not correct, producing too wide
> images.

Fortunately, this my suspicion:

> Reason for the mismatch are negative x and y coordinate values in
> the data fed to the smooth renderer, I believe, causing rounding
> errors.  In non-direct `mode', the outline is first shifted to have
> no negative coordinates so the problem is not seen.

was incorrect.  Comparing the debugging output (using FT2_DEBUG=any:7)
shows that only the colours differ minimally but not the coordinates.

The real problem is that a Qt line consists of at least two pixels!

 painter->drawLine(0, 0, 0, 0);

draws nothing.  Consequently, this code in example4.cpp

 if (span.len > 0)
   painter->drawLine(span.x, y, span.x + span.len, y);

must be replaced with

 if (span.len > 1)
   painter->drawLine(span.x, y, span.x + span.len - 1, y);
   painter->drawPoint(span.x, y);

and the shapes become identical.  Finally, I've added


so that the direct rendering becomes really black also.

I've now added the files to


reply via email to

[Prev in Thread] Current Thread [Next in Thread]