[ft-devel] Possible implementation error of function FT_Bitmap_Embolden()

[Chi Nguyen]

To freetype maintainers,

In developing the test for the freetype function FT_Bitmap_Embolden(), we
have encountered the following possible implementation error.

The specification for FT_Bitmap_Embolden() stated that:

"Embolden a bitmap. The new bitmap will be about `xStrength' pixels wider
and `yStrength' pixels higher. The left and bottom borders are kept
unchanged."

However, after we called this function to embolden a character, the bottom
border is not kept unchanged. As a result the top border is unchanged.

There is an inconsistency between the spec and the implementation. 
 
We have tested this on 32-bit and 64-bit x86 based test systems running
under the following distros OpenSuSE 11 (32 bit), Ubuntu 8.04 (ia32), RHEL52
x86-64, SLES 10.1 (32bit), Fedora 9 (32bit) with freetype 2.1.10 and
freetype 2.3.7.

Included with this email is a c program bitmap_embolden.c to help
demonstrate the bug described.

To reproduce the bug, use:
./bitmap_embolden <fully path-ed font_file_name> <char> <X-strength>
<Y-strength>

For example: 

./bitmap_embolden FreeMono.ttf M 512 512

Or 

./bitmap_embolden ./fonts/FreeMono.ttf M 512 512

if the specified <font_file_name> is located in the local directory ./fonts.

Thank you very much for your time and please let us know any ruling/finding
that you may have.


Sincerely yours,


Nguyen Trung Chi

NEC Solutions VietNam

bitmap_embolden.c
Description: Text document