Hello,
We have a strange rendering issue with freetype library that is driving
us to ask an opinion from you.
Our application is using two free true type fonts: DejaVuSans.ttf and
DejaVuSans-Bold.ttf, in monochrome bitmap way, with horizontal
alignment; the issue basically consists in the following: the 'r'
character is being displayed in a higher position, on the baseline.
Two different versions of freetype library are producing a different
result:
- a relative recent version of ft (2.4.6) is showing the problem
- an older version of ft (2.3.9) is properly displaying the character
I have made some debug and discovered the following:
- If I reduce the horizontal bearing Y parameter, the char is properly
aligned on the baseline
- the metrics are showing me that there is not difference on the values
that are managing the bitmap glyph, so it seems that the horizontal
bearing Y recovered from the font file, through the library are the
same. So, since the code base that is managing the application is the
same, I am wondering where the issue is.
I have created a prototype application that loads the font, render them
in a txt file with a specific char in the pixels that are full of color
('o') and also prints out the metrics values. The code is in attachment.
The final result is that old version of freetype load the glyph in this
way
....
OOO.
O...
O...
O...
O...
O...
bitmapGlyph->metrics:
bitmapGlyph->metrics.height 7
bitmapGlyph->metrics.horiAdvance 4
bitmapGlyph->metrics.horiBearingX 1
bitmapGlyph->metrics.horiBearingY 7
bitmapGlyph->metrics.vertAdvance 11
bitmapGlyph->metrics.vertBearingX -2
bitmapGlyph->metrics.vertBearingY 3
bitmapGlyph->metrics.width 4
while the new one:
OOO
O..
O..
O..
O..
O..
bitmapGlyph->metrics:
bitmapGlyph->metrics.height 7
bitmapGlyph->metrics.horiAdvance 4
bitmapGlyph->metrics.horiBearingX 1
bitmapGlyph->metrics.horiBearingY 7
bitmapGlyph->metrics.vertAdvance 11
bitmapGlyph->metrics.vertBearingX -2
bitmapGlyph->metrics.vertBearingY 3
bitmapGlyph->metrics.width 4
So I can see a difference on the bitmap, but since the font file is the
same, the code is the same, just the freetype libraries are different.
I am wondering if there is another parameter or test that I can do in
order to understand what is going on; have you got any suggestions?
Thanks in advance for your consideration.
Mauro
<<image001.gif>>
test.cpp
Description: test.cpp
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