On 5/17/2010 5:44 AM, Aekold Helbrass wrote:
Hi again!
Thanx for you fast and informative responses!
But now I am a bit confused. Roman tells that Freetype does the
rendering, but there is significant difference between Qt apps and
Java apps. See screenthos in attachments.
I think you misinterpreted. He's means that freetype produces the glyph
images.
There's no attachment. I think these mailing lists disallow them.
freetype has several knobs, and I don't know if Qt and JDK set them all
the same way.
I found native code that works with freetype and changed glyph loading
flags to the same as Qt has (i debugged it too), but they became even
unglier.
That doesn't add up.
Phil, why pisces isn't appropriate for B&W or LCD text? Just interesting...
its a grey-scale antialiasing rasteriser, not blitting code for already
prepared images
and grey-scale != B&W and grey-scale != LCD.
Point me please to right direction - to make Java font rendering
closer to Qt's should I learn pisces and compare it to Qt's rendering
or should I debug freetype invocations?
Probably look at the flags passed to freetype in each case. Revisit what
those glyph
loading flags are.
-phil.
Attachments:
snapshot11 - tiny java app with DejaVu Sans Mono, Plain, 12 size font.
snapshot12 - the same font of size 10 in KWrite.
I assume that size (and roundness) difference is because of 72 DPI in
Java and 96 in KDE, but difference in antialiasing is obvious.
On 5/16/10, Phil Race<[email protected]> wrote:
Expanding a little on Roman's comments :
freetype is a font scaler or rasteriser. eg It takes a TrueType font and
returns to
its requester a bitmap or greymap image, or a path describing the glyph
shape.
Its role does not extend to rendering (ie putting the results of
rasterisation
on a surface). This isn't an "openjdk thing". Its just that's the role
of freetype.
Yes it also obtains the metrics in most cases.
As Roman says there are specialised blitting routines for the text,
including
OpenGL pixel shader code, if that pipeline is optionally available and
enabled.
pisces isn't ever going to be the best (notably not the fastest) way to
get text
on screen and isn't appropriate for B&W or LCD text.
-phil.
Roman Kennke wrote:
Hello,
I want to hack into the sources of font rendering of openjdk, and I'm
a bit confused now. So help me please understand how it works. Links
are appreciated too.
I read that freetype is used for fonts scaling, but after debugging it
looks like freetype is used only to get font metrics, while real
rendering is done using Pisces. I know nothing about real font
rendering, so I have few questions about it:
1. am I right that freetype is used only to get font shapes while all
rendering and antialiasing is done using Pisces?
No, not really. The Java2D stack also gets the rendered glyphs from
Freetype as bitmaps. These are displayed by pisces similar to images.
2. isn't freetype can be used for font rendering and is used in GTK
and Qt? Or freetype is only scaler?
There's the interface FontScaler in the sources (search for it). If you
manage to implement this using GTK or Qt... AFAIK, GTK and Qt use
Freetype themselves, so there wouldn't be any significant improvement.
Plus, the FontScaler interface is quite low level, I guess you'd have a
hard time implementing this using GTK or Qt, which are somwhat
higher-level.
3. if freetype can be used for font rendering - why Pisces is used?
See above. Freetype does the actual rendering (anti-aliasing and such),
Pisces isn't really used, the resulting bitmaps are directly blitted to
the surface. Unless you're fetching the outlines and render them using
draw() or such, in this case freetype doesn't do the rendering. But
that's not the usual case.
4th and the most important - how are you guys debugging native code?
It's not supported with nbprojects, and I can't imagine how to launch
java with some application to debug some native code...
I prefer to use gdb. You can launch Java this way:
java -XX:OnError="gdb - %p" MyApplication
this jumps into gdb whenever something bad happens.
Kind regards, Roman
