Comment #5 on issue 191 by [email protected]: Disabling FRACTIONAL_METRICS
on Windows yields incorrect bounds for text PSwing components
http://code.google.com/p/piccolo2d/issues/detail?id=191
Here's a summary of this issue to date:
While the default for all platforms seems to be FRACTIONAL_METRICS_ON
("fm_on"), Piccolo2D explicitly sets FRACTIONAL_METRICS_OFF ("fm_off") for
painting of PSwing nodes. As I understand it, this decision has been a part
of the PSwing class for a long while now and the primary motivation for
doing this is to avoid rendering of ellipses on Mac OS X platforms (by
using "fm_off", we prevent Mac OS from rendering ellipses for some text
renderings that, due to fractional metrics calculations can't fully render
within their bounds.)
After running several tests, however, it seems that painting w/ "fm_off"
causes more unpleasant behavior across systems than using the default
of "fm_on". On all systems, using "fm_off" causes noticeable jittering
while zooming. On Ubuntu/Java4, ellipses are actually rendered in this mode
and not in "fm_on". And on Windows 7, using Java4, ellipses are rendered
regardless of the setting.
I tested on a subset of {Win7, Snow Leopard, Ubuntu10} x {Java4, Java6} x
{FRACTIONAL_METRICS_ON, FRACTIONALMETRICS_OFF} and the outcome images will
come soon attached with tell-tale filenames:
| "fm_off" | "fm_on"
Windows7
Java4: jittering; ellipsed no
jitter; ellipsed
Java6:
jittering slight jittering
Ubuntu10
Java4: jittering; ellipsed
slight jittering
Java6 (openjdk): jittering; slight artifacts no jitter;
noticeable artifacts
Mac/Snow
Java6:
jittering slight jittering; ellipsed
It appears impossible to avoid ellipse-rendering using RenderingHints.
Also, using the default rendering hint "fm_on" yields much better behavior
(little or no jittering) otherwise.
It seems clients can avoid ellipses by explicitly setting preferred sizes
on their components, so there is a workaround.
With this data, I believe the *correct* route is to use the default "fm_on"
rendering hints (which is default on all systems I tested on), which also
resolves this issue.
I don't believe we can do this, however, in 1.3.* releases as clients may
already rely on this behavior. 1.3.* clients can workaround this issue by
overriding paint() behavior (not ideal, I know.)
Looking for P2D developers to comment. My vote is to move this ticket to
2.0 with the plan of removing our use "fm_off" in 2.0.
--
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