[OpenJDK 2D-Dev] <Swing Dev> RFR: 8189809: Large performance regression in Swing text layout.
philip.race at oracle.com
Mon Dec 11 22:39:54 UTC 2017
Yes, it should be negative since we want to use this as the y origin of
relative to the baseline. I am using it correctly in the height calculation.
40 float height = ascent + descent + leading;
541 return new Rectangle2D.Float(0f, ascent, width, height);
On 12/11/2017 02:12 PM, Sergey Bylokhov wrote:
> Hi, Phil.
> The new code will calculate the logical bounds this way:
> 541 new Rectangle2D.Float(0f, ascent, width, height);
> But previously it was:
> 2613 new Rectangle2D.Float(0, -tl.getAscent(), tl.getAdvance(),
> 2614 tl.getAscent() + tl.getDescent() +
> 2615 tl.getLeading());
> Note that the second parameter is negative, is it intentionally changed?
> On 07/12/2017 12:54, Phil Race wrote:
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8189809
>> webrev: http://cr.openjdk.java.net/~prr/8189809/
>> This partially addresses a slow-down in Swing.
>> Swing now usually calls Font.getStringBounds() instead of
>> FontMetrics().stringWidth for text measurement.
>> The latter has a fast-path for latin-only simple text.
>> The former does not .. and at a minimum uses GlyphVector.
>> This fix provides a similar fast path and for direct calls to these
>> methods (micro benchmarks)
>> that is latin text they are now very similar .. at least for typical
>> In this fix as well as making this change in the font code, I updated
>> Swing to more
>> be a little more efficient.
>> Before this fix I always saw Swing coming in with a char .. then
>> constructing a String from it.
>> Then it passes it to the font measurement code, which then decomposes
>> the string back into a char
>> If Swing directly uses the API that takes a char then we save some
>> It does not get back all of the loss by Swing since
>> 1) Swing has other overhead elsewhere - it seems
>> 2) Swing is making 90% of these calls for a single char.
>> This could be from where Swing naively tries to add up char advances
>> itself to
>> get a string advance.
>> We may have to come back to that later. Perhaps with new public
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the 2d-dev