[OpenJDK 2D-Dev] RFR: 8132890 Text overlapping on dot matrix printers.

[Phil Race]

On 10/20/2015 12:32 PM, Jennifer Godinez wrote:
> Hi Phil,
>
> I assume you've run all the manual regression tests on text?

I would not say all. But I have run the ones that relate
to text size/position/transform.

> The copyright year in the regression test needs updating.

We don't need to do that as there will be a script run to
update all files touched in 2015.

-phil.

> Otherwise, looks good.
>
> Jennifer
>
> On 10/16/2015 04:16 PM, Phil Race wrote:
>> https://bugs.openjdk.java.net/browse/JDK-8132890
>> http://cr.openjdk.java.net/~prr/8132890/
>>
>> The notable thing about this case is that the printer has different 
>> dpi in x and y.
>>
>> In GDI printing we detect when the transform under which the font is
>> rendered is non-uniform as in that case we want to tell GDI to create
>> a stretched font as that is better than trying to draw the text as a 
>> filled path.
>> What happens here is that the *device resolution* is not uniform.
>>
>> It is a scale of (3.33, 2.0) - ie 240x144 dpi so x=1.66*y
>>
>> This device resolution then gets combined with any graphics transform
>> and the font transform and we have lost sight of the fact that the
>> non-uniform part came from the device rather than the application
>> specifying an additional x-scale factor to be applied.
>> GDI is already accounting for the real device resolution and we cause
>> it to be applied twice.
>>
>> So we need to divide this out as part of the calculation.
>> This needs access to the real device dpi to be passed in/made available.
>>
>> But there is another issue.  JDK puts the printer job into portrait mode
>> even in landscape printing and takes care of the transforms itself.
>> So the size used to set the font for GDI needs to use GDI's idea of 
>> the orientation.
>>
>> I augmented a text printing test used to verify this with some 
>> additional scenarios.
>> It is now a pretty comprehensive test of many different scenarios.
>> It has been tested on an HP LaserJet, the Oki dot matrix printer and 
>> the XPS driver.
>>
>> There is also a not completely necessary tweak here to adjust the 
>> error we
>> allow in gdi vs jdk advances from 0.2% to 1%. This made for about a 25%
>> reduction in the overall spool file size for my test with no 
>> noticeable consequences.
>>
>> -phil.
>>
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.openjdk.java.net/pipermail/2d-dev/attachments/20151020/71bb795d/attachment.html>