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

[Jennifer Godinez]

Hi Phil,

I assume you've run all the manual regression tests on text?  The 
copyright year in the regression test needs updating.  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.
>

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