<Swing Dev> [9] Review request for 8132119 Provide public API for text related methods in SwingUtilities2

[Phil Race]

Glyphs are always rasterised in device space so it does mean device space.
The identity transform therefore happens to always return a user space
advance is that is an integer, but it is not bound to be so under any 
other transform.

-phil.

On 04/26/2016 03:28 PM, Sergey Bylokhov wrote:
> On 27.04.16 0:34, Phil Race wrote:
>> Fractional metrics being "off" does not mean that *user space* advances
>> need to be integers,
>> it refers to *device* space advances. Of course if your API does not
>> support floats you have a
>> problem - particularly if - you are character advance adding in which
>> case it is better to ask the
>> font system for the overall advance of the text.
>> https://docs.oracle.com/javase/8/docs/api/java/awt/RenderingHints.html#KEY_FRACTIONALMETRICS 
>>
>
> The documentation says that in case of "fm-off" the "simplified system 
> based on integer device positions is typically used" + "rounding 
> advance widths for rasterized glyphs to integer distances", it does 
> not say that the "integer distance" should be rounded to the nearest 
> device/pixel. It says that "rounding operations as the high quality 
> and very precise definition of the shape and metrics of the character 
> glyphs must be matched to discrete device pixels" I guess we should 
> confirm the specification because results of the fix will be "discrete 
> number of device pixels", isn't it?
>