[whatwg] Enabling LCD Text and antialiasing in canvas

[Rik Cabanier]

On Wed, Apr 3, 2013 at 10:02 PM, Mark Callow <callow.mark at artspark.co.jp>wrote:

>  On 2013/04/04 13:50, Rik Cabanier wrote:
>
>
>
> On Wed, Apr 3, 2013 at 9:25 PM, Mark Callow <callow.mark at artspark.co.jp>wrote:
>
>> As screen pixel densities soar, it is increasingly the case that fonts
>> are stored simply as paths that are scaled, especially fonts which have
>> thousands of characters.
>>
>
>  No, that is not true.
> Talk to font vendors; fonts are not just a collection of path segments.
> They are also not rendered as paths; instead they should have specific
> renderers.
>
> The people who work on our HiGlyph library tell me it is changing. I have
> no references I can provide.
>

If there are new fonts that are simple shapes, you'd still have to deal
with all the old fonts that are not like that.


>
>
>
>>  Vertical and horizontal lines won't have any aliasing to begin with so
>> what are you talking about?
>>
>
>  Of course they have aliasing.  Why wouldn't they?
>
> Because they are vertical and horizontal, therefore no jaggies (aliasing).
>

Subpixel AA is a trick to increase resolution.
In this case, a line that is more than 1 device pixel would have grayscale
in all directions with regular AA, but only colors in x and y for subpixel
AA.


>
>
>>
>>  Text also has the nice property that it's filled with a solid color.
>>
>>  I know little about Canvas2D but I do know that PostScript and SVG both
>> support gradients etc. when filling text so your statement is wrong.
>>
>
>  I worked on the rendering engine of Illustrator and Acrobat for 11
> years. Subpixel AA is disabled for text that is filled with gradients or
> images and reverts to normal rendering. AFAIK there is no postscript
> implementation that supports subpixel positioning.
>
>  Can you point me to a spec where you can fill text in canvas with a
> gradient instead of a solid color?
>
> As I wrote, I don't know much about Canvas2D. Besides it wasn't clear that
> your comment referred only to Canvas2D.
>

This is a discussion on adding parameters to Canvas2D. Maybe that got lost
in the thread :-)