[whatwg] Text APIs on <canvas>
Mathieu HENRI
p01 at opera.com
Tue May 6 10:48:21 PDT 2008
Ian Hickson wrote:
> I have introduced the following APIs:
>
> context.font
> context.textAlign
> context.textBaseline
> context.fillText()
> context.strokeText()
> context.measureText()
>
> They are defined here:
>
> http://www.whatwg.org/specs/web-apps/current-work/#text
>
> I haven't provided a way to render text to or along a path, nor a way to
> do vertical text, nor a way to measure anything but the nominal layout
> width of text (e.g. there's no way to measure bounding boxes or get
> baseline metrics). I also haven't provided a way to render document
> fragments straight to a canvas.
>
>
> Here is some of the feedback on canvas related to text. I have snipped the
> feedback that wasn't constructive or didn't provide anything beyond
> requests for features without use cases and rationale, or that just
> bickered back and forth without making progress. If I snipped something
> that you think I should have responded to, please let me know. (I did take
> everything into account, even the bits that I haven't included below.)
>
> I haven't made many comments below, because I didn't really have much to
> say. There were a lot of proposals and requests, but at the end of the day
> there didn't seem to be strong arguments in favour of some things or other
> things, so I haven't tried to defend the proposed API I put in the spec
> relative to the other APIs that were proposed. (I did take the various
> proposals that were made into account, and tried to adopt the best parts
> of each one.)
>
> If you have further feedback, please send comments to the list, as usual.
I can't see any mention that support for Text is optional. Is it
reasonable with browsers approaching major releases ?
The TextMetrics MUST return have 2 Float readonly properties : the width
and height. The width alone is not enough.
The methods fillText() and strokeText() could have a 5th optional
boolean argument called wrapText ( false by default ) to specify if the
text should wrap or the font-size be decrease in case the text is wider
than maxWidth.
It is unclear whether the transformations affect the text.
--
Mathieu 'p01' HENRI
JavaScript developer, Opera Software ASA
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