- From: Charles Pritchard <chuck@jumis.com>
- Date: Tue, 10 Aug 2010 17:22:18 -0700
On Aug 10, 2010, at 4:09 PM, Ian Hickson <ian at hixie.ch> wrote: > On Thu, 8 Jul 2010, Charles Pritchard wrote: >> >> We've been doing some work with html line boxes; mainly, mixed font >> styles in a text area, using the HTML Canvas element. While Canvas >> fillText does have the textBaseline attribute, in order to set the >> current alignment, it does not provide enough metrics through the >> measureText function for us to exploit the textBaseline attribute across >> fonts (sizes and styles). >> >> Adding descent, to the measureText object would allow us to do more. >> Currently, TextMetrics only returns "width". I'm proposing adding >> "descent" to that list. > > I recommend not using <canvas> for text editing. I've worked on a substantial amount of code dealing with text editing. At present, the descent of the current font has been the only deficiency. I feel that using Canvas to implement HTML5/CSS provides a quality proof of the completeness of the 2D API. > > Adding more features to TextMetrics is on the cards for a future version > of the canvas API, but at the moment I'm waiting until more of the spec is > reliably implemented before adding more features, so that we don't get too > far ahead of the spec. We're fine simply including a table of descent metrics (they're essentially a single static value for each font). Exposing the metric value is a very simple process for implementors (low cost in time to implementation). I understand that the Canvas spec is essentially frozen (though this seems like a deficiency in the standard [why have textBaseline without it?]) -- I'd like to see some place to discuss the future standard, so as to avoid x-vend-descent as the property value. > > -- > Ian Hickson U+1047E )\._.,--....,'``. fL > http://ln.hixie.ch/ U+263A /, _.. \ _\ ;`._ ,. > Things that are impossible just take longer. `._.-(,_..'--(,_..'`-.;.'
Received on Tuesday, 10 August 2010 17:22:18 UTC