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Dave, various
implementations use different libraries/approaches for the
Graphics.
Way of tuning parameters and their set can be
different. I think that it is simply not possible
to generalize them all. At least something generic like preference=quality/speed switch makes
real sense.
Technically it is better to allow to get two
Graphics instances for the same canvas and use
them at the same time if really needed. In any
case 2D and 3D graphics shall coexist on the same
surface.
So why not 2D and 2D-fast ?
In any case it is up to UA to provide multiple
implementation for different values of contextID.
contextID as a string is there in purpose I belive.
That is the one.
Andrew Fedoniouk.
----- Original Message -----
Sent: Friday, October 20, 2006 10:12
PM
Subject: Re: [whatwg] Canvas draw
quality
I
don't think a totally different context is a good idea. Sometimes you
want to mix antialiased and non-antialiased modes.
The API in CG is part of the graphics state...
CGContextSetShouldAntialias
I don't think an API like this should be vague about what it's doing...
e.g., just using vague terms like "quality." We should say what we
mean... antialiasing for example.
dave
On Oct 20, 2006, at 10:01 PM, Andrew Fedoniouk wrote:
----- Original Message
-----
Sent:
Friday, October 20, 2006 9:09 PM
Subject:
[whatwg] Canvas draw quality
I would like to see a property added to the 2d canvas context that
would allow quality to be lowered for drawing functions. Normally any time
a shape is drawn, pixels close to the boundary are made semi transparent
to make it look smooth, this is usually favourable but I have had a need
to draw shapes and lines with pixel sharp boundaries in the same way as
Java normally does. I would imagine that with the setting enabled, only
the integer part of linewidth would be used. This setting would also
affect drawing images, making them have no blurring or approximating when
scaled or rotated.
This could easily be
implemented without affecting old scripts, making a property such as
lowQuality = true; (default false). Or perhaps allowing more control: a
float from 0 (low quality) to 1 (high quality), and interperating null as
1 for backwards compatibility.
This property could also
be handy in instaces where both fill() and stroke() are being called. Low
quality could be used on the fill() to improve performace while stroke()
could be used with high quality so it still draws smoothly.
I think that the best way is
just to define different values for the context ID: DOMObject getContext(in DOMString contextID);
Something like "2D" and
"2D-fast" or "2D-simple".
Another option would be to add
one optional parameter to the getContext() function.
I doubt that someone will need
to switch it in the middle of drawing so
having such switch as
an attribute is redundant.
Andrew
Fedoniouk.
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