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[whatwg] Still beating the drawString() dead horse...

From: Stefan Haustein <sh@kobjects.org>
Date: Tue, 14 Nov 2006 15:36:54 +0100
Message-ID: <4559D486.2040407@kobjects.org>
Arve Bersvendsen wrote:
> Let's see. CSS and an element interface provides:
>
> 1) Specified and predictable white-space handling
> 2) Specified and predictable font and font-size handling (fallbacks, 
> relative and absolute sizes)
> 3) Specified and predictable line-height handling
> 4) Inline formatting
> 5) Color handling
>
> A drawString would have to support all of these to be useful, and by 
> that time you'll have reinvented more of CSS than you'd want to.
It is not necessary to reinvent any CSS, CSS can be used for 2), so the 
predictability is the same. The remainder is out of scope for 
drawString() or handled by existing canvas mechanisms, and it is simply 
not true that drawString() is not usable without those features. I have 
provided several use cases for drawString() in earlier posts (labels in 
graph/map/data visualization), and I still do not see any use case that 
would justify the added weight and complexity of drawElement().

>   var myEle = document.createElement('p');
>   myEle.textContent("Hello \nWorld");
>   // Or choose any other method of attaching style attributes to 
> elements.
>   myEle.style = "color: blue; white-space: pre; font-size: 12px; 
> line-height: 2; width: 100px; height: 100px;"
>   // ...
>   myCanvas2dContext.drawImage(myEle.drawElement(),0,0)
>
> Not too complicated.
The implied overhead makes me feel extremely uncomfortable with this 
approach.

Also, what happens if the text does not fit in 100x100 px? How do I 
figure out how much space the text actually occupies without starting to 
look at Image pixel values -- I may e.g. want to reduce the map detail 
level when the user increases the text size...

If you have drawElement() already implemented in Opera, and 
drawElement() is sufficient powerful, it should be easy enough to 
provide a simple drawString() for those who like to keep simple things 
simple...

Best regards,
Stefan





 
Received on Tuesday, 14 November 2006 06:36:54 UTC

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