Hi David,
Thanks for the reference. It's quite a thorough consideration! The use cases they present are important ones. I had always assumed that the most useful thing about <canvas> was its potential for giving us pixel information from SVG images (currently unavailable within SVG), so it is disheartening to learn that this utility is almost non-existent (but for the server-side rasterization and round-tripping, or workarounds like http://code.google.com/p/canvg/). Accordingly, I hope that the authors' recommendation of a SVG.toDataURL() method is taken seriously by the SVG WG. The authors' conclusion that "The current security model is too tight for effective interaction with SVG. " is one I would completely agree with. Cheers David From: [email protected] [mailto:[email protected]] On Behalf Of David Leunen Sent: Friday, April 29, 2011 4:20 AM To: [email protected] Subject: Re: [svg-developers] SVG inside <canvas> David, I think the pixel manipulation failure is not a bug, but a security feature. See http://paksula.users.cs.helsinki.fi/svg_open_2010/demo.xhtml http://paksula.users.cs.helsinki.fi/svg_open_2010/demo-full.xhtml and http://www.svgopen.org/2010/papers/62-From_SVG_to_Canvas_and_Back/index.html for explanations. A canvas has an "origin-clean" flag that can be "dirty" which makes it "write-only". On Thu, Apr 28, 2011 at 9:50 PM, David Dailey <[email protected] <mailto:ddailey%40zoominternet.net> >wrote: > Compare the two files at > > http://srufaculty.sru.edu/david.dailey/svg/recent/htmlsvgcanvas7a.htm > > and > > http://srufaculty.sru.edu/david.dailey/svg/recent/htmlsvgcanvas7b.htm > > > > The first merely loads a jpg bitmap into a <canvas> and an SVG file into an > <embed> (I was using <img> instead, but some browsers seemed unhappy with > me > for that) > > > > When the button is pushed, a part of the canvas is read as a pixel array, > manipulated and then redisplayed. It works just fine in IE9, Opera, FF4, > Safari, Chrome. > > > > In the second file, two small differences: a)the file read into the canvas > is the same SVG as that in the embed, b) an alert is popped up to show the > src of the image object, once loaded into the browser, but prior to writing > into the canvas. > > > > No browser seems to pass this simple test. > > > > a) IE loads the SVG into the img, displays it in the canvas, but > refuses to manipulate the pixel array > > b) Safari loads the SVG into the img, displays it in the canvas (but > without antialiasing), and refuses to manipulate the pixel array > > c) Ditto for Chrome > > d) Firefox loads the SVG into the img, but doesn't display it or allow > pixel manipulation. > > e) Opera doesn't load the SVG into the img. > > > > I think I'd rather just add this to the acid test suite than to file five > separate bug reports. Heck, I'm too lazy for even that. Maybe I'll just add > it to my own private set of Cool tests (not having to do with Ken Kesey or > Ian Hickson). Of course, I suppose it is possible that the spec > specifically > allows browsers to give up at different points along this progression, > since > it is probably clear that I am up to no good! > > > > Cheers > > David > > > > [Non-text portions of this message have been removed] [Non-text portions of this message have been removed] ------------------------------------ ----- To unsubscribe send a message to: [email protected] -or- visit http://groups.yahoo.com/group/svg-developers and click "edit my membership" ----Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/svg-developers/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/svg-developers/join (Yahoo! ID required) <*> To change settings via email: [email protected] [email protected] <*> To unsubscribe from this group, send an email to: [email protected] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
