On Wed, Jul 28, 2010 at 11:39 PM, David Flanagan <da...@davidflanagan.com> wrote: > James Robinson wrote: >> For example, I think >> drawing a 20x20 image into a 500x500 canvas without scaling with a >> globalCompositeOperation of 'copy' should result in only the 20x20 region >> being cleared out, not the entire canvas. > > Yikes! It hadn't occurred to me that copy should behave that way. But > you're right that that is what the spec requires. Opera does it that way. > Firefox, thankfully, does not. > > Perhaps independently of the debate over infinite bitmap vs. shape extents, > we can agree that "copy" is a special value that means "do not perform > compositing"
That value already exists - it's called "source-over". "copy" does some special compositing stuff no matter whether you do "global" or "local" compositing - try using 'copy' when the source has .1 opacity. ~TJ
