- From: Ben Boyle <benjamins.boyle@gmail.com>
- Date: Mon, 6 Aug 2007 20:38:37 +1000
- To: "Philip Taylor" <philip@zaynar.demon.co.uk>
- Cc: "HTML WG" <public-html@w3.org>
Thanks for the clarification - much appreciated! Worth adding to the spec as a note I think. On 8/6/07, Philip Taylor <philip@zaynar.demon.co.uk> wrote: > Ben Boyle wrote: > > [quoting from the spec] The canvas must initially be fully transparent black. > > I think that sentence should be modified to say "The canvas bitmap must > initially be fully transparent black.", so it's clear that it applies to > the bitmap rather than to the element itself. > > > 1. "transparent black" ? Transparent I understand. Why black? > > "Transparent black" means rgba(0, 0, 0, 0). A colour like rgba(255, 0, > 255, 0) would be fully transparent too (but not black). Normally all > fully transparent colours act indistinguishably, but you can call > CanvasRenderingContext2D's getImageData() to see the difference between > [0, 0, 0, 0] and [255, 0, 255, 0], so the distinction matters a bit > here, and specifying "transparent black" ensures everyone implements the > same. > > > This would be adjustable through CSS? > > You can't change the canvas bitmap with CSS. If you do <canvas > style="background:red"> then the canvas is still initially a transparent > black bitmap, though it's rendered on top of a red square (which is > rendered on top of whatever's behind the canvas element). (I don't know > whether the rendering is actually specified anywhere, but it's > consistent with how <img> works.) > > -- > Philip Taylor > philip@zaynar.demon.co.uk >
Received on Monday, 6 August 2007 10:49:58 UTC