[Webkit-unassigned] [Bug 16045] New: Safari 3 <canvas> regression with transparent radial gradient rendering

[bugzilla-daemon at webkit.org]

http://bugs.webkit.org/show_bug.cgi?id=16045

           Summary: Safari 3 <canvas> regression with transparent radial
                    gradient rendering
           Product: WebKit
           Version: 523.x (Safari 3)
          Platform: Macintosh
               URL: http://darknoon.com/organics/render.html
        OS/Version: Mac OS X 10.5
            Status: UNCONFIRMED
          Severity: Major
          Priority: P2
         Component: Layout and Rendering
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: andpoul at gmail.com


A radial gradient rendering bug in <canvas>, where under certain conditions, we
see improper display. This did not happen in ~late summer builds of webkit.

Steps to reproduce:
1) Load http://darknoon.com/organics/render.html
2) Notice the square border visible around the inner circular area. This is a
bug.

In the example page, this is the relevant code:

function makeMaskGradient() {
        gradient = ctx.createRadialGradient(300, 300, 250/*inner rad*/, 300,
300, 300/*outer rad*/);
        gradient.addColorStop(0.00, "rgba(" + pageBackground + ", 0.0)");
        gradient.addColorStop(0.8, "rgba(" + pageBackground + ", 0.1)");
        gradient.addColorStop(0.97, "rgba(" + pageBackground + ", 0.3)");
        gradient.addColorStop(1.0, "rgba(" + pageBackground + ", 1.0)");
        return gradient;
}

webkit now seems to freak out about the transition from colors at 0.97 and 1.0,
jumping up in opacity from 0.3 to 1.0;

I'll try to work on a reduction, but the issue should be clear here. The actual
rendering is that even after the 1.0 level is met, outside values (after the
gradient transition) do not have the appearance of 1.0; they stay partially
transparent, which is not good for the rendering of my program. I'm looking at
a workaround, but none is immediately clear besides using an image instead of a
gradient.


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