[whatwg] Canvas roundedRect

[David Dailey]

It seems to me that the primary use of rounded rectangles is for UI's rather
than art, and as such, SVG, that supports DOM and events, already has syntax
for rounded rectangles. I have seen how the <canvas> folks like to re-invent
wheels, but the path syntax within canvas already should allow creation of
line arc line arc sequences, and making things too easy would not appeal to
the <canvas> machismo would it?

How many rounded rectangles have you ever seen that don't invite
mouseclicks? And then do you really want to try to calculate whether or not
the mouse event is atop one of those thingies, particularly after it has
been rotated, scaled and skewed? 

I'm just not seeing why <canvas> would need this.

Regards
David

-----Original Message-----
From: whatwg-bounces at lists.whatwg.org
[mailto:whatwg-bounces at lists.whatwg.org] On Behalf Of Igor Trindade Oliveira
Sent: Thursday, June 21, 2012 12:59 PM
To: whatwg at lists.whatwg.org
Subject: [whatwg] Canvas roundedRect

Currently, canvas2d does not have support for rounded rectangles and the web
developers are implementing rounded rectangles using arcs or bezier
curves.[1][2] So i propose the addition of two new functions:

void fillRoundedRect(unrestricted double x, unrestricted double y,
unrestricted double w, unrestricted double h, unrestricted double xRadius,
unrestricted double yRadius); void strokeRoundedRect(unrestricted double x,
unrestricted double y, unrestricted double w, unrestricted double h,
unrestricted double xRadius, unrestricted double yRadius);

Where the xRadius and yRadius arguments specify the radii of the ellipses
defining the corners of the rounded rectangle.

Additionally, if we know that the path is a rounded rectangle, we can make
optimizations in the graphics libraries reducing the amount of tesselations.

[1] http://www.scriptol.com/html5/canvas/rounded-rectangle.php
[2]
http://www.supercalifrigginawesome.com/Extending-Canvas-to-Draw-Rounded-Rect
angles