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Re: [csswg-drafts] [css-images-4] image() function for solid colors needs more thought

From: Tab Atkins Jr. via GitHub <sysbot+gh@w3.org>
Date: Thu, 07 Dec 2017 19:36:43 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-350071748-1512675402-sysbot+gh@w3.org>
> You'll have to specify the width and height too;

No, it's just a dimensionless image, same as an SVG with no width/height/viewBox attributes.  It thus stretches to fill the painting area.

> In addition, if this functionality exists then it should be a "first class" image type, not just there as a fallback when a image fails to load from a URL. 

That definitely already works. `image(blue)` is totally valid per the syntax, and does what you expect it to do.

> Finally, while a generated solid-color image is a nice idea for anyone creating test-cases, the apparent goal (preventing background-color leak-through under a translucent background image while still setting a background if the image is missing) is pretty specific and could probably be achieved in an easier way.

That's the primary goal, yes, but there are other use-cases for being able to declaratively generate solid-color images, such as for filter inputs; SVG has the `<solidColor>` filter element specifically for this reason.

> could perhaps be achieved with a "final" (or maybe "stop") ident after the last image in the background stack, to prevent the processing of any further layers in the background if it's successfully loaded.

The primary use-case applies to many more properties than just 'background-image'. We'd have to figure out some way to apply this approach to all of them, including places that take a single `<image>` rather than a list. `image()`, on the other hand, automatically works everywhere that takes an image, and the fallback behavior is a natural extension of the existing "provide multiple URLs" fallback behavior.

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Received on Thursday, 7 December 2017 19:37:00 UTC

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