W3C home > Mailing lists > Public > www-style@w3.org > February 2010

Re: Feedback on 'image-fit' and 'image-position'

From: fantasai <fantasai.lists@inkedblade.net>
Date: Thu, 18 Feb 2010 00:44:22 -0800
Message-ID: <4B7CFDE6.2000800@inkedblade.net>
To: Simon Pieters <simonp@opera.com>
CC: www-style@w3.org
On 02/18/2010 12:00 AM, Simon Pieters wrote:
> On Thu, 18 Feb 2010 00:01:06 +0100, fantasai
> <fantasai.lists@inkedblade.net> wrote:
>> My current mental model for the rendering of replaced content is the
>> following:
>> 1. CSS queries the object for its intrinsic size.
>> 2. CSS computes the size of the CSS content box based on this info
>> and the CSS properties applied to the replaced element.
>> 3. CSS adjusts the viewport for the replaced element:
>> - to match the size of the content box for image-fit: fill
>> - to cover the size of the content box while preserving the
>> intrinsic aspect ratio for image-fit: cover
>> - to contain the size of the content box while preserving
>> the intrinsic aspect ratio for image-fit: contain
>> 4. CSS adjusts the position of the viewport with respect to the
>> content box according to the specified image-position.
>> 5. CSS gives the object its viewport dimensions and asks it to render.
>> 6. The object renders into its given viewport according to its own
>> rendering rules. (For SVG, this could include accounting for
>> preserveAspectRatio. For videos, it could mean using 'content')
>> 7. CSS clips any parts of the viewport that extend beyond the
>> content box.
>> In the above mode, the only interaction between CSS and the replaced
>> content is:
>> a. The replaced content reports its intrinsic size
>> b. CSS tells the replaced content the size of its viewport
>> I think it's important for there to be no format-specific negotiation
>> between the replaced content and CSS. The model should be defined so
>> that SVG doesn't need any special exceptions. The rules in CSS should
>> be able to handle <iframe> content, plugins, videos, bitmap images,
>> SVG, <canvas> and any other replaced content the same way.
> Browsers have format-specific rules today. <object> can use different
> formats. Therefore, for compat, <object> needs format-specific rules.
> Hence the new 'auto' value.

But does *CSS* need format-specific rules, or can those be handled in
step 6? It seems to me they can be handled in step 6.

Received on Thursday, 18 February 2010 08:54:40 UTC

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