Authors are not going to think about
they want to use a complex image. If they want to use an image they
will simply use
It is illogical to require
img to be encased in
canvas in order to provide a long description.
Semantic elements and attributes improve communication. For details please consult the semantics document.
The semantics of
canvas element does not provide a clear, direct,
explicit, and strong semantic for an image long description.
canvas to supply long descriptions would
introduce needless complexity.
This in turn would make it more prone to authoring error as complexity confuses and leads to
longdesc is a simple link - no coordinates
to figure out.
canvas overloads fallback content.
No examples in the wild of accessible long text alternatives
canvas have been presented for any of the use
cases. No evidence exists that authors have or will use this
No tutorials, books, or documentation exists that explain to
authors how to make an accessible long text alternative with
No evidence has been presented that
more accessible content for long descriptions than
longdesc or that more authors would use it
canvas technique for long descriptions lacks backwards compatibility. It is
For further rationale please consult the backwards compatibility document.
Any proposed solution should be easy for authors who are already
publishing content with
longdesc to retrofit their
canvas possesses a radically
different, authoring pattern than
longdesc. Because of
this, retrofitting with
canvas would be difficult,
labor intensive, and error prone.
No retrofitting is required for
longdesc as it is an existing HTML feature not a new one.