OpenGL backend does not support images

[MCOfficer]

As per #354:

The OpenGL renderer still does not support the Image and Svg widgets, but I believe we can tackle that in another PR.

Also in that PR's discussion:

Are there any estimates on how hard it is to implement image support for OpenGL renderer ?

hecrj on 8 Jul 2020:

It shouldn't be hard to get a similar implementation to the iced_wgpu one.
However, we should try to abstract and move the atlas logic to iced_graphics instead of duplicating code. Additionally, it would be great to set the foundations for asynchronous loading of images at the same time. This is the hard part.

It's not ideal that I'm creating this tracking issue, but imo it's better than not having a tracking issue at all.

[JoshStrobl]

Just chiming in here. I wanted to evaluate iced as an alternative to GTK4 when porting over my GTK4+C Linux audio manager to Rust. This backend makes heavy use of iconography for "normal" UX elements, for example various buttons for playback. The lack of support for images on the OpenGL backend is of considerable impact, as unfortunately I can't rely on the end user having hardware supported by wgpu. I fully understand that iced is experimental and not remotely comparable to something like GTK4 at this time, however my hope is that this will be treated with some priority for resolution before the grand 1.0 release.

[MCOfficer]

Just in case this helps you or anyone else: If you don't load images dynamically, i.e. they are known to you at compile/development time, you might be able to work around it using vector graphics. Specifically, one of my projects uses font characters for iconography, which works perfectly and is more painless once you want to change their scale. You can also use the Svg widget for the same purpose.

Edit: See the svg example for Svgs, and todos for font icons.

Edit 2: removed the references to Svg, read on for the reason.

[JoshStrobl]

@MCOfficer So Svg works? Per your OP it mentions:

The OpenGL renderer still does not support the[...] Svg widgets

Has this changed since April 26th?

[MCOfficer]

@MCOfficer So Svg works? Per your OP it mentions:

The OpenGL renderer still does not support the[...] Svg widgets

Has this changed since April 26th?

Ah damn, i might have told a lie there.

I just quickly grepped the source and found this line in the glow backend, which I assumed was Svg support:

https://github.com/hecrj/iced/blob/a2b1ba522a8b90a2e539fff5936c798efc3f3807/glow/src/backend.rs#L224

But as it turns out, that line was last changed by the PR my OP refers to, so if hecrj says in this PR that Svg isn't supported, I gotta trust that. Sorry for causing confusion.

[hecrj]

Closing this in favor of #674.