New marker symbol type for "Animated Marker"

[nyalldawson]

This new marker symbol type allows points to be rendered using an animated marker, sourced from an animated gif, webp or mng animation.

Options are present for marker file, size, angle and frame rate.

There are two ways in which animated symbols are handled:

1. If the map itself is considered an animation, then the frame rendered for the animated marker is based on the map animation
   frame and frame rate. This is the case when the temporal controller is set to the Animation mode. In this case the
   animated markers will follow the temporal controller animation, e.g. pausing when the animation is paused, advancing frames
   with the animation, etc. The map will also be redrawn using the frame rate set for the temporal animation.

This mode also applies when exporting an animation from the temporal controller.

It's also the mode used when a plugin specifically sets the frame rate and current frame QgsMapSettings properties, so
e.g. @timlinux's QGIS Animation Workbench plugin will dictate the marker animation frame to render.

2. If the map is NOT considered an animation (i.e. it's just a plain old normal QGIS project), then the frame to render will be based on the current timestamp alone.

Markers will be animated when their corresponding layer is set to a temporal mode, and a temporal animation is playing.

Showcase

Animated marker in a standard map, no temporal animation settings

Animated marker when used with temporal controller in animation mode

[github-actions]

@nyalldawson
This pull request has been tagged as requiring documentation.

A documentation ticket will be opened at https://github.com/qgis/QGIS-Documentation when this PR is merged.

Please update the description (not the comments) with helpful description and screenshot to help the work from documentors.
Also, any commit having [needs-doc] or [Needs Documentation] in will see its message pushed to the issue, so please be as verbose as you can.

Thank you!

[timlinux]

Thanks so much for this awesome PR!

[timlinux]

Tested here, works really great!

(Line artifact is from peek, not your code)

[nirvn]

Tested, it is sweeeeet. I love the flawless animation integration in non-temporal (i.e. plain old canvas) context. Nicely done.

Haven't looked at the code yet, but my quick testing pointed out at a need to have a selected state rendering here (I think it should be easy to copy paste what we have for the raster marker et al)

[nyalldawson]

@nirvn

Haven't looked at the code yet, but my quick testing pointed out at a need to have a selected state rendering here (I think it should be easy to copy paste what we have for the raster marker et al)

That's already implemented:

[nyalldawson]

(unrelated test failure)

[nirvn]

I'll give it a try m again. Maybe my large animation marker had me hit too far away from the small hit area for point features.

[nirvn]

@nyalldawson , my bad, it does work:

Also, working flawlessly out of the box with QField:

[nirvn]

@nyalldawson , brilliant stuff, I ❤️ this contribution to QGIS. And thanks @timlinux for being such a great muse 😉

[nyalldawson]

Thanks for the review @nirvn!

Also, working flawlessly out of the box with QField:

I noticed that you've got the flashing "redraw" indicator happening here. If you want to avoid that you need to check the "deferredUpdate" flag when QgsMapLayer::repaintRequested is emitted, and if it's true then the redraw should happen "silently".

[github-actions]

@nyalldawson
A documentation ticket has been opened at qgis/QGIS-Documentation#7468
It is your responsibility to visit this ticket and add as much detail as possible for the documentation team to correctly document this change.
Thank you!