Film strip

A carousel as a strip of film in a machined viewer. The frames run behind a gate lit from behind, with sprocket holes along both edges, and the frames either side wait under a smoked cover. It moves a frame at a time and settles as each one registers. Turn the thumbwheel, press the keys or swipe the film itself: underneath it is a native scroller with a snap point at every frame.

Turn the thumbwheel, scroll on it, press the keys or swipe the film. Tab to the film and use the arrow keys, Home and End. Click a dim frame to bring it into the gate.

• It is a region with aria-roledescription="carousel", named by its label, and each frame is a group named “4 of 12: Canary”, so a screen reader hears where it is and what the frame is before anything on it.
• When a frame comes to rest, the same words go to a polite live region. While the thumbwheel has focus they are left to the slider, which speaks its own value, so nothing is said twice.
• Underneath is a native scroller with a snap point at every frame. Without the script a swipe, a trackpad and the arrow keys still move it a frame at a time, and the film is a tab stop for that.
• The thumbwheel is a slider with aria-valuetext and the keys are real buttons named “Previous frame” and “Next frame”. At an end the key is aria-disabled, so focus is never dropped.
• The LCD counter is a second signal for the eye and is hidden from assistive technology.
• A frame beside the gate takes one click to come in before anything on it acts.
• With reduced motion the film goes straight to the frame, with no glide and no settle.