feat(ui): Add configurable rates

[nbcl]

The present pull request aims to provide a solution to #3443 (How to Customise PlayBackRate or Fast_Forward rate) by adding optional custom rates for playback, fast forward and rewind.

Fixes: #3443

Example

How to preview

Initialize the client with a config that contains playback_rate, fast_forward and rewind in the controlPanelElements and select a list of rates for playbackRates, fastForwardRates and rewindRates.

const config = {
 'controlPanelElements': ['playback_rate', 'fast_forward', 'rewind'],
 'playbackRates': [0.5, 1, 1.5, 2, 4.321],
 'fastForwardRates': [2, 4, 8, 1],
 'rewindRates': [-1, -2, -4, -8],
}
ui.configure(config);

Changelog

docs/tutorials/ui-customization.md

Adds a brief description and example for the playbackRates, fastForwardRates and rewindRates configuration.

ui/externs/ui.js

playbackRates, fastForwardRates and rewindRates are added as configurable options in the UI.

ui/fast_forward_button.js

this.fastForwardRates_ is added to load the configured rates. On every click, the next rate in the array is selected until the end is reached, where the rate is set back to the initial value at this.fastForwardRates_[0].

ui/playback_rate_selection.js

The original this.playbackRates_ map is built through a configurable array of numbers (playbackRates) and which also generates the text value ('1.25x' for 1.25).

ui/rewind_button.js

this.rewindRates_ is added to load the configured rates. On every click, the next rate in the array is selected until the end is reached, where the rate is set back to the initial value at this.rewindRates_[0].

ui/ui.js

Adds default values for playbackRates, fastForwardRates and rewindRates.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code
• I have made the corresponding changes to the documentation
• My changes generate no new warnings
• I have run ./build/all.py and the build passes
• I have run ./build/test.py and all tests pass

[michellezhuogg]

Good job! Thank you!

[shaka-bot]

All tests passed!