Techs can change the player poster only once

[ghost]

Description

New techs are unable to integrate into the poster lifecycle and can switch a poster only once which triggers a posterchange event.

Example

The region of code that seems to be responsible is handleTechPosterChange_

Steps to reproduce

Explain in detail the exact steps necessary to reproduce the issue.

1. Create a tech that triggers a posterchange event and changes the poster
2. Implement the poster method on the new tech
3. Change the poster and trigger a posterchange event

Results

Expected

A new poster

Actual

The same old poster.

Error output

None

Additional Information

Please include any additional information necessary here. Including the following:

versions

videojs

5 + 6, most likely older versions as well

browsers

firefox, chrome,

OSes

tested on Kubuntu 16.04

plugins

None

[gkatsev]

Interesting. That's definitely an unintended side-effect of the code. The idea was that if the user sets a poster the tech shouldn't override it but the way that the code accepts a poster from the tech means that it only gets set once. It totally makes sense for the techs to be able to change their poster as much as possible assuming we don't change the behavior that a user-set poster isn't overridden. Would you be able to and interested in submitting a fix?
Thanks.

[ghost]

Yeah, sure. I wouldn't mind. There'd be a few things to clear up first, since I see a few possibilities here:

Introduce techs that have the power to override any poster

Could add a static field to the tech that is checked in the posterchange handler e.g

if( (!this.poster_ || this.tech_.canOverridePoster) && this.tech_.poster ){
  this.poster_ = this.tech_.poster();
  this.trigger('posterchange'); 
}

Introduce boolean option in player to allow techs to override the poster

if( (!this.poster_ || this.options_.techCanOverridePoster) && this.tech_.poster ){
  this.poster_ = this.tech_.poster();
  this.trigger('posterchange'); 
}

Track when poster has been set by player.setPoster

This could be done with a boolean in the player.setPoster and setting the poster to an empty string will allow techs to override the poster once again. Maybe setting it to false will indicate that it should remain unset.

---

All of these might still require to track when the poster was set by the tech, in order to clear the poster when the tech is disposed of.

That's what comes to mind. Thoughts?

[gkatsev]

I'd be inclined to leave out techs that can override the poster for now, at least until we see people asking for that. Unless you're asking for it? :)
Having an option like techCanOverridePoster sounds good to me. Thoughts @videojs/core-committers?
And yeah, you're right, we probably need to track whether the poster was set via the tech or by the user.

[ldayananda]

The option techCanOverridePoster seems like the best choice to me