RFR: 8314820: Unify Screen adapter ordinal logic

[Lukasz Kostyra]

On Wed, 17 Dec 2025 11:02:54 GMT, Marius Hanl <mhanl at openjdk.org> wrote:

> > One thought nagged me during the review: why do we keep the ordinal (an index) when we could, in theory, keep a reference to the object? Is there a potential for misalignment, perhaps a transient one?
> 
> My guess: Because the purpose is to be an Identifier (ID) only, so that a Screen can be later mapped to a Pipeline, if needed. The `MTLPipeline` does not need that, but e.g. `D3DPipeline` does. I guess using an object therefore could be possible, but makes sense only for some pipelines still.

That would be my guess too. In D3D9 there's a "lost device" event which applications need to handle properly - whenever ex. a screen resolution changes, a screen gets (un)plugged, the window gets minimized/restored, or even when the fullscreen app loses keyboard focus. When D3D9 loses the Device for any reason the rendering calls are silently ignored and runtime returns an appropriate error code - application needs to first "reset" the device and then recreate all resources (especially resources stored in VRAM).

I would suspect that a D3D9 device reset can have a possibility of changing how the system enumerates the screen, so we might need to be able to re-identify the screens in order to re-tie the respective Resource Factories. I wasn't there when this was written, but an ordinal seems to be the easiest way to go about it. Other backends probably don't really use it since they don't have a scenario like this.

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PR Comment: https://git.openjdk.org/jfx/pull/2009#issuecomment-3665006186