UGTK / Toolkit / Ui Module / Screen Chooser System Completed

Screen Chooser System

Summary

ScreenChooser watches the screen orientation and fires UnityEvents when it changes, so a layout can rearrange itself without a single line of code. It reports two different things, and knowing the difference is the whole point of the module:

logical orientation — what the device says (Portrait, PortraitUpsideDown, LandscapeLeft, LandscapeRight);
visual orientation — what the window actually looks like (width vs height), which is the one that matters on desktop, in the editor and in a resizable WebGL canvas, where the device orientation is Unknown or never changes.

Modules Dependencies

None. Only UnityEngine (Screen.orientation, Screen.width/height) and UnityEvents.

Setup

Drop the ScreenChooser prefab into the scene — a GameObject carrying the component with all six events ready to be wired. Or add the component to any GameObject that lives as long as the layout it drives.

There is no GIF for this module: the effect is a device rotation, which is neither visible nor reproducible inside the editor window.

How To Use

Wire the events in the inspector:

Logical Orientation Events — On Portrait, On Portrait Upside Down, On Landscape Left, On Landscape Right. These follow Screen.orientation, so they are meaningful on phones and tablets.

Visual Orientation Events — On Visual Portrait, On Visual Landscape. These follow Screen.height > Screen.width. This is the pair you want on desktop, WebGL and in the editor, where the logical orientation never changes.

Settings — Continuous Update (off by default): when on, the events fire at every poll tick (five times a second) instead of only when the orientation changes. Turn it on only for something that must be driven continuously; leave it off for normal layout switching, or your listeners run 5× per second forever.

Good to know:

It fires once on Start with the current orientation, so a listener that arranges the layout is called at least once without any rotation.
Polling is every 0.2 s in a coroutine — a rotation can take up to 200 ms to be picked up. That is imperceptible for a layout switch, but do not use it to drive an animation.
The two families are independent: LandscapeLeft and LandscapeRight both raise OnVisualLandscape. If you only care about "is it wide or tall", use the visual pair and ignore the logical one.
The class is called ScreenChooser, without the Mn_ prefix, even though the file is Mn_ScreenChooser.cs: use GetComponent<ScreenChooser>().

Testing Scene

Open Debug/ScreenChooserScene.unity. It holds a Canvas, an EventSystem and the ScreenChooser prefab. A desktop editor cannot be physically rotated, so the component's inspector carries an Editor Test Tools block that stands in for a device.

The block has two halves:

What Unity reports — Screen.orientation and the shape derived from width versus height. These are the values the component itself watches, and they update as you change the Game view's aspect ratio. It is worth checking them before blaming the component: on a desktop editor Screen.orientation often reports something a phone never would.
Visual events and Precise events — six buttons that raise the events by hand, so a layout can be finished and tested without a device in your hand.

Wire your layout to the visual pair, OnVisualPortrait and OnVisualLandscape. They are derived from width versus height, which is the question a layout actually asks. The precise four — OnPortrait, OnPortraitUpsideDown, OnLandscapeLeft, OnLandscapeRight — matter only when the exact rotation does, a compass or a camera overlay for instance. Driving a layout from them means handling upside-down portrait separately for no reason, and forgetting it is a bug that only shows up on a device someone happens to hold the wrong way round.

Technical Info

Path	Content
`Scripts/Runtime/Mn_ScreenChooser.cs`	The whole system: the `ScreenChooser` component, the 0.2 s polling coroutine, the logical and visual event dispatch
`Prefabs/ScreenChooser.prefab`	GameObject with the component ready to wire

Public members: OnPortrait, OnPortraitUpsideDown, OnLandscapeLeft, OnLandscapeRight, OnVisualPortrait, OnVisualLandscape, continuousUpdate.