Mobile UI

What makes ClassicUO's mouse-and-keyboard interface playable with fingers, and how the client decides which defaults a platform gets. Sources: docs\ui\mobile_playability.md (the verified / written / missing table), docs\ui\grid_container.md, src\Configuration\PlatformDefaults.cs, and the commit messages of the work/ui chain, each of which names what was seen on the device.

Per-platform defaults

One table in Configuration\PlatformDefaults.cs holds every profile default that differs by platform. Desktop has one set (version 5: a full-size world and wheel zoom); everything else on the desktop is exactly upstream's. Mobile gets a full-size borderless world, pinch zoom kept, large and scaled containers, grid containers, fitted container placement and the low-power background. Web gets a full-size world and wheel zoom. The platform comes from OS.HasFeature (mobile, web); UO_PROFILE_PLATFORM overrides it on the desktop for checks.

Profile versions and migration

Profile.ProfileVersion records which table a profile has seen. Each entry in the table carries a since version. When a profile is loaded that is below the current version (a new one, or one saved before an entry existed), every field that still holds upstream's default takes the platform's value; a field the player changed is kept. The player never has their own choice overwritten.

Version	Added
1	The table itself: window, zoom and container sizes for Mobile and Web.
2	FitContainerPlacement on Mobile.
3	GridContainers on Mobile.
4	The canvas background entry, taken by the background branch (see ADR-0016).
5	Desktop: the world fills the window and the wheel zooms, as on Mobile and Web, instead of upstream's 600x480 world in the corner of a large window. Unticking "Game window full size" under Options gives the smaller, movable world back.
6	CanvasBackgroundLowPower on Mobile and Web (ADR-0016).

Migration from 2 to 3 was verified on the device (commit "GridContainerGump: containers as a grid"), and to 6 by the canvas background work.

The touch layer

src\Input\Touch\TouchInput.cs translates Godot's screen touch, drag and magnify events into the mouse events GodotInput already consumes, so the ported game code sees a mouse. Off the touch layer, the desktop path is unchanged; every hook into ported code is marked PORT DEVIATION (GUO).

Gesture	Becomes
Tap	Left click
Second tap	The game's own double click
Hold on the world	Held right button: walk, then run
Hold on an item	Held left button: pick up, then drag
Long press	Right click
Pinch	Ctrl + wheel steps (zoom); accumulated from magnify gestures
Tap on the gump bar	The top-bar action

Verified on the device: login by touch alone, hold-to-walk, pinch in and out, drag, split and drop into the bank, double-tap use (commits "Android: fullscreen, soft keyboard..." and "GridContainerGump..."). On the desktop, launchers\dev\touch_probe.bat drives synthetic fingers through the layer and checks 18 gestures against the shard; --touch enables the layer on the desktop and --touch-trace logs each gesture decision.

The touch bar

TouchGumpBar.cs is a CanvasLayer overlay along the bottom, drawn with the top bar's own button art and clilocs: six finger-sized actions. While a target cursor is up it shows Self and Cancel so a spell or a bandage can be aimed and a target can be abandoned without a keyboard (commit "Touch bar: Self and Cancel while a target cursor is up").

The soft keyboard

A tap on a text field raises the soft keyboard and slides the field's root gump up by what the keyboard covers; the world gump is never moved. The account field asks for the e-mail keyboard and the password field for the password keyboard, the two types an IME must not autocorrect in.

Grid inventory

GridContainerGump shows a container as a grid of finger-sized slots instead of upstream's free-placed items. It is a new gump, not a ContainerGump subclass: OpenContainer keeps upstream's classic path and then calls GridContainerGump.ReplaceClassic, the one upstream hunk. The grid polls its container's contents, saves as GumpType.Container so gumps.xml restores it through the classic path, pages when it would exceed the screen height, and has a filter field, a sort toggle and a Classic button. Slots call the same GameActions as ItemGump.

Options, in the Containers section: "Open containers as a grid of slots" (GridContainers), a slot size slider from 32 to 80 (GridContainerSlotSize, default 44) and the fitted placement checkbox. Changing the slot size rebuilds open grids. The grid takes as many columns (three to six) as fit half the client width so two containers still sit side by side.

Container placement on a phone

Upstream cascades containers from the top left, which puts the backpack on the character. With FitContainerPlacement on, ContainerPlacement keeps a remembered spot unless it covers the character, and otherwise picks the right-most, top-most free spot inside the client area, below the top bar and above the touch bar, covering the least of the character and the other open gumps. Gumps restored from gumps.xml at login are moved off the character the same way. Off on the desktop, and off whenever "override container location" is set.

The screen scale

On a phone the touch layer sets the client's whole-number ScreenScale to fit the display, dividing the OS scale out, without touching the global setting. Options writes the screen zoom back only when its slider moved, so pressing Apply for something else does not shrink the UI (commit "Options: apply the screen zoom only when its slider moved").

What is still missing

docs\ui\mobile_playability.md keeps the table of every interaction a player needs, marked verified, written or missing. Read it before claiming a phone is playable; some rows have moved since it was written (target cancelling is now on the touch bar, but the table still says missing).