UXMetrics

UXMetrics gives the standard control sizes. Without shared sizes, each platform renders a button at its own size, and a UI laid out on one realm’s rows overflows another’s. A single global table does not work either, because a desktop row and a touch target are different sizes. The standards therefore adapt on one axis: the form factor. Desktop rows sit on the classic 28px basis. The device realm sits on the 44pt touch target (Apple’s floor; Android’s 48dp guidance rounds to the same value in neutral units).

The table is one side of a two-sided contract. The drivers keep the other side: a control fills the frame it is given and never exceeds it. Theme minimums are clamped where the platform allows (Android’s setMinHeight(0), GTK’s CSS floors dropped at boot). The few controls with a fixed intrinsic size (UIStepper, UISwitch) are centred in their frame, and their standard size here is large enough to hold them.

Out-of-bounds areas (the notch, the status bar, the gesture bar) are not in this table. The platform handles them through window positioning: a toolkit window at y=0 already sits in the safe area on every backend, and boot() reports the usable screen.

#use <UXKit>

Overview

// a form row, sized to the current realm's standards:
UXButton* ok = new UXButton();
ok.setTitle((u8*)"OK");
content.addSubview(ok, UXMetrics.stdFrame((i32)UXKindButton, 8, y, 0));
y = y + UXMetrics.stdHeight((i32)UXKindButton) + UXMetrics.rowSpacing();

The pure ...For(kind, ff) forms are the unit-testable source of the values (make metrics checks both realms without opening a window). The short forms read the live driver’s formFactorClass().

The standards

kind	desktop	device	note
Button	28	44	the touch-target floor
Field	24	36
Label	16	20
Checkbox / Radio	20	32	device row holds a UISwitch
Slider	20	32
Popup	26	36
Stepper	26	32	device min-width 96 holds a UIStepper
Progress	12	8	the idioms invert: bar vs line
Segmented	26	32

Topics

Sizes · stdHeight · minWidth · stdFrame Spacing · rowSpacing · gutter The pure forms · stdHeightFor · minWidthFor

stdHeight

static i32 stdHeight(i32 kind)

The standard height for a control kind on the booted driver’s realm.

minWidth

static i32 minWidth(i32 kind)

The minimum comfortable width, which stdFrame uses when no width is given.

stdFrame

static UXRect stdFrame(i32 kind, i32 x, i32 y, i32 w)

The standard frame for a kind at a position, in one call. w <= 0 means “the minimum comfortable width”.

rowSpacing

static i32 rowSpacing(void)

The vertical gap that makes a column of standard controls read as a form: 8 on desktop, 12 on device.

gutter

static i32 gutter(void)

The margin from the window edge: 12 on desktop, 16 on device.

stdHeightFor

static i32 stdHeightFor(i32 kind, i32 ff)

The pure form: the same answer with the form factor passed in, testable without a driver. ff is a UX_FORM_* value.

minWidthFor

static i32 minWidthFor(i32 kind, i32 ff)

The pure width form.