Package limn.scene.layout

Class Expanded

java.lang.Object

limn.scene.Widget

limn.scene.layout.Expanded

public final class Expanded
extends Widget

Flex wrapper: inside a Column/Row it receives a share of the leftover main-axis space proportional to flex. Without a child it is a spacer(int): pure flexible whitespace.

The share is a tight constraint, so it overrides what the child asked for. A flex child is measured with its main axis pinned to the share (minimum and maximum both equal to it), and the size the child returns from its own onMeasure is discarded on that axis. A control that measured itself at 116 pt because that is what its chrome and its widest value need will be handed 35 pt in a crowded row and will paint at 35, one part on top of another. That is the container doing as it was told: nothing in the layout protocol lets a widget refuse.

atLeast(float) is how a call site refuses on the child's behalf. It is opt-in per call site rather than a default, because the right floor is not a property of the widget class: a caption that ellipsises wants to be squeezed (that is what the ellipsis is for) and a stepper with a fixed chrome width does not, and the same widget can be either one depending on the row it is in.

Method Summary

Modifier and Type	Method	Description
Expanded	atLeast(float points)	Declares a main-axis floor, in logical points: this child is never given less than points, however little the weighted split would leave it.
int	flex()	This child's share weight.
float	minMain()
static Expanded	of(Widget child)	An equal share of the leftover space: flex of 1.
static Expanded	of(Widget child, int flex)	Gives child a share of the leftover space proportional to flex.
protected void	onLayout()	Containers position children here (measure + Widget.layoutBox(float, float, float, float) per child).
protected Size	onMeasure(Constraints constraints)	Reports the size this widget wants within constraints.
static Expanded	spacer(int flex)	Flexible empty space.

Methods inherited from class limn.scene.Widget

acceptsTextInput, add, baselineOffset, baselineOffsetOf, caretRect, children, clipboard, clipsChildren, controlSize, cursor, declaredControlSize, declaredLayoutDirection, declaredLocale, focusArrivedByTraversal, height, hitTest, imageCursor, invalidate, invalidate, isEnabled, isFocusable, isFocused, isShowing, isVisible, layoutBox, layoutDirection, locale, localToSceneX, localToSceneY, markNeedsContainedLayout, markNeedsLayout, measure, moveChild, neutralBase, onAttached, onCharTyped, onDetached, onFileDrop, onFocusGained, onFocusLost, onKeyEvent, onMouseEvent, onPaint, onPaintOverlay, onPreedit, overlayPassesPointer, paintChildren, paintOutset, paintWidget, parent, remove, requestFocus, revealInView, scene, sceneToLocalX, sceneToLocalY, setControlSize, setCursor, setEnabled, setFocusable, setImageCursor, setInheritanceHost, setLayoutDirection, setLocale, setTooltip, setTooltip, setVisible, shapeText, textRuler, tooltip, width, x, y

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

of

public static Expanded of(Widget child,
 int flex)

Gives child a share of the leftover space proportional to flex.

of

public static Expanded of(Widget child)

An equal share of the leftover space: flex of 1.

spacer

public static Expanded spacer(int flex)

Flexible empty space.

flex

public int flex()

This child's share weight.

atLeast

public Expanded atLeast(float points)

Declares a main-axis floor, in logical points: this child is never given less than points, however little the weighted split would leave it. Chains after of(limn.scene.Widget, int). The default is 0: no floor, and the distribution is the plain weighted one.

The container satisfies floors before weight. A child whose share would fall under its floor is frozen at the floor and drops out of the split; whatever is left is re-divided among the others, which can push another one under its own floor, so this repeats until nothing is under. Siblings without floors absorb the whole loss, which is the point: a floored stepper beside an ellipsising label keeps its chrome and the label gives up the points.

Floors that do not fit overflow the container. When they add up to more than there is room for, every child still gets its floor and the row is over-subscribed; children paint past the container's edge. This is the same outcome a row of too-wide fixed children has today: a Flex does not clip and does not wrap, so an over-subscribed row is visibly over-subscribed rather than silently truncated. Declare floors that fit, or give the container more room.

Negative values clamp to 0. UI thread only.

minMain

public float minMain()

Returns:

the declared main-axis floor in points, 0 when none was set

onMeasure

protected Size onMeasure(Constraints constraints)

Description copied from class: Widget

Reports the size this widget wants within constraints. Called once per layout pass, and the result is cached against the constraints and the resolved axes (size step, layout direction, locale), so it must be a pure function of them and of this widget's own state.

Resolve the ControlSize and the LayoutDirection once each here and thread them down; never read either in a constructor. The locale needs no threading: it is in scope, and I18n.locale() answers it wherever text is resolved.

Specified by:

onMeasure in class Widget

onLayout

protected void onLayout()

Description copied from class: Widget

Containers position children here (measure + Widget.layoutBox(float, float, float, float) per child).

Overrides:

onLayout in class Widget