Features

Constraint Layout Improvements

Constraints got a major round of work in this release, with new building blocks and a lot of correctness and performance fixes in ConstraintLayout and the Solver.

• prefers suggests a value for a constraint property without enforcing it or limiting the property's range. It supports Strength.
• lerp interpolates between a number and an expression, or between two expressions. ColorPicker now uses it.
• min/max constraint functions now use n + 1 constraints instead of 2n, and use Weak strength.
• readonly replaces the previous snapshot-only behavior, and ideal width/height/size values are now supported in constraint layouts.
• Constraints now have a position property that maps to top/left.
• ConstraintLayout has new parentWidthPreservation and parentHeightPreservation properties that control how strongly parents preserve their size during preferredSize calls.
• ConstraintLayoutImpl now enforces the parent size on layout. It uses suggestValue when a preferred value changes instead of removing and re-adding the constraint.
• center helpers now treat the item's width/height as readonly.

AnnotatedString

StyledText is now AnnotatedString, and the feature set has grown.

• Segments can be marked "selectable", which enables automatic text selection on platforms that support it.
• AnnotatedString.Annotation supports URLs, and new link extension methods create URL sections. This works in the Browser as well.
• TextDecoration.Line can be used directly in the AnnotatedString DSL.

Breaking Changes

• StyledText → AnnotatedString
• StyledTextVisualizer → AnnotatedStringVisualizer
• Slider "tick(s)" → "mark(s)" throughout the slider APIs
• Constraint hint → prefers
• readOnly replaced with value in constraint Expression, Position, Area and Edges
• BasicTabbedPanelBehavior now takes selected/unselected Colors and no longer takes selectedColorMapper
• ScrollPanel's contentWidthConstraints and contentHeightConstraints replaced by a single contentConstraints property
• Presenter.present and Presenter.distanceToNext no longer take an items parameter. Use the new Carousel.item extension API instead.
• Size.coerceInAspect now takes a target Size instead of a min and max
• TextMetrics no longer has a default lineSpacing
• Most Rectangle methods moved to extensions. Add the extension imports where needed.
• GridPanel now takes a GridPanelBehavior
• Removed the deprecated Kodein binding and other old deprecations

APIs

• General

  • Positionable has new properties for more ergonomic layout logic, including assume, which lets a Layout set size/min/max all at once
  • Polygon now has area and centroid properties
  • New ConvexPolygon.centroid extension property
  • New Size.coerceInAspect method that retains aspect ratio while coercing a Size into a min/max
  • Carousel.PresentedItem now has an idealSize method
  • New allNext and allPrevious methods for Presenter.Position that return iterators to the items after and before the current one
  • SlicerPresenter now takes a cutRelativeTo parameter to change how slices are constructed
  • TreeTableBehavior now has explicit header and footer cell generators for the tree column
  • BasicSliderBehavior and BasicRangeSliderBehavior now allow overriding their groove inset ratio
  • Label now allows disabling auto size suggestion
  • Resizer now notifies of changes to the bounds it suggests for its View
  • New vararg builder for SimpleMutableListModel
  • Methods that guarded against incorrect arity usage are replaced by varargs, with deprecated overloads in their place

• Browser

  • New URL support within AnnotatedString

Fixes | Improvements

• General

  • Constraint layout failures when parent constraints change based on limits imposed by a grandparent
  • Solver.updateConstant not working for non-Required strength
  • Solver not tracking and cleaning up negative guards
  • Solver range computation, isUnderConstrained accuracy, and readonly/ideal handling
  • Solver now clamps values very close to 0 to 0
  • Constraint hashCode changing after being added to a context, or going stale when strength is updated
  • Constraint updates across layouts now track only adds/removes instead of a list diff
  • Constraint properties not updating when only modified by a single prefers call
  • Bugs with offset constraints and internal constraint variable equality checks
  • Layout bugs in List, GridPanel, FlexLayout, Table, Carousel, PopupManager, InteractiveLayout, ListItem, SplitPanel and ColorPicker
  • ListLayout now lets items take any size within constraints instead of bounding them to their ideal size
  • Table contents not extending to the parent size when the ideal size was smaller
  • Layout issues in BasicTabbedPanelBehavior and TreeRow, plus a more accurate internal rendering of BasicTabbedPanelBehavior
  • BasicTreeTableBehavior now trims the header/footer tree column cell region so it aligns with the icon width
  • TableBehavior and TreeTableBehavior column renderers now get expanded canvases that stretch to the bottom of the table
  • Visual tweaks and preferred-size handling for BasicSpinButtonBehavior, BasicMutableSpinButtonBehavior and BasicButtonBehavior
  • View giving a stale current size when calling Layout.preferredSize
  • View resetting its children incorrectly during layout, and calculating preferred size changing children's bounds
  • Top-level Views not being laid out when their preferred size changed
  • Size not being set properly during layout, and Display.relayout not updating positionables properly
  • View.visibilityChanged firing even when set to the same value
  • Better View sync when bounds are suggested during render/bounds syncing
  • Label issues with preferredSize
  • Removed the phantom View used by ScrollPanel in its internal layout
  • AnimatingTabContainer updating tab locations a frame early, which looked like phantom pointer events
  • paused event firing incorrectly for grouped animations
  • DampedTransitioner animation accuracy
  • Carousel not performing subsequent updates if its model was empty on the first one
  • Carousel render issue when an item's clipPath is used
  • SlicerPresenter not calculating the next item's size correctly
  • Concurrent modification in the render pipeline
  • List selection allowing items outside firstSelectable and lastSelectable
  • Vector3D.as2d() still returning a 3D vector
  • Rectangle constructor not allowing defaults
  • TreeColumnRow default
  • Constraint usage in the switchList form control
  • Conflicting overloads in Vector2D
  • Misspelled API names

• Browser

  • Native ScrollPanel behavior now disables scrolling when the panel is disabled
  • Apps nested within DOM elements now lazy load when the element has a valid offsetParent
  • Native control detection issues that regressed drag-and-drop and broke key event handling
  • Regression in drag-drop visualization
  • NativeScrollPanel incorrectly discarding elements for old content it no longer contains
  • Canvas clip regions being clipped to the canvas bounds, limiting how large they could be
  • TextMetricsImpl interfering with view ordering because it adds elements to the DOM
  • TextMetricsImpl not cleaning up its cached node for measuring wrapped text
  • Sub-pixel element measurement
  • Text measurement being incorrect when a null Font was provided
  • Font not being reset on reused elements
  • Default line-height not being used correctly, which caused text clipping
  • Text width measurement for AnnotatedString
  • First Display size change being missed in some cases
  • Concurrent modification bug in SchedulerImpl
  • WASM casting bug
  • Issue with incorrect default lineHeight

• Desktop

  • Updated deprecated needRedraw calls for Skiko

Performance

• General

  • Various performance improvements across the framework, some more significant for Browser
  • Fewer constraints needed for min and max (2n → n + 1)
  • Less reflection in ConstraintLayoutImpl, Solver and other hot spots, which matters most for browser targets
  • Less object creation in Solver by using forEach directly on maps
  • Less object creation within Rectangle and Size
  • Explicit Double versions of functions that previously took Number
  • View only requests layout for its parent when its layout size differs from its current size while using layout-based preferredSize, which cuts duplicate preferred-size calls
  • Less overhead in View layout and preferred-size calls
  • RenderManagerImpl uses sets more efficiently, along with other changes that improve render performance
  • LinearPresenter no longer accesses items unnecessarily
  • basicVerticalListBehavior uses a ColorPaint instead of a PatternPaint when the even and odd colors are the same
  • Constraint exceptions are no longer thrown for some cases

• Browser

  • Replaced the box-sizing: inherit CSS style with box-sizing: border-box, which has the same effect without referencing parent nodes
  • Replaced the DisplayImpl.layout delegate with a simple property
  • AnimationSchedulerImpl avoids multiple requestAnimationFrame calls in a single frame
  • Better font serialization caching
  • TextMetricsImpl uses the canvas more heavily when supported
  • TextFactoryImpl reuses more elements
  • PathMetricsImpl minimizes element add/remove cycles when measuring paths
  • FillHandler no longer clears children of SVGPatternElement, since they can be reused
  • Less use of observable in Label to avoid reflection
  • Check-before-set in DOM operations
  • viewPortOffset is only checked in Safari, since it's in a hot path

Build

• Re-added Kover through a convention plugin
• Added a convention plugin to handle publishing
• Moved Dokka external link config for Measured into the convention plugin
• Migrated to the Dokka 2 API
• Fixed a Gradle dependency issue with test-fixture
• Fixed compiler issues caused by formerly lax code
• Fixed nmcp publication logic

Tests

• Expanded View test coverage
• New Solver and InteractiveLayout unit tests
• Fixed Solver, SchedulerImpl and other unit tests

Versions

• Kotlin -> 2.4.21
• Gradle -> 9.5.0
• Dokka -> 2.1.0
• JUnit -> 5.10.1
• Measured -> 0.5.0
• ncp -> 1.6.2