ltk/CHANGELOG.md

Changelog

All notable changes to ltk are documented here. The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

Unreleased

Added

• Per-canvas pixel density — Canvas::set_density pins a canvas (and the sub-canvases derived from it) to its own density factor for Length::dp resolution, overriding the process set_density global; Canvas::density reads the effective value. New Canvas::resolve_geom / Canvas::resolve_font resolve an explicit Length in geometry / font space with the canvas' density — widgets now route caller-supplied lengths through them, so a dp override follows the canvas it draws on. The hook for surfaces on outputs whose DPI differs from the process-wide one (an overlay on a second monitor, an embedder with several UiSurfaces).

• Length::resolve_with_density — Length::resolve with an explicit density for LengthBase::Dp, instead of the process density().

• docs/backends.md — the canonical software/GLES capability matrix: what renders identically, what degrades gracefully on software (gradients, shadows, backdrop blur, bottom fade) and what is GPU-only, replacing per-method rustdoc archaeology. Linked from README, onboarding and the architecture known-gaps list.

• Clippy in CI — the test job lints with cargo clippy --workspace --all-targets --features test-support -- -D warnings; make clippy mirrors the invocation locally.

• ListItem::trailing_icon( rgba, w, h ) — right-aligned icon slot (disclosure arrow) drawn at TRAILING_ICON_SIZE (21 px) and vertically centered, alongside the existing leading icon. Coexists with trailing text, which shifts to the icon's left. Symbolic icons should be pre-tinted by the caller (tint_symbolic), matching the leading-icon contract.

• ListItem::pad_h( impl Into<Length> ) — per-item override of the horizontal inset between the row edge and its content; without it the theme default (16 px) applies.

• Row::align_top() / Row::fill_height() — pin children to the row's top edge instead of the default vertical centering, or stretch every non-spacer child to the row's inner height (the row itself is still sized by its tallest child), for siblings whose natural heights differ by a few font-metric pixels.

• App::window_resizable() — return false to keep the min_size == max_size pin from window_size_hint for the toplevel's lifetime, declaring a fixed-size window compositors must not resize. Default true.

• App::claims_raw_touch() — return true to receive the primary finger through the raw on_touch_down / move / up stream, bypassing the built-in single-slot gesture machine entirely (widget presses, taps and swipes stop working on touch), for surfaces that are one self-contained input consumer such as an embedded WebView or a game canvas.

• Responsive sizing system with two selectable modes via WidgetScaling (Fluid / Physical; set_widget_scaling / widget_scaling, default Fluid). New Length constructors — orient( portrait, landscape ) (a percentage of the width in portrait, of the height in landscape), fluid( px ) (surface-proportional, calibrated against set_fluid_reference and bounded by FLUID_MIN / FLUID_MAX), dp( px ) (constant physical size scaled by set_density / density), and widget( px ) (picks fluid or dp per the active mode). Canvas::geom_px (geometry, physical layout space) and Canvas::font_px (font, bridging the logical / physical split per mode) give widgets and apps one resolution path.

• Button::font_size / height / width and TextEdit::height builders, all impl Into<Length>, so control boxes scale with the surface. Text::line_height( mult ) opens the gap between wrapped lines. Separator::pad_v (with Length::px( 0.0 ) for a flush divider).

• Performance guardrails: opt-in diagnostics via LTK_PERF_WARN=1 (stuck animation, sustained software-render animation, low poll_interval) and a ~30 Hz software-animation cap overridable with App::cap_software_animation.

• grid_min_cell( width ) and WrapGrid::max_columns( n ) — adaptive grid: the column count is derived at layout time from the available width so every cell is at least width wide (any Length; never fewer than one column), re-derived on every resize; max_columns caps the count so cells grow instead of multiplying on wide surfaces. grid( n ) keeps the fixed-count behaviour.

• Vertical flex: flex( child ) now distributes leftover height inside a Column, mirroring its leftover-width behaviour in a Row — weights split the spare space between flex / spacer siblings, the child draws inside the allocated share, and it contributes zero to the column's natural height like a weight-only spacer.

• make stylecheck / scripts/style-check.sh — mechanical checks for the grep-verifiable subset of the style guide (tab indentation, spaces inside attribute brackets), wired into CI. The whole tree was normalized to pass (82 attribute sites).

• ltk::orientation() / viewport_size() / set_viewport_size and the Orientation enum — the runtime records the main surface's physical dimensions on every configure, so view() can branch a layout on portrait vs landscape (match ltk::orientation() { … }) without tracking on_resize by hand; the portrait/landscape rule matches Length::orient (square counts as portrait). Embedders driving core::UiSurface directly call set_viewport_size themselves. examples/clip_path.rs demonstrates it.

• test-support Cargo feature gates the test_support module so third-party builds never see it (ltk's own make test enables it).

Changed

• Length::dp now applies the density at resolution time, not at construction. The value carries its design pixels in a new LengthBase::Dp variant and resolve multiplies by the density in effect when it runs, so a set_density change takes effect on the next paint without rebuilding the view's lengths — previously a dp value was frozen to the density read when it was constructed. Behaviour is unchanged for code that sets density once at startup.
• The GLES image texture cache is now bounded to 32 MiB of estimated GPU memory with least-recently-drawn eviction (the in-use entry is never evicted). Previously it grew without limit for the canvas' lifetime, so a stream of distinct buffers (photo carousel, video thumbnails) could exhaust GPU memory.
• OverlaySpec::size is now ( Length, Length ) (was ( u32, u32 )), resolved against the main surface when the overlay is materialized; wrap existing sizes in Length::px( … ) for the old fixed behaviour.
• TextEdit::font_size, TextEdit::fixed_width and Separator::thickness now take impl Into<Length> (were f32), resolved like the button label (font space) / geometry space; the f32 sentinels are gone (f32 call sites still compile via Into<Length>).
• Dependency pins: fontdue = "=0.9.3" and ignore = "=0.4.23" are pinned exactly because newer releases require a rustc newer than the declared Rust 1.85 MSRV (Debian stable's toolchain).
• Renamed set_design_reference / design_reference → set_fluid_reference / fluid_reference. Length::dp changed meaning — it used to be a surface-proportional value, and that behaviour now lives on Length::fluid; dp is the constant-physical-size unit.
• Widget struct fields are now pub( crate ) (configured through builders), except the value / state types apps read or construct (Time, Date, ComboState).

Fixed

• Text inputs no longer insert mid-string when the value grows after focus. Focusing a text input pinned the cursor to a snapshot of value.len(); if the value kept growing without the widget seeing keystrokes (a field fed over IPC), the first normally-delivered key inserted at the stale position. The focus-time cursor is now an end-of-value sentinel that every consumer clamps to the current value length, collapsing to a concrete position on the first real keystroke or click.
• Single-line caret height now follows the text line. The caret spanned rect.height - 16, so a field taller than its text line grew an oversized caret; it now measures font_size + 4 and is vertically centered like the text, matching the multiline caret.
• Dialog action buttons no longer overflow the card on large surfaces. The card's width cap was a fixed 480 px while the stock buttons inside grow fluidly with the surface, so on windows past the design size the right-aligned action row ran off the card's right edge. Dialog::max_width now takes impl Into<Length> (f32 call sites keep compiling as fixed px) and the default is Length::fluid( 480.0 ), matching the buttons' scaling curve.
• App::on_pointer_axis now triggers a view rebuild and repaint. The raw axis hook (wheel/touchpad outside any ltk scroll viewport) fired the app callback but never requested a redraw, so state mutated there (a wheel-stepped carousel, an embedder-scrolled canvas) did not repaint until the next unrelated event.
• Dialog cards no longer double-pad their interior. The inner card column carried the column() 16 px default padding on top of the container's CARD_PADDING (24 px), giving the content 40 px of interior inset per side and squeezing the action row until its buttons clipped on narrow windows. The inner column is now flush and the interior inset is CARD_PADDING alone; the centering column's margin to the surface edges is explicit.
• Time-picker digits no longer overflow their boxes. The editable digit fields paired a fluid font (font_size_fluid) with a fixed 72 px box, so on any surface where the fluid font resolved larger than its design size the glyphs outgrew the field. The box is now Length::fluid( 72.0 ) — the same curve and clamp factors as the font, so both scale in lockstep.
• Content inside a scroll no longer renders smaller than the rest of the surface. Scroll viewports draw their child into a sub-canvas sized to the viewport rect, and fluid Length resolution (Canvas::geom_px / font_px — icon sizes, row heights, paddings, font sizes) resolved against that smaller canvas instead of the surface, shrinking everything inside any scroll by the width ratio (~13 % in a 360 px window with 24 px margins). Sub-canvases now inherit the root canvas's layout viewport (viewport_layout / viewport_logical), propagated through nested sub-canvases, so geometry resolves identically inside and outside offscreen content.

0.2.0 - 2026-06-25

This release adds the primitives an embedder needs to drive ltk as the render backend for a retained, externally-owned widget tree (for example projecting an Android view hierarchy onto an ltk surface). Each is kept general rather than tied to one consumer.

Added

• Canvas::set_clip_path — anti-aliased clipping to an arbitrary vector path (&[PathCmd]) on both backends. The software backend installs a tiny-skia coverage mask; the GLES backend captures the clipped draws into an offscreen layer and composites them back through an anti-aliased coverage mask. Complements the existing rect clip (set_clip_rects) for shaped clips such as a circular avatar, a rounded card or a VectorDrawable mask. See examples/clip_path.rs.
• Canvas::fill_path / Canvas::stroke_path over a new PathCmd command list (MoveTo / LineTo / QuadTo / CubicTo / Close, in surface coordinates) — renders an arbitrary vector path, a Path, a VectorDrawable or a Lottie frame. The software backend rasterises directly with tiny-skia; the GLES backend rasterises into a tiny-skia pixmap and uploads it, so both backends share the same path rasteriser and stay at visual parity.
• Canvas::read_rgba_pixels — reads any canvas into tightly packed straight-alpha RGBA8 (top-left row first), on both the GLES and software backends (the software path un-premultiplies its pixmap). Canvas::is_software lets a caller branch on the backend (e.g. honour a real path clip on software but only a bounding rect on GLES).
• measure_text( text, size ) (re-exported at the crate root) — measures one line with the default UI font and the system fallback chain, returning (width, line_height) in pixels without a live Canvas, for an embedder's measure pass that must match the renderer's metrics. Backed by a process-wide cached primary-font handle.
• Stack::push_placed — appends a child at an exact rect, bypassing alignment and intrinsic sizing, so a view tree whose geometry is computed elsewhere can be projected onto a Stack in paint order. Stack::push_placed_clipped additionally clips the child's subtree to a rect (Android's clipChildren): overflowing content is not painted.
• ExternalSource::Cpu and the External::cpu constructor — an immediate-mode CPU drawing closure invoked once per frame with the canvas and the widget's laid-out rect, working on both backends. Hosts a custom View.onDraw straight onto the ltk canvas without a GL texture round-trip, unlike the existing Texture source which only renders on GLES.
• RichText widget — wrapped paragraph text carrying a Msg per clickable link range; the layout pass emits one hit rect per link line so taps land on the link rather than the whole paragraph. The ltk side of an Android Spanned carrying URLSpan / ClickableSpan.

Fixed

• GLES clip-layer composite no longer renders path-clipped content vertically flipped: the offscreen layer was sampled at the inverted screen Y. The software backend was unaffected.
• Gesture: the horizontal pager is driven only once the swipe axis locks horizontal. Previously the pre-lock lateral drift of a vertical gesture could arm the consumer's pager without a matching release event, which could freeze the surface until an unrelated gesture reset it.
• Software/GLES parity: the software backend now snaps glyph pen positions and image destinations to integer pixels (rounding to nearest), matching the GLES backend. Previously it truncated, so text and 1:1 images could land up to half a pixel off between backends and sample ~1 px softer.

Changed

• Default theme launcher SVGs replaced with renderer-compatible versions.

0.1.0 - 2026-03-10

Added

• Initial release.