flutter_md 0.3.1

Fast Markdown parser and canvas renderer for Flutter with cross-widget text selection, streaming parsing and syntax highlighting.

0.3.1

Rendering

• IMPROVED: Highlighted code blocks are cheaper with identical pixels: MarkdownHighlighter.highlight returns a flat list with one span per run of text painted alike. On real devices the first display is 20-31% cheaper and a streamed chunk 20-40%. Code reading the nested token spans sees flat ones.
• IMPROVED: MarkdownHighlighter keeps its latest results (up to 256 KB of code), so a block seen before is not tokenized again.
• IMPROVED: Layout is cheaper with identical output: in the headless benchmark, up to 22% off a first frame of a large mixed document and up to 14% on lists. A table that fits no longer measures the longest word of every cell, list items with the same marker share one laid-out painter, and unstyled spans skip re-encoding the parent style.
• IMPROVED: Streaming is 5–8× cheaper per chunk on real devices. An update keeps the painters of the unchanged blocks at the start of the document, and records only what follows them. Applies to a theme without builder, imageResolver, blockFilter or spanFilter.
• IMPROVED: Relayout at a new width is 16–24× cheaper: lists and tables keep their text painters across layouts instead of rebuilding them.
• IMPROVED: Rebuilding a parent no longer lays out a document whose text and theme values did not change, even when the Markdown or theme is a new object.
• FIXED: MarkdownPainter.update released replaced block painters and pictures only on garbage collection; it now disposes them. A painter from a host builder is still left to the host.
• CHANGED: paragraphFromMarkdownSpans leaves style null on an unstyled child span, which inherits the parent TextSpan's style. The result looks the same; code reading child.style directly sees null.

Parser

• ADDED: Markdown.fromStringAsync and MarkdownDecoder.convertAsync parse a long document in slices of 4 ms by default, pausing until the end of the frame when one is on the way. The result equals that of the sync parse. For 5 MB, the longest gap between frames falls from 129 to 19 ms on an iPad Pro and from 258 to 34 ms on a Galaxy S22 Ultra, for 2-3 times the total time. A single huge block is still parsed in one go.
• FIXED: A paragraph with more than 65535 links or images hung the parser in an endless loop. Links are now matched by a cursor, with no size limit.
• FIXED: Hostile input no longer freezes the UI. Parsing is linear for unclosed emphasis markers, backticks after an escaped backslash, tables that fail validation, label openers, spaces inside a heading (32 KB took more than 15 seconds), deeply nested > (8 KB with a fence took more than 20 seconds) and unclosed ^{ / _{ in inline math.
• CHANGED: A fenced code block is parsed as nested blocks down to 32 quote levels. Below that the quote body is inline text, so input cannot overflow the stack however deep it nests.

Selection

• FIXED: "Looking up a deactivated widget's ancestor is unsafe" from MarkdownSelectionScope's controller listener. Since the desktop-menu fix in 0.3.0 it reads Theme.of(context) on every clear, and a host that clears the selection or re-registers documents from a widget's dispose (a chat body leaving a virtualized list) notifies while the scope above that body is deactivated. The scope now reads the platform in didChangeDependencies.

Benchmarks

• ADDED: docs/benchmarks.md: results per device with hardware, versions and method, for an iPad Pro, a Galaxy S22 Ultra and a MacBook Pro. The on-device suite is benchmark_compare/tool/device_bench.sh.

0.3.0

Upgrading from 0.2.x? See the migration guide. Ordinary MarkdownWidget / MarkdownSelectionScope users need no code changes; hosts that implement the render / selection extension points do. Coming from pub.dev 0.0.8? 0.1.0 and 0.2.0 were never published there — read the 0.0.x → 0.2.x guide first, then this one.

Breaking vs 0.2.0

Source-breaking only for hosts that implement the render / selection extension points, reach into a default block painter's fields, or read the quote / alert model directly. Ordinary MarkdownWidget / MarkdownSelectionScope users are unaffected.

• REMOVED: BlockPainter$Quote.painter and BlockPainter$Alert.bodyPainter. Both painters now stack nested children, so a single body TextPainter no longer exists. Read renderedText / fragments (from MultiPainterSelectable) instead.
• CHANGED: BlockPainter$Quote and BlockPainter$Alert mix in MultiPainterSelectable instead of SelectableTextBlock. Subclasses that overrode selectionPainter / selectionOrigin must move to fragments. Both constructors gained an optional children: (the nested block painters) and blocks: (the matching child models, which keep selection offsets in sync when a child painter exposes no selectable text); a custom builder that rebuilds them must pass both for bodies with nested blocks. BlockPainter$Quote.inheritFrom gives a nested child the theme the default quote uses.
• CHANGED: A quote / alert whose body contains a fenced block now has empty spans; its content is in the new MD$Quote.blocks / MD$Alert.blocks. Code that builds BlockPainter$Quote/Alert(spans: …) in a custom MarkdownThemeData.builder, or otherwise walks spans, must handle blocks. Plain quotes / alerts keep the leaf shape (spans, empty blocks).
• CHANGED: SelectableBlockPainter gained positionAndAffinityForLocal, caretRectFor, hitsRenderedTextAt and selectionHighlightAboveCachedContent. Custom painters built on the SelectableTextBlock / MultiPainterSelectable mixins inherit working implementations; painters that implements SelectableBlockPainter directly must add all four.
• CHANGED: MarkdownSelectionSurface gained textDirection, hitForGlobal, hitsSelectableGlyphs, isLinkAtGlobal, caretRectFor, localBoxesForRange, hasSelectionHandleLeaders and clearSelectionHandleLayersIfLinked. Custom surfaces must implement them.
• CHANGED: MarkdownSelectionController.startAtGlobal / selectWordAtGlobal / selectBlockAtGlobal ignore points outside every mounted surface (new requireContainment, default true) instead of clamping onto the nearest markdown. Pass requireContainment: false for the old clamping.
• CHANGED: ParagraphGestureHandler.hitTestInlineSpanWithPointerEvent returns null for a point outside the painter's box. A tap in the empty space before right-to-left text used to snap onto the line's last glyph and open a link ending it.
• CHANGED: MarkdownThemeData.copyWith returns MarkdownThemeData instead of ThemeExtension<MarkdownThemeData> (callers gain, overriders must narrow).
• CHANGED: MarkdownRenderObject.updateSelection takes an optional markdown:. @meta.internal, but MarkdownWidget subclasses that call it must now invoke it before update (see the registry fix below).
• CHANGED: With an imageResolver set, paragraphFromMarkdownSpans may emit MarkdownImageSpan (a PlaceholderSpan) children, so TextPainter.plainText holds U+FFFC where the model has alt text. SelectableTextBlock.renderedText and SelectableFragment.length now come from the model text. Lay out / paint custom painters with layoutMarkdownText / paintMarkdownText.
• CHANGED: Code spans render in Menlo (iOS / macOS) / Consolas (Windows) instead of the unresolvable 'monospace', with a fallback chain on every platform (see Monospace font resolution). Expect golden diffs there.

Inline images & link icons

• ADDED: ![alt](src) images can render as pictures, and links can carry an icon in front of their label (a site favicon). Opt-in through MarkdownThemeData.imageResolver — without one, images keep rendering as their alt text, so nothing is fetched behind the host's back (tracking pixels).
• ADDED: MarkdownImage, the picture interface: it reports the size of its slot in the line (layout), paints itself into it (paint) and calls notifyListeners when it loads, fails or animates. Implement it to control sources, caching and appearance; MarkdownImageResolver maps a MarkdownImageRequest (kind, url, text — the alt text or link label — and title) to one; MarkdownImageConstraints carries the line's width and text style.
• ADDED: MarkdownProviderImage (any Flutter ImageProvider — network, file, asset, memory or a disk-cached third-party provider; .icon for a text-sized link icon) and the ready-made MarkdownProviderImageResolver (http(s) and data: images, /favicon.ico link icons, baseUri for relative sources, swappable imageProvider / faviconUri).
• ADDED: MarkdownImageSpan, layoutMarkdownText and paintMarkdownText for custom block painters whose text comes from paragraphFromMarkdownSpans; a painter that keeps calling plain TextPainter.layout still lays out (a text-sized empty slot per picture).
• Selection is unchanged: a picture counts as its alt text (a link icon as nothing), so offsets, highlight and copied text match markdownBlockRenderedText whether or not pictures are shown; a range touching the alt text highlights the whole picture, and a double tap on it selects it.
• Pictures are owned by the rendered document: a request seen before reuses the loaded image (streaming rebuilds and repeated images load once), and images that leave the document are disposed. A size change re-lays out the widget; any other change only repaints it.
• A resolver (or imageProvider callback) that throws is reported through FlutterError.reportError and the image falls back to its alt text; the rest of the document still renders. A null result is remembered for the request while it stays in the document. In-page anchors (#section) never get a link icon, and data: image MIME types match case-insensitively.
• Keep the resolver stable (a const resolver's .call, a field or a top-level function): a different resolver drops and reloads every picture.
• Known limitations: a failed load is not retried while its URL stays in the document; an animated image re-records the document's cached picture on every frame; a link icon that fails to load collapses, shifting its label once. Keyboard character steps walk an image's alt text one code unit at a time, so an endpoint can sit inside it — the whole picture highlights while the copy holds part of the alt text.

Syntax highlighting

• FIXED: Grammar rules marked greedy (Prism's semantics) now match across tokens claimed by earlier rules. A comment marker inside a string ("a # b" in Python / Bash, 'http://…' in JS) no longer turns the rest of the line into a comment, and Ruby / Elixir #{…} interpolation is highlighted inside strings. Highlighting stays lossless.
• FIXED: Tokenizing is linear in the number of tokens: each rule builds its result in one pass instead of splicing per match. A 10,000-line C block went from ~7 s to ~0.3 s; typical blocks are a little faster too. A greedy rule whose matches keep starting inside other tokens falls back to plain matching after a bounded number of tries.
• FIXED: HighlightThemes.githubDark / githubLight color diffs: inserted and deleted lines get GitHub's green / red, hunk headers (coord) the function color. Previously a diff rendered uncolored.

Parser

• FIXED: List items at uneven indents are kept: in - a / - b / - c, b was dropped (the shallower c replaced a's children instead of joining them).

Quote / alert nested fenced code

• FIXED: Fenced code (```lang / ~~~) inside a blockquote or GitHub alert is re-parsed as nested MD$Code in MD$Quote.blocks / MD$Alert.blocks, instead of being consumed as inline monospace by backtick pairing (`` + monospace + ``). The fenced code keeps its indentation, fences inside nested quotes (> > ```…) are nested code too, and a fence may follow the > after up to three spaces or a tab (lines inside the code keep their indentation verbatim). Blank > lines around an alert body add no extra gap.
• ADDED: Optional blocks on MD$Quote / MD$Alert (empty for leaf inline bodies). Render, markdownBlockRenderedText and Markdown.text walk nested children when present (Markdown.text yields the children's span text, not raw markup). Nested children route through MarkdownThemeData.builder like top-level blocks, so a host that replaces the code painter (a fence with a copy button, say) gets it inside > … too. Prose nested inside a quote (paragraphs / lists / headings beside a fence) uses quoteStyle; code / table chrome keeps the document theme. Links open on tap in every nested child kind, in either text direction.
• FIXED: A quote / alert whose nested table overflows still paints, and a host-supplied non-selectable nested painter keeps selection offsets in sync with markdownBlockRenderedText.

Glyph-tight hit testing

• CHANGED: Hover I-beam and link hit-testing use rendered line/glyph boxes, not the full max-width layout of a paragraph. Empty horizontal gutter beside a short line (quote and alert bodies included) is no longer I-beam / click-to-open. Glyph boxes are cached per TextPainter layout, so hovering stays cheap over long fenced code blocks.
• CHANGED: Gesture starts (hitsSelectableContent) stay surface- bounds. A press inside the document or bubble arms text selection. Drag-extend may still clamp outside glyphs.
• CHANGED: Mouse single-click that misses selectable content while a non-collapsed range is active clears the selection, instead of leaving the old range.
• ADDED: SelectableBlockPainter.hitsRenderedTextAt, MarkdownSelectionSurface.hitsSelectableGlyphs, and MarkdownSelectionController.hitsSelectableGlyphs.

Selection host gates

• ADDED: MarkdownSelectionScope.canStartSelectionAt — optional host gate so enclosing UIs can refuse selection starts on chrome (links, code headers) without the scope claiming the pointer. A refusal also un-arms the drag (the recognizers still join the arena while a range is live, so a chrome tap can dismiss it), so a long press / drag on refused chrome neither extends the active selection nor shows the toolbar.
• ADDED: MarkdownSelectionScope.enableTouchGestures — when false, touch / stylus / trackpad selection recognizers stay off; mouse multi-click, handles, toolbar, and keyboard remain. Focus loss also does not clear the range (host viewport may steal focus).
• ADDED: MarkdownSelectionScope.enableTouchConsecutiveTaps — when false (with enableTouchGestures true), touch long-press → word → drag-extend still arms, but touch multi-tap / horizontal-drag selection does not. Chat hosts use this so taps stay with the viewport while continuous text entry works. Focus loss also does not clear the range in that mode.
• ADDED: MarkdownSelectionScope.ownsSelectionChrome — optional host gate so only the scope that owns the selection’s document paints handles/toolbar when several scopes share one controller (chat per-body mounts). A non-owning or disabled sibling clears only handle leaders that reference its own LayerLinks, and removes its own adaptive toolbar when ownership moves away; toolbarWanted is left for the owning scope to restore on settle.
• ADDED: MarkdownSelectionSurface.hasSelectionHandleLeaders, clearSelectionHandleLayersIfLinked, and MarkdownSelectionScopeState.selectionHandleLeadersAttached for observing coherent handle-leader attachment across multi-scope hosts.
• CHANGED: Flipping enabled from false → true with an existing non-collapsed range restores handles; when toolbarWanted is set, restores the toolbar. While disabled, the scope stays inert for chrome (no toolbar / handles) but keeps toolbarWanted for that restore path. Disabling the scope mid-drag aborts the drag.

Dynamic cursor resolution & span bounding boxes

• ADDED: MarkdownThemeData.cursorResolver and MarkdownWidget.cursorResolver (MarkdownCursorResolver) — unopinionated hook to dynamically resolve hover mouse cursors per local offset, block index, and block model, falling back to default link/text/defer cursors when returning null. The hover cursor survives rebuilds that pass a new resolver closure and re-resolves when the theme or resolver changes.
• ADDED: MarkdownSelectionSurface.localBoxesForRange (backed by the internal MarkdownPainter.localBoxesForRange) — fast query returning content-local bounding boxes for an arbitrary character range within a block, directly from cached block painters without re-layout.

Registry / multi-body selection

• FIXED: removeDocument defers while a surface for that id is mounted and flushes on detachSurface; a later putDocument cancels the pending remove. Parent State.dispose can run before child detach — eager remove left hittable surfaces with no registry entry (rangeFor / ordering broken).
• FIXED: rangeFor and endpoint ordering ignore unregistered document ids instead of treating them as index -1 (which painted every body from the start of the registry through the other endpoint).
• CHANGED: MarkdownRenderObject heals with putDocument on attach / when the controller is wired while already attached, so a mounted selectable surface is never missing from the registry. Prefer explicit app registration for unmounted docs and unique reading-order order values.
• FIXED: Recycling a MarkdownWidget element onto a different documentId (a virtualized chat list reusing a slot) overwrote the outgoing document's registry model with the incoming body. MarkdownWidget now rewires the selection registry before pushing the new model, and MarkdownRenderObject.updateSelection takes the incoming markdown: so the heal lands on the right id.
• FIXED: putDocument without an explicit order appended at _docs.length which sorted ahead of sparse explicit orders (chat hosts key order on the message id), so a healed body jumped to the front of the conversation and reversed extracted text. It now sorts after every registered document.
• FIXED: Documents sharing an order could swap places on any re-sort (List.sort is not stable), silently reversing extracted text. Ties now break on registration sequence.
• FIXED: MarkdownSelectionScope.onSelectionChanged fired synchronously from inside build / layout — a streaming putDocument reconciling the range away (from MarkdownWidget.updateRenderObject) or a deferred removeDocument flushing from RenderObject.detach threw "setState() called during build" in any host that rebuilds from the callback. Delivery is now coalesced to the end of the frame in those phases.
• FIXED: selectAll skips documents with no blocks, so an empty streaming message no longer turns it into a no-op.
• FIXED: Reconciling a range onto a document with a duplicated block keeps the copy nearest the old position.
• FIXED: A drag update that lands on the current position no longer notifies listeners.

Selection chrome (SelectionArea parity)

• ADDED: Read-only selection chrome on the controller / MarkdownSelectionScope path brought up to Flutter SelectableRegion / SelectionArea quality without remounting SelectionArea:
  • Content-gated touch TapAndHorizontalDragGestureRecognizer + long-press (consecutive taps, no DoubleTapGestureRecognizer arena delay); mouse TapAndPanGestureRecognizer.
  • Gesture starts require a hit on mounted selectable markdown (chrome / empty space do not nearest-neighbor clamp); clamp remains for extend across gaps.
  • Soft-wrap affinity on handles; directed base/extent edges with reverse handle types; coincident-caret separation; handle proxies when an endpoint surface unmounts (virtualization), on the correct end for reversed selections too.
  • Native SelectionOverlay handles + magnifier on touch; LeaderLayer follow across scroll / multi-widget hosts.
  • Keyboard Copy / Select-all / Shift-extend / Esc; adaptive Copy / Select-all toolbar with live re-anchoring.
  • Word / block granular multi-tap and long-press; link hand cursor / I-beam on selectable content.
• ADDED: MarkdownSelectionController.isSelectionReversed (base after extent in reading order), selectionEndpointGlobalRect({base}) (global caret rect of a mounted endpoint, null when unmounted, no proxying), selectionEndpointOverlaps(rect, {base}) and anySelectionEndpointOverlaps(rect) (whether a mounted endpoint caret intersects a global rect), and toolbarWanted (the toolbar-restore intent; reset when the registry drops or collapses the range).
• CHANGED: Toolbar hides while expanding (body or handle drag) and may re-show on drag end; anchors recompute on selection change, host/ancestor scroll, and mounted-surface layout change. Scroll-driven restores are skipped while a drag is active.
• CHANGED: Toolbar placement — both endpoints in clip use stock above-preferring anchors; bottom-only endpoint prefers below that caret; neither endpoint in clip (tall mid-viewport) top-pins so the below-fallback cannot sink to the host bottom; empty intersection hides the overlay while toolbarWanted restores on scroll-back / remount.
• CHANGED: Desktop selection toolbar parity with stock Flutter:
  • On desktop (macOS, Linux, Windows), mouse drags, double/triple clicks, keyboard shortcuts (Cmd/Ctrl+A), and programmatic selection updates do not pop up the toolbar.
  • Right-click on desktop shows the context toolbar at the click coordinates without mutating the active selection (no select-word / caret collapse).
  • Desktop context menu preserves its right-click anchor when triggering actions such as "Select all", rather than jumping to selection endpoints.
  • Desktop context menu dismisses immediately upon scroll, but survives streamed updates, sibling updates and resizes, with or without a selection.
  • On mobile (Android, iOS), touch gestures and programmatic selection (selectAll, selection = ...) continue to present the adaptive toolbar and handles with action items.
• FIXED: Selection highlight stays outside the glyph Picture cache — under glyphs by default (sharp text), with a second pass above opaque chrome (selectionHighlightAboveCachedContent) for code fences, table zebra rows, and inline monospace / highlight backgrounds.
• FIXED: Focus loss does not clear selection while a pointer drag is active (list rebuilds during autoscroll); geometry walks defer off performLayout.
• FIXED: Esc with no selection is no longer swallowed by the scope, so it reaches ancestors (closing a dialog, say).

Edge autoscroll while selecting

• ADDED: Edge-zone autoscroll while dragging (body / handle / long-press) near the padded viewport — host-union hard-stop, direction arming gate, past-viewport max velocity while the union still allows that direction (MarkdownSelectionScope.autoscroll, MarkdownSelectionAutoscrollConfig with copyWith / ==, default edgeZone: 48). Edge bands are capped at half the viewport; speed is time-based, not tied to the pointer event rate; a vertical edge drag only drives a vertical Scrollable; pointer cancel and long-press cancel stop it. The scroll surface is resolved once per drag.
• ADDED: MarkdownAutoscrollTarget — the scroll surface autoscroll drives, behind three members (viewport, canScroll, applyScrollDelta). Deltas are screen-space content movement (positive moves content up), never scroll offsets, so reverse axes and inverted anchors are the adapter's problem.
• ADDED: MarkdownScrollableAutoscrollTarget — the built-in sliver adapter (ScrollableState / ScrollPosition), used when no resolver is configured. Handles AxisDirection.up / .left sign flipping.
• ADDED: MarkdownSelectionAutoscrollConfig.targetResolver (MarkdownAutoscrollTargetResolver + MarkdownAutoscrollRequest) so a host with its own scroll implementation — an anchored chat viewport, a RenderBox that positions children itself, a transform canvas — can be driven without a Scrollable anywhere in the tree. Plus MarkdownCallbackAutoscrollTarget and MarkdownAutoscrollViewport (global bounds + band inset) for closure hosts.
• ADDED: MarkdownSelectionAutoscrollConfig.useHostUnionGate (default true). Turn it off when the markdown bodies are the scrolling content and the host builds only what is visible: such a host's mounted union is barely larger than the viewport, so the gate would veto a drag that should keep paging through history. The target's canScroll and the delta it reports applying are then the only stops.

Layout

• FIXED: MarkdownWidget reports its intrinsic height and max intrinsic width, so IntrinsicHeight (and similar) no longer collapses it to 0.
• FIXED: A fenced code block too narrow for its padding is inert for selection, so selectAll at tiny widths no longer crashes, and no longer throws TextPainter.paint called when text geometry was not yet calculated while painting (at widget widths of a few dozen pixels, less inside a quote or alert).

Right-to-left layout

• FIXED: With MarkdownThemeData.textDirection set to TextDirection.rtl, blocks were still laid out left-to-right: paragraphs and headings sat against the left edge, list bullets, quote bars and the alert accent bar were on the left, and table columns ran left to right. Blocks now mirror: text aligns to the right edge, bullets and bars sit on the right, and the first table column is on the right (unaligned data cells start on the right; explicit :-- / --: alignment stays physical). Link taps, hit testing and text selection follow the mirrored positions, under tight and min-width constraints too. Left-to-right layout is unchanged.
• FIXED: Selection handles on right-to-left text sit at the logical start (right edge) and end (left edge) of the selection. Each handle follows the textDirection of the document it sits on, not the ambient Directionality: the two can differ, and one selection can span documents of both directions. Proxy handles for a scrolled-off edge land on the reading start / end of the visible selection in either direction.
• FIXED: A table too wide to fit overflows past its end edge in either direction, so the columns read first stay in view (to the left of the widget for right-to-left text).
• FIXED: Link taps inside quotes account for the quote's indent.
• CHANGED: Under tight constraints (for example a fixed-width chat bubble), right-to-left content aligns to the full width, like Text. Under loose constraints the widget still sizes to its content.
• CHANGED: Fenced code blocks always render left-to-right, even in right-to-left documents.
• ADDED: ParagraphGestureHandler.hitTestInlineSpanWithPointerEvent takes an optional origin, for painters whose text is not painted at the block origin.
• FIXED: A dry layout at other constraints, made after the real layout, left hit testing, highlights and link taps at the measured positions while the glyphs stayed put. The real layout is now restored after measuring.

Monospace font resolution

• FIXED: Inline `code` and fenced blocks pick a monospace family the host platform can actually resolve. Flutter hands the family straight to the platform font manager, and CoreText (iOS / macOS) and DirectWrite (Windows) do not know the CSS generic 'monospace' — code silently rendered in the proportional body face there. Those two now get Menlo / Consolas. Android, Fuchsia, Linux and web keep 'monospace', so the primary face there is unchanged. Note that on web it is unchanged but still wrong: CanvasKit / skwasm reach no system fonts, so no family name resolves there and code has always rendered in the proportional default. Bundling a monospace asset and pointing monospaceFontFamily at it is the only fix, and that is a host decision.
• CHANGED: code spans now carry a fontFamilyFallback on every platform: the monospace chain followed by whatever textStyle already carried. A monospace face covers Latin and little else, so the body face's chain is appended rather than replaced — a host's CJK / emoji coverage keeps working inside `code` and fenced blocks.
• ADDED: MarkdownThemeData.monospaceFontFamily / monospaceFontFamilyFallback to pin a bundled face. Both default to the platform-resolved chain above and are resolved once, in the constructor. One knob covers both inline `code` and fenced blocks — there was previously no supported way to change the fenced-block face at all: BlockPainter$Code built its style in a static method reading a global, so even overriding textStyleFor moved inline code only. An empty fallback list means "no monospace fallbacks", not "unset" — textStyle's own chain still applies.
• CHANGED: MarkdownThemeData.mergeTheme resolves the default face from ThemeData.platform rather than the global defaultTargetPlatform, so an app that adapts its Material theme to another platform gets that platform's face. ThemeData.platform defaults to defaultTargetPlatform, so this only moves for an app that deliberately overrode it.

0.2.0

Upgrading from 0.0.x? See the migration guide. 0.2.x is almost entirely backward compatible — the only required code change is a new alert branch for direct MD$Block.map / switch callers.

• ADDED: Opt-in, dependency-free syntax highlighting for fenced code blocks (65+ languages, GitHub light/dark themes). Assign a SyntaxHighlighter to the new MarkdownThemeData.highlighter field; the default (unset) renders code as plain monospace, so existing usage is unchanged. New public API on package:flutter_md/highlight.dart: SyntaxHighlighter, MarkdownHighlighter, CodeHighlightTheme, Grammar, GrammarToken, compileHighlightPattern (SyntaxHighlighter / CodeHighlightTheme are also re-exported from the main entrypoint). Each language is its own library (package:flutter_md/highlight/<lang>.dart, e.g. HighlightDart.grammar) with no central registry, so importing one never references the others and unused grammars tree-shake away — a Dart-only app adds ~0 beyond the engine; all 65 add ~62 KB gzipped. HighlightThemes.githubDark / githubLight (highlight/themes.dart) provide ready themes; allHighlightLanguages (highlight/all.dart) is a convenience registry of every grammar for demos/tooling (it references all languages, so unused ones can no longer tree-shake away). The highlighter only partitions text — never edits it — so selection and copy stay aligned. Grammars are generated by tool/highlight_codegen (adapted from Prism, MIT).
• ADDED: Cross-block and cross-widget text selection. A MarkdownSelectionController anchors the selection on the immutable model, so it spans multiple blocks and multiple MarkdownWidgets and survives list disposal (e.g. chat scrolling). New public API: MarkdownSelectionController, MarkdownSelectionScope, MarkdownSelectionGroup, MarkdownPosition, MarkdownSelection, MarkdownDocumentRef, MarkdownSelectedContent (+ document/block), MarkdownSelectionFormatter / MarkdownPlainTextFormatter / MarkdownMarkupFormatter, MarkdownReconciliationPolicy, MarkdownSelectionSurface, markdownBlockRenderedText, and SelectableBlockPainter / SelectableTextBlock.
• ADDED: StreamingMarkdownParser, an incremental parser for streaming sources such as LLM token output. It freezes completed blocks (a block ends at a blank line, outside any open code fence) so only the still-growing tail is re-parsed as tokens arrive — turning the O(N²) cost of re-parsing the whole buffer on every token into roughly O(tail) (3–14× faster on a full message stream in benchmark/streaming_benchmark.dart). parser.add(chunk) returns the growing Markdown, always identical block-for-block to Markdown.fromString(everythingSoFar), and a Stream<String>.toMarkdown() extension wires it into a stream transform. Pass a configured MarkdownDecoder (e.g. inlineMath: true) to match Markdown.fromString. The batch MarkdownDecoder hot path is byte-for-byte unchanged.
• ADDED: MarkdownMarkupFormatter, a built-in "Copy as Markdown" formatter. Pass it to getText() (or set controller.formatter) to reconstruct Markdown structure on copy — heading #s, nested list markers with task checkboxes, blockquote/alert > prefixes, fenced code and pipe tables — for blocks the selection covers in full; partially-selected boundary blocks fall back to the plain sliced text so nothing outside the selection is emitted. The default copy behaviour is unchanged (MarkdownPlainTextFormatter).
• ADDED: MarkdownWidget gains optional documentId and controller parameters (resolved from the ambient scope). Backward compatible: a widget with no documentId is inert.
• ADDED: Lists and tables are now interactively selectable. A new MultiPainterSelectable mixin (+ SelectableFragment) maps pointer positions and highlight boxes across the many TextPainters of a list's items or a table's cells, so a drag can start or end inside a list item or table cell and the copied text keeps the \n / \t separators of markdownBlockRenderedText.
• ADDED: Keyboard shortcuts and a context toolbar on MarkdownSelectionScope, mirroring SelectableRegion/SelectableText. When focused: Ctrl/Cmd+C copies, Ctrl/Cmd+A selects all, Shift+arrows extend by character / word / line / document (and vertically by geometry), Esc clears. Right-click (desktop) / long-press (mobile) shows an adaptive Copy / Select-all toolbar. The scope is now a StatefulWidget with a public MarkdownSelectionScopeState (copySelection / selectAll / clearSelection / showToolbar / hideToolbar / contextMenuButtonItems / contextMenuAnchors). New customization params: focusNode, enabled, selectionColor, contextMenuBuilder, magnifierConfiguration, selectionControls, onSelectionChanged. New controller ops: selectionColor, globalSelectionRects, moveSelectionEdgeToGlobal, and the extendSelectionBy* family; MarkdownPosition.copyWith.
• ADDED: Native selection handles and a magnifier on touch platforms, driven by Flutter's SelectionOverlay. Selection endpoints push LeaderLayers from the render objects so the handles follow the content as it scrolls (and across multiple MarkdownWidgets); dragging a handle adjusts the selection and shows the platform magnifier. Handles/magnifier respect the platform (selectionControls, magnifierConfiguration) and are absent on desktop, matching SelectableText. New surface geometry: localSelectionRects, setSelectionHandleLayers, repaintSelection, and MarkdownSelectionController.selectionHandleEndpoints / MarkdownHandleEndpoints.
• ADDED: Word- and block-granular selection gestures. Double-click/tap selects the word under the pointer, triple-click/tap selects the whole block, a single click collapses (clears) the selection, and Shift-click extends it. Dragging after a double/triple click keeps word/block granularity; a touch long-press grabs the whole word (then extends by word), and a touch double-tap selects the word and pops the toolbar. Word boundaries use the platform word segmentation (TextPainter.getWordBoundary), so double-click keeps intra-word punctuation like apostrophes (can't). New controller ops: selectWordAtGlobal, selectBlockAtGlobal, wordSelectionAt, blockSelectionAt, extendSelectionGranular, and wordRangeIn; new surface geometry MarkdownSelectionSurface.wordBoundaryForGlobal.
• ADDED: Mouse cursor feedback — a MarkdownWidget shows the click (hand) cursor over actionable links, the text (I-beam) cursor while it participates in a selection controller, and otherwise the default cursor.
• CHANGED: MarkdownWidget's render object now draws the selection highlight outside the cached content Picture and becomes a repaint boundary when selectable, so selection/drag repaints do not rebuild the glyph cache. The highlight color is now customizable via the controller / scope. The highlight is painted on top of (rather than beneath) the glyphs, so a translucent selection stays visible over opaque backgrounds — code fences, inline code, and ==marked== spans.
• EXAMPLE: Reworked the demo tabs — a longer, richer chat (tables, code, nested/task lists, alerts, math, token-by-token streaming with a typing indicator, Select-all/Clear) and a Selection tab that spans every block type.

0.1.0

• ADDED: GitHub-style alert blocks (> [!NOTE], > [!TIP], > [!IMPORTANT], > [!WARNING], > [!CAUTION]) via the new MD$Alert block and MD$AlertType.
• ADDED: GitHub task-list items (- [ ] / - [x]) via MD$ListItem.checked and MD$ListItem.isTask, rendered with a checkbox.
• ADDED: Table column alignment (:---, :--:, ---:) captured on MD$Table.alignments and applied when rendering.
• ADDED: linkStyle on MarkdownThemeData to customize link text styling (thanks @inamhusain, #22).
• ADDED: Per-type alert accent colors via MarkdownThemeData.alertColors and alertColorFor.
• ADDED: Opt-in $...$ inline LaTeX math conversion to Unicode, disabled by default. Enable with MarkdownDecoder(inlineMath: true) or Markdown.fromString(text, inlineMath: true). Supports LaTeX commands (\alpha, \rightarrow, ...), superscripts/subscripts (x^2, H_2O, x^{10}), is code-span and code-block safe, and preserves currency ($5). The command table is configurable via mathReplacements (extend the exported kMarkdownMathCommands). Originally proposed in #21 by @ibragimov05.
• FIXED: \$ is now a recognized backslash escape, producing a literal dollar sign (and opting a $...$ run out of math conversion).
• CHANGED: Thematic breaks now support *** and ___ (and spaced variants like - - -), and no longer greedily consume text after ---.
• CHANGED: ~~~ fenced code blocks are now recognized in addition to ```.
• FIXED: Emphasis no longer leaks to the end of the line for stray or unterminated markers (e.g. 5 * 6 = 30, **bold never closed).
• FIXED: Intraword underscores are no longer treated as emphasis (e.g. snake_case, object_id are preserved).
• FIXED: ATX headings require a space after #; #hashtag and 7+ # are no longer headings, and trailing # sequences are stripped.
• FIXED: Emphasis surrounding a link/image is now merged onto the link span.
• FIXED: Link/image targets support <url> and single-quoted titles.
• FIXED: MarkdownThemeData.copyWith no longer drops builder and onLinkTap.
• BREAKING: MD$Block.map/maybeMap gained an alert branch for the new MD$Alert block type.
• PERFORMANCE: Rewrote the parser hot path — a single-span fast path for plain text, first-code-unit guards that keep regexes off paragraph lines, hand-rolled list-line and link-target parsing (removing per-line / per-link RegExp allocation), lazy link-extraction gated on [, and a range-copy escape rebuild (no more per-character hash-set lookups). Together with math now being opt-in, the default parse path is roughly 45% faster across representative workloads (links −68%, lists −61%, escapes −68%). Output is byte-identical, guarded by a golden snapshot test.
• TESTS: Added a golden characterization snapshot, a corner-case regression suite, span-offset invariants, and unit tests for the node model, theme, and widget; wired every test file into test/unit_test.dart so CI runs the full suite (370+ tests, previously only a fraction ran). parser.dart, nodes.dart, markdown.dart, theme.dart, and widget.dart are now at ~100% line coverage.
• ADDED: benchmark/parser_benchmark.dart (a multi-scenario benchmark_harness suite) and benchmark/compare.dart (a low-noise before/after comparison tool).
• DOCS: Documented alerts, task lists, table alignment, thematic-break variants, and opt-in inline math in the README.

0.0.8

• CHANGED: New table render
• FIXED: Invalidate and relayout render object after system fonts changed.

0.0.7

• FIXED: Preserved indentation on line breaks within list items [#4].
• FIXED: Inline code no longer processes inner Markdown syntax [#10].
• CHANGED: Improved theme support.
• ADDED: Dark mode support in the example app.

0.0.6

• FIXED: Fixed escaping of special characters. [#6]

0.0.5

• FIXED: Fixed parsing url such as [text](https://domain.com/path(with)brackets).

0.0.4

• CHANGED: Improved link tap handling.

0.0.3

• FIXED: Links inside lists now work correctly.

0.0.2

• ADDED: All field in MarkdownThemeData() are now optional.
• ADDED: MarkdownThemeData{}.headingStyleFor method to customize heading styles.
• FIXED: Remove clipping for canvas. Fixes one line text trim at browsers.
• FIXED: Correctly apply styles to text in blocks.

0.0.1

• ADDED: Initial release with basic functionality.