EMF+ region and pattern painting

Pinned TortoiseGit: 7338078f8ddd924b8cddee35f512f2286072136d. TortoiseIDiff/MainWindow.cpp:1255 includes Windows metafiles in its file filter; Utils/MiscUI/Picture.cpp::Load uses GDI+ decoding. This extends the bundled metafile decoder so existing Compare and image-conflict panes can open more of those files. Captured repository bytes remain authoritative; rendering creates only private display data.

Region geometry and clipping

The format contracts are Microsoft's region object, region nodes, FillRegion and SetClipRegion. Region trees carry rectangle, path, empty and infinite leaves and Boolean AND/OR/XOR/Exclude/Complement operations. RegionNodeCount describes child nodes; the root is additional. A malformed tree cannot silently become a rectangle.

Region fills resolve the record's brush ID or inline ARGB flag. Region clips combine with the existing clip in device coordinates so later world transforms do not move an already captured clip. Indexed Save/Restore and graphics containers retain that captured state. Each object is limited to 4,095 nodes, depth 64 and 262,144 path points. Each conversion reserves region work before painting, capped at 65,536 node visits and 1,048,576 path-point visits. Referenced masks avoid recursively copying child markup; mask construction is capped at 65,536 definitions and 64 MiB of body markup. Unsupported encodings continue to fail explicitly.

Hatch cells and texture brushes

Microsoft's hatch brush and HatchStyle enumeration define independent foreground/background colors and 53 styles. Their eight-pixel cells come from Wine's pinned HatchBrushes table, isolated in src/turtleGitHatch.js. They are not average-color substitutes or newly invented patterns. Foreground/background alpha and device phase remain separate from the filled geometry.

Texture brush fields, optional matrix and image and brush flags provide the texture contract. Bitmap bytes use the existing bounded native raw/compressed-image adapters. Brush matrices, world transforms, wrap/reflection and DoNotTransform are handled independently; an already gamma-corrected texture is not corrected a second time. Native CoreSVG's bitmap pattern limitations require explicit display painting with bounded raster/tile work. Clamp paints the original texture extent rather than repeating it. Repeated texture cells retain negative-index phase and independent X/Y reflection.

The initial local implementation assumed CoreSVG would supply a 2× raster and used bilinear footprint sampling to reduce it to intrinsic size. Hosted macOS 15.5 demonstrated that this was not a portable contract: hatch colors/phase and wrapped-gradient stops failed their unchanged pixel assertions. The explicit raster continuation replaces that assumption with a controlled intrinsic-size render. Hatch coverage blends premultiplied colors before unpremultiplication so a transparent colored foreground cannot contaminate background RGB. The original vector geometry still clips the brush paint; this does not provide unlimited resolution pattern rerendering on zoom.

Source and licensing

The base renderer remains MIT-licensed WmfEmfViewer at 4e0d6d6807349ebfc8f8c681009c14f9e57621ff. The hatch table is adapted from Wine brush.c at 7298a818, under LGPL-2.1-or-later. Its copyright and source revision accompany the adapted module; Licenses/Wine-LGPL-2.1.txt, NOTICE and exact patch sources accompany the packaged runtime. Configuration/MetafileRuntime.json records the full source hash. No Wine executable or library is linked or required. Reconstruction and hosted cache inputs include the added license and notices.

Validation and remaining work

The dated evidence records the universal runtime/source/license reconstruction, Debug app build, 26 distinct passing metafile Core methods, six runtime-cache checks and four native case/engine pairs. The initial Core failures, sampling diagnostic and focused rechecks remain recorded. Twenty-five methods passed after the production sampling repair; only the remaining fixture's corrected texture-center method needed another run. No full application Core suite was repeated.

The 44 new original records cover region Boolean truth tables, all six clip combine modes, float/int16 path geometry and holes, infinite/empty leaves, captured transforms/restores, all 53 hatch styles, origin/device phase, unequal alpha, texture wraps/matrices/DoNotTransform/gamma flags and malformed/resource refusals. The native receiver loads representative new images through actual two-side Compare and a real three-stage region/hatch/texture conflict, reloads them and retains original bytes, HEAD, index and working files. Both Git engines also pass the retained native color/alpha/theme/ownership checks. All four owned receivers were reaped and their PID/process-group absence checked afterward. These checks ran on the local arm64 host; universal slices are not full Intel rendering proof.

Full Windows pixel identity, physical zoom/font/antialiasing acceptance, current signed-parent execution and complete hosted integration remain separate gates. Relative/RLE region paths, negative rectangle extents, singular/ill-conditioned region fill transforms and nested-metafile textures remain explicit refusals. Classic WMF region/flood filling, uncommon raster operations, advanced pens, complex glyph/StringFormat layouts and other documented format gaps remain open. This batch does not certify every Windows metafile or the complete application.

Explicit native raster continuation — October 19, 2026

The full hosted bfa1fafe run compiled the app and extension successfully, then ran 2,089 Core methods with two skips and 86 failed assertions in three metafile methods. The failure is broader than the earlier local pattern checkpoint: checker cells lose both pure colors, eight-pixel phase comparisons drift, and a wrapped-gradient sample is blurred. Earlier ARM-only passes do not certify this hosted raster path. Dated evidence retains the failed run and subsequent scoped implementation/checks.

The compatibility family controls the SVG bitmap dimensions and named sRGB color space instead of relying on an unspecified cached NSImage representation and a guessed 2× reconstruction. Embedded painting samples follow device-pixel centers, while vector clipping/antialiasing and captured hatch alpha/origin/world state retain their existing contracts. Input and aggregate painting limits remain bounded. Original pixel assertions remain part of acceptance; no wider tolerance or successful blank/average-color substitute is introduced.

Current hosted revalidation, physical Intel/minimum macOS, arbitrary source painting and the later signed distribution candidate still require separate acceptance. This family does not certify all metafile formats or the whole port.

A new diagnostic initially compared a plain native SVG vector gradient with a literal channel-interpolation formula; the local native backend returned other channel values. That observation remains a separate plain-SVG color-interpolation acceptance gap. SVG specifies sRGB as the initial interpolation space, so this observation does not invalidate the original formula or establish native SVG conformance. The strict reconstruction regression instead embeds an independent named-sRGB pixel ramp, matching the metafile helper's actual paint contract, and compares every channel at its expected device-pixel center. The existing hatch/gradient predicates are retained. The raw helper pixels and final native raster are checked separately so another resampling stage cannot hide a painting or phase error.

The explicit-raster checkpoint passed 33 distinct current Core methods cumulatively (32 initial and the one corrected embedded-ramp case). Debug passed; four native consumer/color case/engine pairs passed cumulatively. The first bundled native attempt inherited the live desktop Shift key and intentionally selected Merge before decoding. Pinning the test-owned task-local default choice repaired that fixture without changing production routing or relaxing its image assertion. Only failed/unrun native pairs were repeated. All five receivers, including the failed attempt, were reaped and independently absent by PID/group. No full local Core suite or current signed/hosted acceptance is claimed.

The compressed-path continuation supersedes the earlier relative/RLE region-path refusal. Region tree, coordinate and mask budgets remain independent of the shared path decoding/tracing budgets.