Classic region and flood painting

Pinned TortoiseGit 7338078f8ddd924b8cddee35f512f2286072136d delegates WMF/EMF image decoding to Windows GDI+. TurtleGit's separate native display decoder must retain visible region and flood operations without rewriting repository bytes. This partial family is implemented and source-reviewed; dated evidence records its grouped checkpoint and retained limits.

Record and paint contract

FrameRgn uses a specified brush and distinct logical widths for vertical and horizontal border strokes. A region can contain adjacent bands, holes and disconnected pieces. Framing its rectangles separately introduces internal borders that do not belong to the region. The native adaptation must resolve the union first, construct its inner border, then apply the drawing transform. The native geometry policy extends normalized union-boundary strips by the distinct X/Y widths and intersects them with the original region, including concave and hole corners. It is a rectangular-erosion adaptation, not a Windows corner-pixel certification. Signed widths use absolute extents; both zero paint nothing, while one zero keeps the other direction's border. A scalar centered pen around each rectangle does not retain this behavior.

Fill and Frame use explicit brush arguments; Paint uses the selected brush. Temporary explicit-brush operations must leave the selected brush available to following records and Save/Restore. Invert uses destination inversion rather than the selected pen or fill color. Coverage must remain subject to the active clip and existing raster composition; hatch and bitmap brush holes must retain their paint policy.

The WMF region object is a scan-band object stored in the metafile object table. Its ignored linkage and object-count fields are not application handles. Record readers must retain scan extents/counts, horizontal intervals, object allocation/deletion and reuse, and reject malformed data before publishing paint. EMF embeds its own RGNDATA payload in drawing records; the outer record bounds are not a substitute for that region's geometry. The bounded WMF reader accepts the object byte extent and the additional-function-WORD convention used by Wine's recorder for RegionSize, including its 16-bit representation; arbitrary inconsistent sizes are not treated as ignored metadata.

SelectClipRgn uses a copied region in device units. WMF region painting therefore applies the current logical mapping, while selected-region clipping captures the initial metafile-to-canvas mapping. Later transforms and deleting the source object must not move or discard that captured clip. The adaptation follows the zero-argument null-region convention also implemented by Wine metafile playback; the nonzero object-index path retains normal type/lifetime checks. Subsequent WMF Intersect/ExcludeClipRect operations combine immutable device rectangle coverage, including empty regions, and Save/Restore retains the captured state. Direct normalized path children avoid CoreSVG's grouped clipPath limitation.

Destination-dependent flood filling

ExtFloodFill uses the current brush. Border mode expands from a logical seed until it reaches the supplied boundary color; surface mode follows adjacent pixels of the supplied surface color. A seed outside the effective clip, on a border in border mode, or on a different surface color in surface mode does not paint. Such a valid no-op differs from malformed record framing or an unknown mode.

The EMF record stores a logical PointL seed, ColorRef and fill-mode enum. The corresponding WMF records have their own field widths/order. Their readers must not guess a fill from a vector bounding box: the operation depends on the actual destination colors and connected visible domain after preceding paint.

The helper uses the existing guarded native SVG raster boundary and cumulative work budgets. Native color matching and seed/device-grid policy are macOS adaptations; they do not establish Windows-exact antialiasing, display palette or pixel stepping. The native policy uses four-neighbor connectivity, floored mapped seed coordinates, RGB composited over the white display backdrop, and a half-alpha threshold for visible clip pixels. Clipped flood coverage then feeds the existing brush/composition path. It adds no persistent process or document-derived filesystem access.

Work and format limits

Native union/frame input is bounded to 4,096 rectangles per call and 65,536 aggregate, with 131,072 normalized points and aggregate frame edges. Source records retain separate parsed-count limits. Logical coordinates have a finite absolute limit of one billion and frame widths one million. The larger source format domains are not all accepted merely because framing succeeds.

Flood work shares the raster adapter's per-call 16,777,216-pixel and aggregate 33,554,432-composite/67,108,864-rendered-pixel budgets. Its queue has at most one entry per pixel; the 24-byte-per-pixel estimate must fit the existing 256 MiB work bound. Existing call, markup, input/output and helper-deadline limits remain. Palette-index colors use the selected palette; unavailable colors and CLR_INVALID produce no flood paint. The true-color adapter accepts PALETTERGB's RGB value.

Acceptance boundary

The batch includes independent geometry/color assertions and offscreen native comparison/conflict consumers. No rendering tests ran during implementation. The dated record separates subsequent actual painting/consumer checks from source review. Remaining all-format, signed/distribution, physical image/Finder, font/palette, minimum-OS and physical Intel acceptance require their own evidence. Parsing or successful SVG output alone does not prove correct painting.