emfsvg converts Microsoft Enhanced Metafile (EMF) documents to SVG using the [emf](https://github.com/claricle/emf) gem’s domain model. It is a clean-room Ruby replacement for the FFI wrapper around the GPLv2 libemf2svg C library.

Synopsis

require "emfsvg"

svg = Emfsvg.from_file("image.emf")
svg = Emfsvg.from_bytes(emf_bytes, width: 400, height: 300)
metafile = Emf.parse(emf_bytes)
svg = Emfsvg.to_svg(metafile, namespace: "svg")

Command-line tool

emfsvg convert INPUT.emf OUTPUT.svg [options]

Options:

-w, --width PIXELS      Override viewport width
-h, --height PIXELS     Override viewport height
-n, --namespace NAME    XML namespace prefix (e.g. svg)
-v, --verbose           Print record-by-record dispatch to STDERR
    --emf-plus          Render EMF+ records instead of EMF fallback

Architecture

emfsvg adds a renderer layer on top of `emf’s domain model:

Emf::Model::Metafile
     v
Emfsvg::Renderer
     v
Emfsvg::Visitors::EmrVisitor
     v
Emfsvg::SvgBuilder (XML)
     v
Emfsvg::DeviceContext (GDI state)
     v
Emfsvg::ObjectTable (1-indexed pen/brush/font handles)

The renderer walks the metafile’s records, dispatching each to a visit_<record_type> method on the visitor. State changes (pen, brush, transform, clip) flow through the DeviceContext; persistent objects are stored in the ObjectTable.

Handlers

The visitor handles a useful subset of EMF records out of the box:

• Primitives: Rectangle, Ellipse, RoundRect, LineTo, MoveToEx, Arc (stub), Polygon, Polyline + 16-bit variants

• Paths: BeginPath/EndPath/CloseFigure/FillPath/StrokePath/ StrokeAndFillPath/AbortPath

• State: SetTextColor, SetBkColor, SetBkMode, SetMapMode, SetRop2, SetPolyFillMode, SetTextAlign, SetStretchBltMode

• Transform: SetWorldTransform, ModifyWorldTransform

• Objects: CreatePen, CreateBrushIndirect, SelectObject, DeleteObject, SaveDc, RestoreDc

• Misc: SetMiterLimit, SetWindowExtEx, SetViewportExtEx

Unsupported record types fall through silently (verbose mode logs them).

Sparx/Wine Y-repair

EMFs from Sparx Enterprise Architect under Wine have only the Y anchor negated. The detector (rclBounds.top * rclBounds.bottom < 0) and the per-coordinate repair live in Emfsvg::Renderer and Emfsvg::Visitors::EmrVisitor#maybe_flip_y, matching the behaviour of the C library.

Installation

gem install emfsvg

Or in your Gemfile:

gem "emfsvg", "~> 0.1"
gem "emf", "~> 0.1"

Requires Ruby >= 3.1.

Development

git clone https://github.com/claricle/emfsvg
cd emfsvg
bundle install
bundle exec rspec
bundle exec rubocop

Status

EMF-to-SVG renders the common subset of records from the EMF fixtures. Bitmap records (StretchDIBits, AlphaBlend, etc.) and EMF+ drawing records are not yet rendered. Corrupted inputs are resilient through the emf parser’s hardened error handling.

License

BSD-2-Clause. See LICENSE.txt.