API

All functions are named exports of emf-converter.

convertMetafileToDataUrl

function convertMetafileToDataUrl(buffer: ArrayBuffer, options?: EmfConvertOptions): Promise<string | null>;

Converts an EMF or WMF file to a PNG data URL. Returns null if the buffer is not a valid metafile, or, in plain Node.js, if the drawing contains text and neither fonts nor @napi-rs/canvas is available.

EmfConvertOptions

Option	Type	Default	Description
maxWidth	number		Maximum output width in pixels. The aspect ratio is preserved.
maxHeight	number		Maximum output height in pixels.
dpiScale	number	1	Resolution multiplier, clamped to 4.
wmfReferenceDpi	number | { x: number; y: number }	96	Playback-device resolution for WMF physical map modes. Supply the original device DPI when known; values must be finite and positive.
maxCanvasDimension	number	8192	Upper limit for output width and height in pixels.
maxRecords	number	200000 / 500000	Records processed per stream before replay stops. EMF+ uses the higher default.
gdiAntialias	boolean	false	Smooth shape edges with canvas antialiasing instead of reproducing GDI/GDI+ rasterisation.
fonts	Array<ArrayBuffer | ArrayBufferView>		TrueType (.ttf, .ttc) and raster (.fon, .fnt) font files used for GDI text rendering.
fontSmoothing	'cleartype' | 'gray' | 'mono'	'cleartype'	Rendering used for fonts with DEFAULT_QUALITY, DRAFT_QUALITY or PROOF_QUALITY.
fontFamilyMap	Record<string, string>		Used without fonts. Maps Windows face names (case-insensitive) to local font families, for example { calibri: 'Carlito' }.

DEFAULT_DPI_SCALE is exported as the default value of dpiScale (1).

SVG functions

function convertMetafileToSvg(buffer: ArrayBuffer, options?: SvgConvertOptions): Promise<string | null>;
function convertMetafileToSvgDataUrl(buffer: ArrayBuffer, options?: SvgConvertOptions): Promise<string | null>;
function convertMetafileToSvgTree(buffer: ArrayBuffer, options?: SvgConvertOptions): Promise<SvgNode | null>;

Function	Returns
convertMetafileToSvg	Standalone SVG markup.
convertMetafileToSvgDataUrl	A data:image/svg+xml;base64,... URL.
convertMetafileToSvgTree	An SvgNode tree for the helpers below.

SvgConvertOptions

Extends EmfConvertOptions.

Option	Type	Default	Description
gdiAntialias	boolean	true	false embeds the aliased GDI shape pixels as image patches instead of smooth vector edges.
exactRasterOps	boolean	true	false skips the raster mirror and approximates destination-reading raster operations with SVG mix-blend-mode.
imageResampling	'renderer' | 'exact'	'renderer'	'exact' renders EMF+ DrawImage at device resolution with the GDI+ resampling kernel instead of letting the SVG renderer scale the image.
includeSize	boolean	true	Emit width and height on the root <svg>. viewBox is always emitted.
idPrefix	string	emf1-, emf2-, ...	Prefix for generated element ids. Use a unique value per inlined SVG.

SvgNode helpers

interface SvgNode {
	tag: string;
	attrs: Record<string, string | number>;
	children?: SvgNode[];
	text?: string;
}

function svgTreeToString(node: SvgNode): string;
function svgTreeToDataUrl(node: SvgNode): string;
function svgTreeToReact<E>(node: SvgNode, createElement: CreateElement<E>, rootProps?: Record<string, unknown>): E;
function svgTreeToJsx(node: SvgNode, options?: SvgJsxOptions): string;

type CreateElement<E> = (type: string, props: Record<string, unknown> | null, ...children: unknown[]) => E;

Function	Description
svgTreeToString	SVG markup for a tree.
svgTreeToDataUrl	Base64 SVG data URL for a tree.
svgTreeToReact	Elements built with createElement (for example React.createElement). rootProps are merged onto the root <svg>.
svgTreeToJsx	Source code of a JSX or TSX component.

SvgJsxOptions

Option	Type	Default	Description
componentName	string	'Metafile'	Name of the generated component.
typescript	boolean	true	Emit TypeScript with SVGProps<SVGSVGElement> typing.
spreadProps	boolean	true	Spread the component props onto the root <svg> after the recorded attributes, so width and height can be overridden.

loadSystemFonts

function loadSystemFonts(options?: LoadSystemFontsOptions): Promise<Uint8Array[]>;

Reads installed .ttf, .ttc, .fon and .fnt files for use with the fonts option. Node.js only; in other environments it returns an empty array.

LoadSystemFontsOptions

Option	Type	Default	Description
dirs	string[]	Platform font folders	Directories to scan. Missing directories are skipped.
filter	(path: string, name: string) => boolean		Keep only files for which this returns true. name is the lower-case file name.
maxDepth	number	4	Subdirectory depth to scan. 0 scans only the listed directories.

The default directories are:

• Windows: %WINDIR%\Fonts and %LOCALAPPDATA%\Microsoft\Windows\Fonts
• Linux: /usr/share/fonts, /usr/local/share/fonts, ~/.fonts, ~/.local/share/fonts
• macOS: /Library/Fonts, /System/Library/Fonts, ~/Library/Fonts

Supported records

EMF

Shapes, paths, blits, clipping, transforms, EMR_EXTTEXTOUTA/W, EMR_POLYTEXTOUTA/W, EMR_SMALLTEXTOUT and text justification, plus:

• Logical palettes (PALETTEINDEX, DIBPALETTEINDEX, PALETTERGB, DIB_PAL_COLORS)
• EMR_ALPHABLEND, EMR_TRANSPARENTBLT, EMR_MASKBLT, EMR_PLGBLT, EMR_SETDIBITSTODEVICE
• EMR_GRADIENTFILL (rectangles and triangles)
• EMR_FILLRGN, EMR_FRAMERGN, EMR_INVERTRGN, EMR_PAINTRGN
• EMR_EXTFLOODFILL, EMR_ANGLEARC, EMR_POLYDRAW, EMR_POLYDRAW16
• EMR_FLATTENPATH, EMR_WIDENPATH, EMR_ABORTPATH

Color space, ICM, OpenGL, escape and font driver records are read and ignored, as on a Windows display.

EMF+

All records in MS-EMFPLUS, with 32-bit, compressed 16-bit and relative point data, and all object types: solid, hatch, texture and gradient brushes; pens with caps, joins, dash styles, dash caps, compound lines and custom line caps; paths, regions, bitmap and metafile images, fonts, string formats and image attributes.

Where GDI+ behaves differently from the MS-EMFPLUS specification (relative points, StrokeFillPath, SetTSGraphics, SetTSClip), the converter follows GDI+.

WMF

META_ANIMATEPALETTE, META_ARC, META_BITBLT, META_CHORD, META_CREATEBITMAP, META_CREATEBITMAPINDIRECT, META_CREATEBRUSH, META_CREATEBRUSHINDIRECT, META_CREATEFONTINDIRECT, META_CREATEPALETTE, META_CREATEPATTERNBRUSH, META_CREATEPENINDIRECT, META_CREATEREGION, META_DELETEOBJECT, META_DIBBITBLT, META_DIBCREATEPATTERNBRUSH, META_DIBSTRETCHBLT, META_ELLIPSE, META_EOF, META_ESCAPE, META_EXCLUDECLIPRECT, META_EXTFLOODFILL, META_EXTTEXTOUT, META_FILLREGION, META_FLOODFILL, META_FRAMEREGION, META_INTERSECTCLIPRECT, META_INVERTREGION, META_LINETO, META_MOVETO, META_OFFSETCLIPRGN, META_OFFSETVIEWPORTORG, META_OFFSETWINDOWORG, META_PAINTREGION, META_PATBLT, META_PIE, META_POLYGON, META_POLYLINE, META_POLYPOLYGON, META_REALIZEPALETTE, META_RECTANGLE, META_RESIZEPALETTE, META_RESTOREDC, META_ROUNDRECT, META_SAVEDC, META_SCALEVIEWPORTEXT, META_SCALEWINDOWEXT, META_SELECTCLIPREGION, META_SELECTOBJECT, META_SELECTPALETTE, META_SETBKCOLOR, META_SETBKMODE, META_SETDIBTODEV, META_SETLAYOUT, META_SETMAPMODE, META_SETMAPPERFLAGS, META_SETPALENTRIES, META_SETPIXEL, META_SETPOLYFILLMODE, META_SETRELABS, META_SETROP2, META_SETSTRETCHBLTMODE, META_SETTEXTALIGN, META_SETTEXTCHAREXTRA, META_SETTEXTCOLOR, META_SETTEXTJUSTIFICATION, META_SETVIEWPORTEXT, META_SETVIEWPORTORG, META_SETWINDOWEXT, META_SETWINDOWORG, META_STRETCHBLT, META_STRETCHDIB, META_TEXTOUT.

An EMF embedded in MFCOMMENT escape records is played instead of the WMF records, as Windows does. Where current Windows versions play a record differently from the MS-WMF specification (Win16 device bitmaps in META_BITBLT and META_STRETCHBLT, META_CREATEPATTERNBRUSH, banded META_SETDIBTODEV), the converter follows Windows.