TIKA-4855: Render EMF/WMF through POI and emit the OLE2 SummaryInformation thumbnail - #3095
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TIKA-4855: Render EMF/WMF through POI and emit the OLE2 SummaryInformation thumbnail#3095dschmidt wants to merge 7 commits into
dschmidt wants to merge 7 commits into
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…mation thumbnail
POIMetafileRenderer (poi-metafile-renderer) draws EMF and WMF images to a
PNG of a configurable width; Word's bitmap-in-WMF thumbnails, which POI has
no bounds for, are rendered from the bitmap. EMFParser and WMFParser are
RenderingParsers and emit the rendering as a RENDERING embedded document
with "emf-parser" / "wmf-parser": {"renderImage": true}, off by
default, the way the PDF parser emits page renderings. OfficeParser emits
the SummaryInformation thumbnail of the OLE2 formats (a WMF) as a THUMBNAIL
embedded document, as the OOXML parsers do with the docProps thumbnail.
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…o e.g. thumbnails With "renderOnlyEmbeddedResourceTypes": ["THUMBNAIL"] the parsers render the document's thumbnail but not the metafiles of embedded objects or pictures; empty (the default) renders every image.
# Conflicts: # CHANGES.txt
# Conflicts: # CHANGES.txt
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August 30, 2026 11:14
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Office documents carry their preview image as a vector metafile: the OOXML
docProps/thumbnail.emfof Word (an EMF wrapping a WMF) andthumbnail.wmfof Excel, and the SummaryInformation thumbnail (PIDSI_THUMBNAIL,CF_METAFILEPICT, a WMF) of the OLE2 formats. Neither is usable as a preview outside Windows, and outside the JVM there is no maintained EMF/WMF rasterizer, while POI's HEMF/HWMF can draw both.Following the PDF parser's rendering design:
POIMetafileRenderer(poi-metafile-renderer) is aRendererforimage/emfandimage/wmf: the POI picture drawn onto a white canvas, a PNG of a configurable width. The WMF thumbnails Word writes consist of asetWindowExtand adibStretchBltrecord only, for which POI cannot compute bounds; those are rendered from the record's bitmap.EMFParserandWMFParserimplementRenderingParserand, with"emf-parser"/"wmf-parser": {"renderImage": true, "renderWidth": 800}(off by default), emit the rendering as aRENDERINGembedded document named after the image. An injected renderer is used when it supports the type, the POI one otherwise. The shared config and emission live inMetafileParserConfigandMetafileRendering.OfficeParseremits the SummaryInformation thumbnail as aTHUMBNAILembedded document (image/wmf,thumbnail.wmf), consistent with the docProps thumbnail of the OOXML parsers. Two PowerPoint tests count one embedded document more because of it.Verified against tika-server with
/unpack: docx, xlsx, doc, xls and ppt files that carry a thumbnail yield it at depth 1 and its PNG rendering at depth 2.https://issues.apache.org/jira/browse/TIKA-4855