POI 렌더러 대신 LibreOffice+PDFBox로 교체 (좌표 틀어짐 수정) - #2
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Apache POI's own AWT-based slide renderer (Slide#draw) accumulates positioning errors from font substitution and group/rotation transform calculations, causing shapes, images, and arrows to drift from their true positions. This is a known limitation of poi-4.0.1's rendering engine rather than a bug in this project's own code. Convert via LibreOffice headless (soffice --convert-to pdf) instead, then rasterize each PDF page with PDFBox. LibreOffice uses a real PowerPoint-compatible layout engine, so coordinates match the original file far more closely. - Add SofficeLocator: resolves the soffice binary across Windows/ Linux/macOS, overridable via -Dsoffice.path or SOFFICE_PATH. - Add SofficePdfConverter: runs soffice with an isolated user profile per conversion (avoids profile-lock hangs on concurrent runs). - Add PdfPageRenderer: renders PDF pages to BufferedImage via PDFBox. - Converter's public API (convert(...), Result) is unchanged; only the internals and the pom.xml dependency (poi -> pdfbox) changed. - Remove PPT.java/PPTX.java/SlideShowFactory.java (POI SlideShow loading), now unused since rendering no longer goes through POI. Requires LibreOffice installed on the machine running the conversion.
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문제
Converter.createImages()가 Apache POI의 자체 AWT 렌더러(Slide#draw)로 슬라이드를 직접 그리는데, 폰트 대체(변환 서버에 원본 폰트가 없을 때 AWT가 다른 폰트로 치환)와 그룹/회전 도형의 좌표 변환 계산 과정에서 오차가 누적되어 도형·이미지·화살표 위치가 조금씩 틀어집니다. README에도 이미 언급되어 있던 현상입니다.변경 내용
렌더링 경로를 LibreOffice 기반으로 교체했습니다.
soffice --headless --convert-to pdf로 pptx/ppt를 PDF로 변환 (SofficePdfConverter)-env:UserInstallation임시 프로필 사용-Dsoffice.path,SOFFICE_PATH환경변수, OS별 기본 설치 경로 순으로 자동 탐색 (SofficeLocator) — Windows/Linux/macOS 모두 지원PdfPageRenderer)LibreOffice는 실제 PowerPoint와 호환되는 레이아웃 엔진으로 렌더링하므로, POI 자체 렌더러보다 좌표가 훨씬 정확합니다.
호환성
Converter의 공개 API(convert(File, String, String),Result)는 그대로입니다. 해상도를 직접 지정하고 싶으면convert(file, path, type, zoom)오버로드를, soffice 경로를 직접 지정하고 싶으면new Converter(destDir, sofficePath)생성자를 사용하면 됩니다.pom.xml의 POI 4종 의존성을 PDFBox 하나로 교체했고, 그에 따라 안 쓰이게 된PPT.java/PPTX.java/SlideShowFactory.java를 제거했습니다.필요 조건
변환이 실행되는 PC/서버에 LibreOffice가 설치되어 있어야 합니다. README에 설치 확인 방법과 경로 지정 방법을 추가했습니다.
테스트
mvn compile성공 확인