manual: Add cover PDF build to CI

This is not invoked as part of the normal build process, and shouldn't
be: we only ever want to build the cover PDFs when we're uploading them
for printing, and don't want everyone who wants to build Freedoom to
have to install Inkscape. However, we should nonetheless include it in
the CI to check that the build step works.

.github/workflows/make.yml

@@ -18,7 +18,8 @@ jobs:
     - name: Install Prerequisites
       run: |
         sudo apt update
-        sudo apt install python3-pil asciidoc unzip zip ruby dos2unix
+        sudo apt install python3-pil asciidoc unzip zip ruby dos2unix \
+                         inkscape
         sudo gem install asciidoctor-pdf --pre
     - name: Install Deutex
       run: |
@@ -43,6 +44,10 @@ jobs:
           export VERSION=${VERSION:1}
         fi
         echo "VERSION=$VERSION" >> $GITHUB_OUTPUT
+    - name: Make manual cover PDFs
+      run: |
+        cd manual
+        make covers
     - name: Upload Freedoom
       uses: actions/upload-artifact@v4
       with:

manual/Makefile

@@ -11,9 +11,16 @@
 ASCIIDOCTOR_FLAGS = -a pdf-page-size=A5
 MANUAL_ADOC_FILES=$(wildcard freedoom-manual-??.adoc)
 MANUAL_PDF_FILES=$(subst .adoc,.pdf,$(MANUAL_ADOC_FILES))
+COVER_PDF_FILES=cover.pdf
 
 all: $(MANUAL_PDF_FILES)
 
+# We only build the cover PDFs if the user explicitly runs `make covers`;
+# this is because it requires Inkscape and we don't want it as a build
+# dependency. Most users won't ever need these, we only use them when we're
+# uploading the PDF files to print physical manuals.
+covers: $(COVER_PDF_FILES)
+
 freedoom-manual-%.pdf: freedoom-manual-%.adoc
 	-asciidoctor-pdf $(ASCIIDOCTOR_FLAGS) $< -o $@
 
@@ -21,4 +28,4 @@ cover.pdf: cover/cover.svg cover/serpentipede.png cover/minigunner.png
 	inkscape -o $@ $<
 
 clean:
-	$(RM) $(MANUAL_PDF_FILES)
+	$(RM) $(MANUAL_PDF_FILES) $(COVER_PDF_FILES)