author-info-blocks: automate png generation of sample doc

A PDF document is generated from the sample Markdown file and then
converted to PNG via ImageMagick.

The dependency used for PDF conversions seems to be a security nightmare
when used on untrusted input, it is disabled on most systems but must be
enabled for the make targets to build correctly.

Author: tarleb

author-info-blocks/.gitignore

@@ -0,0 +1 @@
+/sample.pdf

author-info-blocks/Makefile

@@ -7,4 +7,14 @@ test: sample.md author-info-blocks.lua
 expected.native: sample.md author-info-blocks.lua
 	pandoc --lua-filter=author-info-blocks.lua --standalone --output $@ $<
 
+sample.pdf: sample.md author-info-blocks.lua
+	@pandoc \
+	    --lua-filter=author-info-blocks.lua \
+	    --output $@ $<
+
+sample.png: sample.pdf
+	@# somewhat crude method of converting to PDF, removing the page number
+	@# and trimming the image to the title block.
+	@convert -density 300 $< -shave 0%x15% -trim -border 5% $@
+
 .PHONY: test

author-info-blocks/README.md

@@ -56,4 +56,4 @@ This will mark Jane Doe and John Q. Doe as equal contributors and
 Jane Doe as the sole corresponding author. Below is a screenshot
 of a document header created from this metadata.
 
-![example document screenshot](document-screenshot.jpg)
+![sample output](sample.png)