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| -rw-r--r-- | doc/lua-filters.md | 45 |
1 files changed, 23 insertions, 22 deletions
diff --git a/doc/lua-filters.md b/doc/lua-filters.md index 66e63b439..d9c1debc0 100644 --- a/doc/lua-filters.md +++ b/doc/lua-filters.md @@ -264,32 +264,33 @@ return { } ``` -## Default metadata file +## Center images in LaTeX and HTML output -This filter causes metadata defined in an external file -(`metadata-file.yaml`) to be used as default values in a -document's metadata: +For LaTeX, wrap an image in LaTeX snippets which cause the image +to be centered horizontally. In HTML, the image element's style +attribute is used to achieve centering. ``` lua --- read metadata file into string -local metafile = io.open('metadata-file.yaml', 'r') -local content = metafile:read("*a") -metafile:close() --- get metadata -local default_meta = pandoc.read(content, "markdown").meta +-- Filter images with this function if the target format is LaTeX. +if FORMAT:match 'latex' then + function Image (elem) + -- Surround all images with image-centering raw LaTeX. + return { + pandoc.RawInline('latex', '\\hfill\\break{\\centering'), + elem, + pandoc.RawInline('latex', '\\par}') + } + end +end -return { - { - Meta = function(meta) - -- use default metadata field if it hasn't been defined yet. - for k, v in pairs(default_meta) do - if meta[k] == nil then - meta[k] = v - end - end - return meta - end, - } +-- Filter images with this function if the target format is HTML +if FORMAT:match 'html' then + function Image (elem) + -- Use CSS style to center image + elem.attributes.style = 'margin:auto; display: block;' + return elem + end +end ``` ## Setting the date in the metadata |