83 lines
3.3 KiB
Markdown
83 lines
3.3 KiB
Markdown
|
title: SVG + Makefile = slide deck
|
||
|
|
summary: "You don't need LibreOffice to prepare your presentation -- or: an introduction to makefiles"
|
||
|
|
published: 2020-06-02
|
||
|
|
|
||
|
|
---
|
||
|
|
|
||
|
|
Text-based slides are boring and not effective. While preparing a presentation for my intermediary
|
||
|
|
thesis' defence, I wanted to create something that would support my story better. I wanted to use
|
||
|
|
graphics instead of words so the language centres of my dear audience's brains could focus on my
|
||
|
|
speech rather than reading. Rather than importing slide-sized graphics in a GUI, I thought
|
||
|
|
a makefile would be a nice way to do the trick.
|
||
|
|
|
||
|
|
Makefiles these days are commonly used as a shell script with multiple entry points. You give it a
|
||
|
|
filename, and it will build that file if its dependencies have been changed. Traditionally
|
||
|
|
makefiles are used for C programs, but there's no reason you can't use them for any build you want.
|
||
|
|
Even this website is updated with a makefile! Want to join me and write one together?
|
||
|
|
|
||
|
|
## Writing the makefile
|
||
|
|
Putting the name of our output file in variables will make it easier to change it later.
|
||
|
|
```makefile
|
||
|
|
OUTPUT = slides.pdf
|
||
|
|
```
|
||
|
|
|
||
|
|
We'll make a list of SVGs in the current directory, and convert it into a list of PDFs targets.
|
||
|
|
Sorting is necessary to be able to place your slides like you want. The `$(:=)` construct is used
|
||
|
|
to go from `%.svg` to `build/%.pdf`.
|
||
|
|
```makefile
|
||
|
|
SLIDES ::= $(sort $(wildcard *.svg))
|
||
|
|
SLIDES_PDF ::= $(SLIDES:%.svg=build/%.pdf)
|
||
|
|
```
|
||
|
|
|
||
|
|
I love this next rule. It teaches make that it should use Inkscape if it needs to create a PDF.
|
||
|
|
`$@` refers to the target (`build/….pdf`), and `$<` refers to the first dependency (`….svg`).
|
||
|
|
Inkscape's `-A filename` option exports to PDF without opening the GUI.
|
||
|
|
**TODO: isn't there a way to automatically depend on all parent directories?**
|
||
|
|
```makefile
|
||
|
|
build/%.pdf: %.svg build
|
||
|
|
inkscape -A "$@" "$<"
|
||
|
|
```
|
||
|
|
|
||
|
|
Now we tell make that the final output can be created from the individual slides.
|
||
|
|
|
||
|
|
Make will recursively make sure that all dependencies are up to date. Because we add the SVG source
|
||
|
|
file as a dependency, it will know that the individual PDF files have to be rebuilt if their source
|
||
|
|
was changed. And if any slide was changed, the end result will be updated too. But if there was no
|
||
|
|
change, it won't. Nothing is rebuilt unnecessarily!
|
||
|
|
|
||
|
|
**TODO: DRY**
|
||
|
|
**TODO: Do we need to fix sh's space disease here?**
|
||
|
|
```makefile
|
||
|
|
$(OUTPUT): $(SLIDES_PDF)
|
||
|
|
pdfjoin $(SLIDES_PDF) -o "$@"
|
||
|
|
```
|
||
|
|
|
||
|
|
If you look at the `build/%.pdf` rule, you see that it depends on `build`. With this simple, final
|
||
|
|
rule, make will know how to create this directory.
|
||
|
|
```makefile
|
||
|
|
build:
|
||
|
|
mkdir -p "$@"
|
||
|
|
```
|
||
|
|
|
||
|
|
It is common to create a `clean` to clean up. Since `clean` is not a file, we have to mark the
|
||
|
|
target as "phony".
|
||
|
|
```makefile
|
||
|
|
.PHONY: clean
|
||
|
|
|
||
|
|
clean:
|
||
|
|
rm -rf "$(OUTPUT)" build/
|
||
|
|
```
|
||
|
|
|
||
|
|
This concludes the Makefile portion of this post.
|
||
|
|
|
||
|
|
**TODO: write about first rule being the default**
|
||
|
|
**TODO: split into 2 posts?**
|
||
|
|
|
||
|
|
## Creating and presenting slides
|
||
|
|
Create one SVG per slide, you can do that in Inkscape. Set the document size to something with the
|
||
|
|
desired aspect ratio. In my experience this is 16:9 for newer projectors and 4:3 for older models.
|
||
|
|
|
||
|
|
To use the resulting slide deck during your presentation, I can recommend
|
||
|
|
[pdfpc](https://pdfpc.github.io/). But any old PDF viewer that has a fullscreen mode will work, of
|
||
|
|
course.
|