Use gifs to improve documentation. (#21)

Former-commit-id: 40e5ccedcf5d1ca8f0d5cc373ba3b3c4cc2d6c6a

docs/gen_gallery.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+ROOT=`stack path --project-root`
+EXAMPLES='boundingbox colormaps goo latex_basic latex_color latex_draw
+          latex_wheel raster sphere sunflower tangent_and_normal vector_field'
+
+WIDTH=640
+HEIGHT=$((WIDTH*9/16))
+FPS=30
+
+SRC_DIR=$ROOT/examples
+DST_DIR=$ROOT/docs/rendered
+OPTS='--fps $FPS --width $WIDTH --height $HEIGHT'
+
+cat << EOF > $ROOT/docs/gallery.md
+# Gallery
+This file is auto-generated by docs/render_all.sh. DO NOT EDIT.
+
+EOF
+
+for e in $EXAMPLES; do
+  cat << EOF >> $ROOT/docs/gallery.md
+## $e
+
+<details>
+  <summary>View $e.hs</summary>
+  <pre><code class="haskell">
+  {!examples/$e.hs!}
+  </code></pre>
+</details>
+<br/>
+<video width="$WIDTH" height="$HEIGHT" autoplay loop>
+  <source src="https://github.com/Lemmih/reanimate/raw/master/docs/rendered/$e.mp4">
+</video>
+
+<br/><hr><br/>
+
+EOF
+
+  SRC_FILE=./$SRC_DIR/$e.hs
+  DST_FILE=./$DST_DIR/$e.mp4
+  if [[ "$SRC_FILE" -nt "$DST_FILE" ]]; then
+    stack $SRC_FILE render --compile -o $DST_FILE $OPTS
+  fi
+done