web: document preview transformers configuration

5 files changed, 66 insertions, 13 deletions

diff --git a/website/docs/conf_file.md b/website/docs/conf_file.md
index 339657c..eea35af 100644
--- a/website/docs/conf_file.md
+++ b/website/docs/conf_file.md
@@ -271,6 +271,72 @@ terminal_title: "{file} 🐄"
 terminal_title = "{file} 🐄"
 ```
 
+# Preview
+
+## Transformers
+
+It's possible to define transformers to apply to some files before preview.
+
+This makes it possible for example to render a specific kind of files as images, or to beautify some text ones.
+
+Below are two examples that you may adapt to your needs and prefered tools.
+
+### Render PDF using mutool:
+
+![preview pdf](img/20240706-preview-pdf.png)
+
+```Hjson
+preview_transformers: [
+    # Use mutool to render any PDF file as an image
+    # In this example we use placeholders for the input and output files
+    {
+        input_extensions: [ "pdf" ] // case doesn't matter
+        output_extension: png
+        mode: image
+        command: [ "mutool", "draw", "-o", "{output-path}", "{input-path}" ]
+    }
+]
+```
+
+### Beautify JSON using jq
+
+![preview json](img/20240706-preview-json.png)
+
+```Hjson
+preview_transformers: [
+    # Use jq to beautify JSON
+    # In this example, the command refers to neither the input nor the output,
+    # so broot pipes them to the stdin and stdout of the jq process
+    {
+        input_extensions: [ "json" ]
+        output_extension: json
+        mode: text
+        command: [ "jq" ]
+    }
+]
+```
+
+## Match surroundings
+
+You may limit the filtered view to just the matching lines:
+
+![0 line around match](img/20240706-match-surrounding-0-0.png)
+
+But if you want to have more than just the matching lines displayed in preview, you may set those parameters to
+
+```Hjson
+lines_before_match_in_preview: 1
+lines_after_match_in_preview: 1
+```
+```TOML
+lines_before_match_in_preview = 1
+lines_after_match_in_preview = 1
+```
+
+And you'll get
+
+![1 line around match](img/20240706-match-surrounding-1-1.png)
+
 # Miscellaneous
 
 ## Kitty Graphics
@@ -388,16 +454,3 @@ show_matching_characters_on_path_searches = false
 which gives this:
 
 ![not shown](img/subpath-match-not-shown.png)
-
-## Lines surrounding a match in preview
-
-If you want to have more than just the matching lines displayed in preview, you may changes those parameters in config:
-
-```Hjson
-lines_before_match_in_preview: 0
-lines_after_match_in_preview: 0
-```
-```TOML
-lines_before_match_in_preview = 0
-lines_after_match_in_preview = 0
-```
diff --git a/website/docs/img/20240706-match-surrounding-0-0.png b/website/docs/img/20240706-match-surrounding-0-0.png
new file mode 100644
index 0000000..76bf132
--- /dev/null
+++ b/website/docs/img/20240706-match-surrounding-0-0.png
diff --git a/website/docs/img/20240706-match-surrounding-1-1.png b/website/docs/img/20240706-match-surrounding-1-1.png
new file mode 100644
index 0000000..4cc9c3b
--- /dev/null
+++ b/website/docs/img/20240706-match-surrounding-1-1.png
diff --git a/website/docs/img/20240706-preview-json.png b/website/docs/img/20240706-preview-json.png
new file mode 100644
index 0000000..8d81bf2
--- /dev/null
+++ b/website/docs/img/20240706-preview-json.png
diff --git a/website/docs/img/20240706-preview-pdf.png b/website/docs/img/20240706-preview-pdf.png
new file mode 100644
index 0000000..b2e9d3d
--- /dev/null
+++ b/website/docs/img/20240706-preview-pdf.png