diff --git a/dyesub-tool/src/main.rs b/dyesub-tool/src/main.rs
index e570512..be40312 100644
--- a/dyesub-tool/src/main.rs
+++ b/dyesub-tool/src/main.rs
@@ -1,53 +1,10 @@
 pub mod svg;
-use svg::*;
 
-use askama::Template;
-use derive_more::From;
-use lazy_static::lazy_static;
-use std::{fs::OpenOptions, io::Write};
+mod render;
 
-#[derive(Template)]
-#[template(path = "document.xml")]
-struct DocumentTemplate<'a> {
-    dimensions: &'a DocumentDimensions,
-    keyboard: kle_serial::Keyboard,
-}
-
-struct DocumentDimensions {
-    width: SVGMeasure,
-    height: SVGMeasure,
-    margin: SVGMeasure,
-}
-
-fn kle_font_units(kle_font_units: &usize) -> SVGMeasure {
-    SVGMeasure::new((6 + kle_font_units * 2) as f64, SVGUnit::Pixel)
-}
-
-lazy_static! {
-    static ref LETTER_LANDSCAPE: DocumentDimensions = DocumentDimensions {
-        width: SVGMeasure::new(11.0, SVGUnit::Inch),
-        height: SVGMeasure::new(8.5, SVGUnit::Inch),
-        margin: SVGMeasure::new(0.25, SVGUnit::Inch),
-    };
-}
-
-#[derive(From, Debug)]
-enum Error {
-    Io(std::io::Error),
-    Template(askama::Error),
-    LayoutParse(serde_json::Error),
-}
+use render::{render_file, Result};
 
-fn main() -> Result<(), Error> {
-    let mut file = OpenOptions::new()
-        .write(true)
-        .truncate(true)
-        .create(true)
-        .open("output.svg")?;
-    let document = DocumentTemplate {
-        dimensions: &LETTER_LANDSCAPE,
-        keyboard: serde_json::from_str(&std::fs::read_to_string("layout.json")?)?,
-    };
-    write!(file, "{}", document.render()?)?;
+fn main() -> Result<()> {
+    render_file("layout.json", "output.svg")?;
     Ok(())
 }
diff --git a/dyesub-tool/src/render.rs b/dyesub-tool/src/render.rs
new file mode 100644
index 0000000..16ffbd7
--- /dev/null
+++ b/dyesub-tool/src/render.rs
@@ -0,0 +1,65 @@
+use std::path::Path;
+
+use askama::Template;
+use derive_more::From;
+use lazy_static::lazy_static;
+
+use crate::svg::{SVGMeasure, SVGUnit};
+
+#[derive(Template)]
+#[template(path = "document.xml")]
+struct DocumentTemplate<'a> {
+    dimensions: &'a DocumentDimensions,
+    keyboard: kle_serial::Keyboard,
+}
+
+struct DocumentDimensions {
+    width: SVGMeasure,
+    height: SVGMeasure,
+    margin: SVGMeasure,
+}
+
+lazy_static! {
+    static ref LETTER_LANDSCAPE: DocumentDimensions = DocumentDimensions {
+        width: SVGMeasure::new(11.0, SVGUnit::Inch),
+        height: SVGMeasure::new(8.5, SVGUnit::Inch),
+        margin: SVGMeasure::new(0.25, SVGUnit::Inch),
+    };
+}
+
+mod filters {
+    use crate::svg::{SVGMeasure, SVGUnit};
+
+    pub fn kle_font_units(kle_font_units: &usize) -> askama::Result<SVGMeasure> {
+        Ok(SVGMeasure::new((6 + kle_font_units * 2) as f64, SVGUnit::Pixel))
+    }
+}
+
+#[derive(From, Debug)]
+pub enum Error {
+    Io(std::io::Error),
+    Template(askama::Error),
+    LayoutParse(serde_json::Error),
+}
+
+pub type Result<T> = std::result::Result<T, Error>;
+
+pub fn render_file<P, Q>(input_path: P, output_path: Q) -> Result<()>
+where P: AsRef<Path>, Q: AsRef<Path> {
+    use std::{fs::{self, OpenOptions}, io::Write};
+    let mut file = OpenOptions::new()
+        .write(true)
+        .truncate(true)
+        .create(true)
+        .open(output_path)?;
+    write!(file, "{}", render(&fs::read_to_string(input_path)?)?)?;
+    Ok(())
+}
+
+pub fn render(input: &str) -> Result<String> {
+    let document = DocumentTemplate {
+        dimensions: &LETTER_LANDSCAPE,
+        keyboard: serde_json::from_str(input)?,
+    };
+    Ok(document.render()?)
+}
\ No newline at end of file
diff --git a/dyesub-tool/templates/document.xml b/dyesub-tool/templates/document.xml
index be9847b..5995dcc 100644
--- a/dyesub-tool/templates/document.xml
+++ b/dyesub-tool/templates/document.xml
@@ -4,8 +4,8 @@
   <defs>
     <style type="text/css"><![CDATA[@import url('https://fonts.googleapis.com/css2?family=M+PLUS+Rounded+1c:wght@700&display=swap');]]></style>
   </defs>
-  {% let u = crate::svg::SVGMeasure::new(14.0, crate::svg::SVGUnit::Millimeter) %}
-  {% let padding = crate::svg::SVGMeasure::new(2.5, crate::svg::SVGUnit::Millimeter) %}
+  {% let u = SVGMeasure::new(14.0, SVGUnit::Millimeter) %}
+  {% let padding = SVGMeasure::new(2.5, SVGUnit::Millimeter) %}
   {% let dy = "0.125em" %}
   {% for key in keyboard.keys %}
     {% let x = u * key.x + padding * key.x + dimensions.margin %}
@@ -17,47 +17,47 @@
 
       {# top-left #}
       {% if let Some(legend) = key.legends[0] %}
-        <text x="{{ width * 0.25 }}" y="{{ height * 0.25 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ crate::kle_font_units(legend.size) }}" dy="{{ dy }}">{{ legend.text }}</text>
+        <text x="{{ width * 0.25 }}" y="{{ height * 0.25 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ legend.size|kle_font_units }}" dy="{{ dy }}">{{ legend.text }}</text>
       {% endif %}
 
       {# top-center #}
       {% if let Some(legend) = key.legends[1] %}
-        <text x="{{ width * 0.5 }}" y="{{ height * 0.25 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ crate::kle_font_units(legend.size) }}" dy="{{ dy }}">{{ legend.text }}</text>
+        <text x="{{ width * 0.5 }}" y="{{ height * 0.25 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ legend.size|kle_font_units }}" dy="{{ dy }}">{{ legend.text }}</text>
       {% endif %}
 
       {# top-right #}
       {% if let Some(legend) = key.legends[2] %}
-        <text x="{{ width * 0.75 }}" y="{{ height * 0.25 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ crate::kle_font_units(legend.size) }}" dy="{{ dy }}">{{ legend.text }}</text>
+        <text x="{{ width * 0.75 }}" y="{{ height * 0.25 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ legend.size|kle_font_units }}" dy="{{ dy }}">{{ legend.text }}</text>
       {% endif %}
 
       {# middle-left #}
       {% if let Some(legend) = key.legends[3] %}
-        <text x="{{ width * 0.25 }}" y="{{ height * 0.5 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ crate::kle_font_units(legend.size) }}" dy="{{ dy }}">{{ legend.text }}</text>
+        <text x="{{ width * 0.25 }}" y="{{ height * 0.5 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ legend.size|kle_font_units }}" dy="{{ dy }}">{{ legend.text }}</text>
       {% endif %}
 
       {# middle-center #}
       {% if let Some(legend) = key.legends[4] %}
-        <text x="{{ width * 0.5 }}" y="{{ height * 0.5 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ crate::kle_font_units(legend.size) }}" dy="{{ dy }}">{{ legend.text }}</text>
+        <text x="{{ width * 0.5 }}" y="{{ height * 0.5 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ legend.size|kle_font_units }}" dy="{{ dy }}">{{ legend.text }}</text>
       {% endif %}
 
       {# middle-right #}
       {% if let Some(legend) = key.legends[5] %}
-        <text x="{{ width * 0.75 }}" y="{{ height * 0.5 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ crate::kle_font_units(legend.size) }}" dy="{{ dy }}">{{ legend.text }}</text>
+        <text x="{{ width * 0.75 }}" y="{{ height * 0.5 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ legend.size|kle_font_units }}" dy="{{ dy }}">{{ legend.text }}</text>
       {% endif %}
 
       {# bottom-left #}
       {% if let Some(legend) = key.legends[6] %}
-        <text x="{{ width * 0.25 }}" y="{{ height * 0.75 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ crate::kle_font_units(legend.size) }}" dy="{{ dy }}">{{ legend.text }}</text>
+        <text x="{{ width * 0.25 }}" y="{{ height * 0.75 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ legend.size|kle_font_units }}" dy="{{ dy }}">{{ legend.text }}</text>
       {% endif %}
 
       {# bottom-center #}
       {% if let Some(legend) = key.legends[7] %}
-        <text x="{{ width * 0.55 }}" y="{{ height * 0.75 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ crate::kle_font_units(legend.size) }}" dy="{{ dy }}">{{ legend.text }}</text>
+        <text x="{{ width * 0.55 }}" y="{{ height * 0.75 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ legend.size|kle_font_units }}" dy="{{ dy }}">{{ legend.text }}</text>
       {% endif %}
 
       {# bottom-right #}
       {% if let Some(legend) = key.legends[8] %}
-        <text x="{{ width * 0.75 }}" y="{{ height * 0.75 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ crate::kle_font_units(legend.size) }}" dy="{{ dy }}">{{ legend.text }}</text>
+        <text x="{{ width * 0.75 }}" y="{{ height * 0.75 }}" dominant-baseline="middle" text-anchor="middle" style="font-family: 'M PLUS Rounded 1c'" font-size="{{ legend.size|kle_font_units }}" dy="{{ dy }}">{{ legend.text }}</text>
       {% endif %}
 
       {# TODO 9-11 are side #}