1 files changed, 33 insertions, 7 deletions

diff --git a/src/diagrams.rs b/src/diagrams.rs
index 6e0b875..a62553f 100644
--- a/src/diagrams.rs
+++ b/src/diagrams.rs
@@ -59,6 +59,32 @@ lazy_static! {
     static ref JAVA_PATH: Mutex<PathBuf> = Mutex::new(env!("BUILTIN_JAVA_PATH").into());
 }
 
+/// An SVG image.
+///
+/// SVG images are vector images, but we only need to treat them as
+/// opaque blobs of bytes, so we don't try to represent them in any
+/// other way.
+pub struct Svg {
+    data: Vec<u8>,
+}
+
+impl Svg {
+    fn new(data: Vec<u8>) -> Self {
+        Self { data }
+    }
+
+    /// Return slice of the bytes of the image.
+    pub fn data(&self) -> &[u8] {
+        &self.data
+    }
+
+    /// Number of bytes in the binary representation of the image.
+    #[allow(clippy::len_without_is_empty)] // is-empty doesn't make sense
+    pub fn len(&self) -> usize {
+        self.data.len()
+    }
+}
+
 /// A code block with markup for a diagram.
 ///
 /// The code block will be converted to an SVG image using an external
@@ -71,7 +97,7 @@ lazy_static! {
 /// for the trait.
 pub trait DiagramMarkup {
     /// Convert the markup into an SVG.
-    fn as_svg(&self) -> Result<Vec<u8>, SubplotError>;
+    fn as_svg(&self) -> Result<Svg, SubplotError>;
 }
 
 /// A code block with pikchr markup.
@@ -98,12 +124,12 @@ impl PikchrMarkup {
 }
 
 impl DiagramMarkup for PikchrMarkup {
-    fn as_svg(&self) -> Result<Vec<u8>, SubplotError> {
+    fn as_svg(&self) -> Result<Svg, SubplotError> {
         let mut flags = pikchr::PikchrFlags::default();
         flags.generate_plain_errors();
         let image = pikchr::Pikchr::render(&self.markup, self.class.as_deref(), flags)
             .map_err(SubplotError::PikchrRenderError)?;
-        Ok(image.as_bytes().to_vec())
+        Ok(Svg::new(image.as_bytes().to_vec()))
     }
 }
 
@@ -129,7 +155,7 @@ impl DotMarkup {
 }
 
 impl DiagramMarkup for DotMarkup {
-    fn as_svg(&self) -> Result<Vec<u8>, SubplotError> {
+    fn as_svg(&self) -> Result<Svg, SubplotError> {
         let path = DOT_PATH.lock().unwrap().clone();
         let mut child = Command::new(&path)
             .arg("-Tsvg")
@@ -146,7 +172,7 @@ impl DiagramMarkup for DotMarkup {
                 .wait_with_output()
                 .map_err(SubplotError::WaitForChild)?;
             if output.status.success() {
-                Ok(output.stdout)
+                Ok(Svg::new(output.stdout))
             } else {
                 Err(SubplotError::child_failed("dot", &output))
             }
@@ -196,7 +222,7 @@ impl PlantumlMarkup {
 }
 
 impl DiagramMarkup for PlantumlMarkup {
-    fn as_svg(&self) -> Result<Vec<u8>, SubplotError> {
+    fn as_svg(&self) -> Result<Svg, SubplotError> {
         let path = JAVA_PATH.lock().unwrap().clone();
         let mut cmd = Command::new(&path);
         cmd.arg("-Djava.awt.headless=true")
@@ -225,7 +251,7 @@ impl DiagramMarkup for PlantumlMarkup {
                 .wait_with_output()
                 .map_err(SubplotError::WaitForChild)?;
             if output.status.success() {
-                Ok(output.stdout)
+                Ok(Svg::new(output.stdout))
             } else {
                 Err(SubplotError::child_failed("plantuml", &output))
             }