Copy the images into the output.

src/context/dependency.rs

@@ -0,0 +1,36 @@
+use std::path::PathBuf;
+
+use crate::error::CustomError;
+
+use super::RenderContext;
+
+#[derive(Debug)]
+pub(crate) enum Dependency {
+    StaticFile { absolute_path: PathBuf },
+}
+
+impl Dependency {
+    pub(crate) async fn perform(
+        &self,
+        render_context: RenderContext<'_>,
+    ) -> Result<(), CustomError> {
+        match self {
+            Dependency::StaticFile { absolute_path } => {
+                let input_root_directory = render_context.config.get_root_directory();
+                let relative_path_to_file = absolute_path.strip_prefix(input_root_directory)?;
+                let path_to_output = render_context
+                    .output_root_directory
+                    .join(relative_path_to_file);
+                tokio::fs::create_dir_all(
+                    path_to_output
+                        .parent()
+                        .ok_or("Output file should have a containing directory.")?,
+                )
+                .await?;
+                // TODO: If file already exists, either error out or compare hash to avoid duplicate write.
+                tokio::fs::copy(absolute_path, path_to_output).await?;
+                Ok(())
+            }
+        }
+    }
+}

src/context/dependency_manager.rs

@@ -58,4 +58,11 @@ impl DependencyManager {
         });
         Ok(())
     }
+
+    /// Return the dependencies and forget about them.
+    pub(crate) fn take_dependencies(&mut self) -> Vec<Dependency> {
+        let mut dependencies = Vec::new();
+        std::mem::swap(&mut self.dependencies, &mut dependencies);
+        dependencies
+    }
 }