After deadline commit

src/exporter/mod.rs

@@ -49,5 +49,5 @@ pub trait ElementSerializer {
     /// Performs the serialization.
     ///
     /// Writes the serialization on the output and returns Err if an error occured.
-    fn serialize<W: Write>(&self, element: Element, output: &mut W) -> Result<(), ExportError>;
+    fn serialize<W: Write>(&self, element: Element, output: &mut W) -> Result<usize, ExportError>;
 }

src/exporter/obj.rs

@@ -24,31 +24,31 @@ impl ObjElementSerializer {
     }
 
     /// Writes a face to a writable output.
-    pub fn write_face<W: Write>(&self, f: model::Face, output: &mut W) -> Result<(), ExportError> {
+    pub fn face_to_string(&self, f: model::Face) -> String {
+
         if f.a.texture_coordinate.is_none() && f.a.normal.is_none() {
             // Only vertices
-            writeln!(output, "f {} {} {}", f.a.vertex + 1, f.b.vertex + 1, f.c.vertex + 1)?;
+            format!("f {} {} {}", f.a.vertex + 1, f.b.vertex + 1, f.c.vertex + 1)
         } else if f.a.normal.is_none() {
             // Vertices + tex coords
-            writeln!(output, "f {}/{} {}/{} {}/{}",
+            format!("f {}/{} {}/{} {}/{}",
                    f.a.vertex + 1, f.a.texture_coordinate.unwrap() + 1,
                    f.b.vertex + 1, f.b.texture_coordinate.unwrap() + 1,
-                   f.c.vertex + 1, f.c.texture_coordinate.unwrap() + 1)?;
+                   f.c.vertex + 1, f.c.texture_coordinate.unwrap() + 1)
         } else if f.a.texture_coordinate.is_none() {
             // Vertices + normals
-            writeln!(output, "f {}//{} {}//{} {}//{}",
+            format!("f {}//{} {}//{} {}//{}",
                    f.a.vertex + 1, f.a.normal.unwrap() + 1,
                    f.b.vertex + 1, f.b.normal.unwrap() + 1,
-                   f.c.vertex + 1, f.c.normal.unwrap() + 1)?;
+                   f.c.vertex + 1, f.c.normal.unwrap() + 1)
         } else {
             // All
-            writeln!(output, "f {}/{}/{} {}/{}/{} {}/{}/{}",
+            format!("f {}/{}/{} {}/{}/{} {}/{}/{}",
                    f.a.vertex + 1, f.a.texture_coordinate.unwrap() + 1, f.a.normal.unwrap() + 1,
                    f.b.vertex + 1, f.b.texture_coordinate.unwrap() + 1, f.b.normal.unwrap() + 1,
-                   f.c.vertex + 1, f.c.texture_coordinate.unwrap() + 1, f.c.normal.unwrap() + 1)?;
+                   f.c.vertex + 1, f.c.texture_coordinate.unwrap() + 1, f.c.normal.unwrap() + 1)
         }
 
-        Ok(())
     }
 }
 
@@ -67,17 +67,18 @@ impl ElementSerializer for ObjElementSerializer {
     /// let result = String::from_utf8(output).unwrap();
     /// assert_eq!(result, "v 1 2 3\n");
     /// ```
-    fn serialize<W: Write>(&self, element: Element, output: &mut W) -> Result<(), ExportError> {
+    fn serialize<W: Write>(&self, element: Element, output: &mut W) -> Result<usize, ExportError> {
 
-        match element {
-            Vertex(v) => writeln!(output, "v {} {} {}", v.x(), v.y(), v.z())?,
-            TextureCoordinate(vt) => writeln!(output, "vt {} {}", vt.x(), vt.y())?,
-            Normal(n) => writeln!(output, "vn {} {} {}", n.x(), n.y(), n.z())?,
-            Face(f) => self.write_face(f, output)?,
-            UseMaterial(ref n) => writeln!(output, "usemtl {}", n)?,
-            _ => (),
-        }
+        let string = match element {
+            Vertex(v) => format!("v {} {} {}", v.x(), v.y(), v.z()),
+            TextureCoordinate(vt) => format!("vt {} {}", vt.x(), vt.y()),
+            Normal(n) => format!("vn {} {} {}", n.x(), n.y(), n.z()),
+            Face(f) => self.face_to_string(f),
+            UseMaterial(ref n) => format!("usemtl {}", n),
+            _ => return Ok(0),
+        };
 
-        Ok(())
+        writeln!(output, "{}", string)?;
+        Ok(string.len() + 1)
     }
 }