Port px & em dpi fix from #48

Author: sameer

lib/src/converter/mod.rs

@@ -402,10 +402,10 @@ fn length_to_mm(l: svgtypes::Length, dpi: f64, scale: Option<f64>) -> f64 {
         In => Length::new::<inch>(l.number),
         Pc => Length::new::<pica_computer>(l.number) / dpi_scaling,
         Pt => Length::new::<point_computer>(l.number) / dpi_scaling,
-        Px => Length::new::<inch>(l.number / dpi_scaling),
+        Px => Length::new::<inch>(l.number / dpi),
         Em => {
             warn!("Converting from em to millimeters assumes 1em = 16px");
-            Length::new::<inch>(16. * l.number / dpi_scaling)
+            Length::new::<inch>(16. * l.number / dpi)
         }
         Percent => {
             if let Some(scale) = scale {