propertiesView: Use image dimensions from decoder

This also shows the units for SVG dimensions if not pixels.

Issue #43

Part-of: <https://gitlab.gnome.org/Incubator/loupe/-/merge_requests/136>

src/decoder/formats/mod.rs

@@ -33,3 +33,10 @@ impl std::fmt::Display for ImageFormat {
         }
     }
 }
+
+#[derive(Clone, Debug, Default)]
+pub enum ImageDimensionDetails {
+    Svg((rsvg::Length, rsvg::Length)),
+    #[default]
+    None,
+}

src/decoder/formats/svg.rs

@@ -58,7 +58,11 @@ impl Svg {
 
             let (original_width, original_height) = svg_dimensions(&renderer);
 
-            tiles.set_original_dimensions((original_width, original_height));
+            let intrisic_dimensions = renderer.intrinsic_dimensions();
+            tiles.set_original_dimensions_full(
+                (original_width, original_height),
+                ImageDimensionDetails::Svg((intrisic_dimensions.width, intrisic_dimensions.height)),
+            );
 
             loop {
                 let tile_request = {