load fontdb in query_all so that we can measure text files (#55)

* load fontdb in query_all so that we can measure text files

Author: tmbb

native/resvg/src/lib.rs

@@ -357,11 +357,19 @@ pub fn query_all<'a>(env: Env<'a>, in_svg: String, options: Options) -> NifResul
         env
     );
 
-    let tree = try_or_return_elixir_err!(
+    let mut tree = try_or_return_elixir_err!(
         usvg::Tree::from_xmltree(&xml_tree, &parsed_options.usvg).map_err(|e| e.to_string()),
         env
     );
 
+    // fontdb initialization is pretty expensive, so perform it only when needed.
+    if tree.has_text_nodes() {
+        match load_fonts(&parsed_options) {
+            Ok(fontdb) => tree.convert_text(&fontdb),
+            Err(error) => return Ok((atoms::error(), error).encode(env)),
+        };
+    }
+
     fn round_len(v: f32) -> f32 {
         (v * 1000.0).round() / 1000.0
     }

test/resvg_test.exs

@@ -171,5 +171,28 @@ defmodule Resvg.Test do
                  height: 613.6170043945312
                }
     end
+
+    test "measures text elements if the right font files are given" do
+      roboto = font_file("Roboto/Roboto-Regular.ttf")
+
+      input = image_path("text-measurement.svg")
+
+      [node] = Resvg.query_all(input, font_files: [roboto], resources_dir: @tmp)
+
+      assert node ==
+               %Resvg.Native.Node{
+                 id: "Text-Element-1",
+                 x: 0.28700000047683716,
+                 y: -8.531000137329102,
+                 width: 85.18399810791016,
+                 height: 8.64799976348877
+               }
+    end
+
+    test "doesn't measure text elements if the right font files are not given" do
+      input = image_path("text-measurement.svg")
+
+      assert Resvg.query_all(input, font_files: []) == []
+    end
   end
 end