Implement textual hit testing

graphics/src/backend.rs

@@ -1,7 +1,7 @@
 //! Write a graphics backend.
 use iced_native::image;
 use iced_native::svg;
-use iced_native::{Font, Size};
+use iced_native::{Font, HitTestResult, Point, Size};
 
 /// The graphics backend of a [`Renderer`].
 ///
@@ -43,6 +43,23 @@ pub trait Text {
         font: Font,
         bounds: Size,
     ) -> (f32, f32);
+
+    /// Tests whether the provided point is within the boundaries of [`Text`]
+    /// laid out with the given parameters, returning information about
+    /// the nearest character.
+    ///
+    /// If nearest_only is true, the hit test does not consider whether the
+    /// the point is interior to any glyph bounds, returning only the character
+    /// with the nearest centeroid.
+    fn hit_test(
+        &self,
+        contents: &str,
+        size: f32,
+        font: Font,
+        bounds: Size,
+        point: Point,
+        nearest_only: bool,
+    ) -> HitTestResult;
 }
 
 /// A graphics backend that supports image rendering.