Do not require `Copy` for text `StyleSheet::Style`

For most widgets, `Style` only requires `Default`. A few require
`Clone`. Only this one requires `Copy`.

Some of the types in the default theme has a custom variant requiring
`Box<dyn Trait>`, or `Rc<dyn Trait>` to provide `Clone`, but this isn't
possible if `Copy` is required.

It would be good to also address the inconsistency of requiring `Clone`
in some places and not others.

This removes `style/src/text.rs` which is unused in this branch and thus
confusing. If there's a reason to keep it, that can be removed from the
change.

2 files changed, 3 insertions, 23 deletions

diff --git a/core/src/widget/text.rs b/core/src/widget/text.rs
index 485bb542..3193ba84 100644
--- a/core/src/widget/text.rs
+++ b/core/src/widget/text.rs
@@ -153,7 +153,7 @@ where
             &self.content,
             self.size,
             self.font,
-            theme.appearance(self.style),
+            theme.appearance(self.style.clone()),
             self.horizontal_alignment,
             self.vertical_alignment,
         );
@@ -233,7 +233,7 @@ where
             horizontal_alignment: self.horizontal_alignment,
             vertical_alignment: self.vertical_alignment,
             font: self.font,
-            style: self.style,
+            style: self.style.clone(),
         }
     }
 }
@@ -261,7 +261,7 @@ where
 /// The style sheet of some text.
 pub trait StyleSheet {
     /// The supported style of the [`StyleSheet`].
-    type Style: Default + Copy;
+    type Style: Default + Clone;
 
     /// Produces the [`Appearance`] of some text.
     fn appearance(&self, style: Self::Style) -> Appearance;
diff --git a/style/src/text.rs b/style/src/text.rs
deleted file mode 100644
index d5a16bef..00000000
--- a/style/src/text.rs
+++ /dev/null
@@ -1,20 +0,0 @@
-//! Change the appearance of text.
-use crate::core::Color;
-
-/// The style sheet of some text.
-pub trait StyleSheet {
-    /// The supported style of the [`StyleSheet`].
-    type Style: Default + Copy;
-
-    /// Produces the [`Appearance`] of some text.
-    fn appearance(&self, style: Self::Style) -> Appearance;
-}
-
-/// The apperance of some text.
-#[derive(Debug, Clone, Copy, Default)]
-pub struct Appearance {
-    /// The [`Color`] of the text.
-    ///
-    /// The default, `None`, means using the inherited color.
-    pub color: Option<Color>,
-}