Merge pull request #1822 from iced-rs/basic-shaping

`text::Shaping` strategy selection

3 files changed, 53 insertions, 2 deletions

diff --git a/core/src/renderer/null.rs b/core/src/renderer/null.rs
index 88c58825..22afb058 100644
--- a/core/src/renderer/null.rs
+++ b/core/src/renderer/null.rs
@@ -62,6 +62,7 @@ impl text::Renderer for Null {
         _size: f32,
         _font: Font,
         _bounds: Size,
+        _shaping: text::Shaping,
     ) -> (f32, f32) {
         (0.0, 20.0)
     }
@@ -72,6 +73,7 @@ impl text::Renderer for Null {
         _size: f32,
         _font: Self::Font,
         _bounds: Size,
+        _shaping: text::Shaping,
         _point: Point,
         _nearest_only: bool,
     ) -> Option<text::Hit> {
diff --git a/core/src/text.rs b/core/src/text.rs
index 4c72abc3..c59d8fce 100644
--- a/core/src/text.rs
+++ b/core/src/text.rs
@@ -27,6 +27,33 @@ pub struct Text<'a, Font> {
 
     /// The vertical alignment of the [`Text`].
     pub vertical_alignment: alignment::Vertical,
+
+    /// The [`Shaping`] strategy of the [`Text`].
+    pub shaping: Shaping,
+}
+
+/// The shaping strategy of some text.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
+pub enum Shaping {
+    /// No shaping and no font fallback.
+    ///
+    /// This shaping strategy is very cheap, but it will not display complex
+    /// scripts properly nor try to find missing glyphs in your system fonts.
+    ///
+    /// You should use this strategy when you have complete control of the text
+    /// and the font you are displaying in your application.
+    ///
+    /// This is the default.
+    #[default]
+    Basic,
+    /// Advanced text shaping and font fallback.
+    ///
+    /// You will need to enable this flag if the text contains a complex
+    /// script, the font used needs it, and/or multiple fonts in your system
+    /// may be needed to display all of the glyphs.
+    ///
+    /// Advanced shaping is expensive! You should only enable it when necessary.
+    Advanced,
 }
 
 /// The result of hit testing on text.
@@ -77,11 +104,19 @@ pub trait Renderer: crate::Renderer {
         size: f32,
         font: Self::Font,
         bounds: Size,
+        shaping: Shaping,
     ) -> (f32, f32);
 
     /// Measures the width of the text as if it were laid out in a single line.
-    fn measure_width(&self, content: &str, size: f32, font: Self::Font) -> f32 {
-        let (width, _) = self.measure(content, size, font, Size::INFINITY);
+    fn measure_width(
+        &self,
+        content: &str,
+        size: f32,
+        font: Self::Font,
+        shaping: Shaping,
+    ) -> f32 {
+        let (width, _) =
+            self.measure(content, size, font, Size::INFINITY, shaping);
 
         width
     }
@@ -99,6 +134,7 @@ pub trait Renderer: crate::Renderer {
         size: f32,
         font: Self::Font,
         bounds: Size,
+        shaping: Shaping,
         point: Point,
         nearest_only: bool,
     ) -> Option<Hit>;
diff --git a/core/src/widget/text.rs b/core/src/widget/text.rs
index 3193ba84..f0392168 100644
--- a/core/src/widget/text.rs
+++ b/core/src/widget/text.rs
@@ -24,6 +24,7 @@ where
     horizontal_alignment: alignment::Horizontal,
     vertical_alignment: alignment::Vertical,
     font: Option<Renderer::Font>,
+    shaping: text::Shaping,
     style: <Renderer::Theme as StyleSheet>::Style,
 }
 
@@ -42,6 +43,7 @@ where
             height: Length::Shrink,
             horizontal_alignment: alignment::Horizontal::Left,
             vertical_alignment: alignment::Vertical::Top,
+            shaping: text::Shaping::Basic,
             style: Default::default(),
         }
     }
@@ -98,6 +100,12 @@ where
         self.vertical_alignment = alignment;
         self
     }
+
+    /// Sets the [`text::Shaping`] strategy of the [`Text`].
+    pub fn shaping(mut self, shaping: text::Shaping) -> Self {
+        self.shaping = shaping;
+        self
+    }
 }
 
 impl<'a, Message, Renderer> Widget<Message, Renderer> for Text<'a, Renderer>
@@ -129,6 +137,7 @@ where
             size,
             self.font.unwrap_or_else(|| renderer.default_font()),
             bounds,
+            self.shaping,
         );
 
         let size = limits.resolve(Size::new(width, height));
@@ -156,6 +165,7 @@ where
             theme.appearance(self.style.clone()),
             self.horizontal_alignment,
             self.vertical_alignment,
+            self.shaping,
         );
     }
 }
@@ -180,6 +190,7 @@ pub fn draw<Renderer>(
     appearance: Appearance,
     horizontal_alignment: alignment::Horizontal,
     vertical_alignment: alignment::Vertical,
+    shaping: text::Shaping,
 ) where
     Renderer: text::Renderer,
 {
@@ -205,6 +216,7 @@ pub fn draw<Renderer>(
         font: font.unwrap_or_else(|| renderer.default_font()),
         horizontal_alignment,
         vertical_alignment,
+        shaping,
     });
 }
 
@@ -234,6 +246,7 @@ where
             vertical_alignment: self.vertical_alignment,
             font: self.font,
             style: self.style.clone(),
+            shaping: self.shaping,
         }
     }
 }