Fix horizontal text alignment

core/src/renderer/null.rs

@@ -87,8 +87,8 @@ impl text::Paragraph for () {
         text::Difference::None
     }
 
-    fn horizontal_alignment(&self) -> alignment::Horizontal {
-        alignment::Horizontal::Left
+    fn horizontal_alignment(&self) -> Option<alignment::Horizontal> {
+        None
     }
 
     fn vertical_alignment(&self) -> alignment::Vertical {

core/src/text.rs

@@ -34,7 +34,7 @@ pub struct Text<Content = String, Font = crate::Font> {
     pub font: Font,
 
     /// The horizontal alignment of the [`Text`].
-    pub horizontal_alignment: alignment::Horizontal,
+    pub horizontal_alignment: Option<alignment::Horizontal>,
 
     /// The vertical alignment of the [`Text`].
     pub vertical_alignment: alignment::Vertical,

core/src/text/paragraph.rs

@@ -24,7 +24,7 @@ pub trait Paragraph: Sized + Default {
     fn compare(&self, text: Text<(), Self::Font>) -> Difference;
 
     /// Returns the horizontal alignment of the [`Paragraph`].
-    fn horizontal_alignment(&self) -> alignment::Horizontal;
+    fn horizontal_alignment(&self) -> Option<alignment::Horizontal>;
 
     /// Returns the vertical alignment of the [`Paragraph`].
     fn vertical_alignment(&self) -> alignment::Vertical;
@@ -108,7 +108,7 @@ impl<P: Paragraph> Plain<P> {
     }
 
     /// Returns the horizontal alignment of the [`Paragraph`].
-    pub fn horizontal_alignment(&self) -> alignment::Horizontal {
+    pub fn horizontal_alignment(&self) -> Option<alignment::Horizontal> {
         self.raw.horizontal_alignment()
     }
 

core/src/widget/text.rs

@@ -67,7 +67,7 @@ where
     line_height: LineHeight,
     width: Length,
     height: Length,
-    horizontal_alignment: alignment::Horizontal,
+    horizontal_alignment: Option<alignment::Horizontal>,
     vertical_alignment: alignment::Vertical,
     font: Option<Renderer::Font>,
     shaping: Shaping,
@@ -89,7 +89,7 @@ where
             font: None,
             width: Length::Shrink,
             height: Length::Shrink,
-            horizontal_alignment: alignment::Horizontal::Left,
+            horizontal_alignment: None,
             vertical_alignment: alignment::Vertical::Top,
             shaping: Shaping::default(),
             wrapping: Wrapping::default(),
@@ -140,7 +140,7 @@ where
         mut self,
         alignment: impl Into<alignment::Horizontal>,
     ) -> Self {
-        self.horizontal_alignment = alignment.into();
+        self.horizontal_alignment = Some(alignment.into());
         self
     }
 
@@ -290,7 +290,7 @@ pub fn layout<Renderer>(
     line_height: LineHeight,
     size: Option<Pixels>,
     font: Option<Renderer::Font>,
-    horizontal_alignment: alignment::Horizontal,
+    horizontal_alignment: Option<alignment::Horizontal>,
     vertical_alignment: alignment::Vertical,
     shaping: Shaping,
     wrapping: Wrapping,
@@ -345,9 +345,9 @@ pub fn draw<Renderer>(
     let bounds = layout.bounds();
 
     let x = match paragraph.horizontal_alignment() {
-        alignment::Horizontal::Left => bounds.x,
-        alignment::Horizontal::Center => bounds.center_x(),
-        alignment::Horizontal::Right => bounds.x + bounds.width,
+        None | Some(alignment::Horizontal::Left) => bounds.x,
+        Some(alignment::Horizontal::Center) => bounds.center_x(),
+        Some(alignment::Horizontal::Right) => bounds.x + bounds.width,
     };
 
     let y = match paragraph.vertical_alignment() {