Use layout width (without trailing white space)

Author: tomcur

parley/src/layout/alignment.rs

@@ -15,13 +15,19 @@ pub(crate) fn align<B: Brush>(
 ) {
     // Whether the text base direction is right-to-left.
     let is_rtl = layout.base_level & 1 == 1;
-    let alignment_width = alignment_width.unwrap_or(layout.full_width);
+    let alignment_width = alignment_width.unwrap_or(layout.width);
 
     // Apply alignment to line items
     for line in &mut layout.lines {
         // TODO: remove this field
         line.alignment = alignment;
 
+        if is_rtl {
+            // In RTL text, trailing whitespace is on the left. As we hang that whitespace, offset
+            // the line to the left.
+            line.metrics.offset = -line.metrics.trailing_whitespace;
+        }
+
         // Compute free space.
         let free_space = alignment_width - line.metrics.advance + line.metrics.trailing_whitespace;
 
@@ -34,10 +40,10 @@ pub(crate) fn align<B: Brush>(
                 // Do nothing
             }
             (Alignment::Right, _) | (Alignment::Start, true) | (Alignment::End, false) => {
-                line.metrics.offset = free_space;
+                line.metrics.offset += free_space;
             }
             (Alignment::Middle, _) => {
-                line.metrics.offset = free_space * 0.5;
+                line.metrics.offset += free_space * 0.5;
             }
             (Alignment::Justified, _) => {
                 // Justified alignment doesn't have any effect if free_space is negative or zero
@@ -50,7 +56,7 @@ pub(crate) fn align<B: Brush>(
                 // case, start-align, i.e., left-align for LTR text and right-align for RTL text.
                 if line.break_reason == BreakReason::None || line.num_spaces == 0 {
                     if is_rtl {
-                        line.metrics.offset = free_space;
+                        line.metrics.offset += free_space;
                     }
                     continue;
                 }
@@ -88,12 +94,6 @@ pub(crate) fn align<B: Brush>(
                     });
             }
         }
-
-        if is_rtl {
-            // In RTL text, trailing whitespace is on the left. As we hang that whitespace, offset
-            // the line to the left.
-            line.metrics.offset -= line.metrics.trailing_whitespace;
-        }
     }
 }