Avoid potentially double-measuring strings

embedded-graphics · Sep 4, 2023 · fd7295a · fd7295a
1 parent 6912e65
commit fd7295a
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Showing 3 changed files with 16 additions and 13 deletions.
diff --git a/src/rendering/line.rs b/src/rendering/line.rs
@@ -121,11 +121,14 @@ where
         Ok(())
     }
 
-    fn printed_characters(&mut self, st: &str, width: u32) -> Result<(), Self::Error> {
+    fn printed_characters(&mut self, st: &str, width: Option<u32>) -> Result<(), Self::Error> {
         let top_left = self.pos;
-        self.style
+        let render_width = self
+            .style
             .draw_string(st, self.pos, Baseline::Top, self.display)?;
 
+        let width = width.unwrap_or((render_width - top_left).x as u32);
+
         self.pos += Point::new(width.saturating_as(), 0);
 
         let size = Size::new(width, self.style.line_height().saturating_as());

diff --git a/src/rendering/line_iter.rs b/src/rendering/line_iter.rs
@@ -51,7 +51,7 @@ pub trait ElementHandler {
     }
 
     /// A string of printable characters.
-    fn printed_characters(&mut self, _st: &str, _width: u32) -> Result<(), Self::Error> {
+    fn printed_characters(&mut self, _st: &str, _width: Option<u32>) -> Result<(), Self::Error> {
         Ok(())
     }
 
@@ -325,7 +325,7 @@ where
                             let width = handler.measure(c);
                             if self.move_cursor(width.saturating_as()).is_ok() {
                                 if let Some(Token::Break(c, _)) = self.plugin.render_token(token) {
-                                    handler.printed_characters(c, width)?;
+                                    handler.printed_characters(c, Some(width))?;
                                 }
                                 self.consume_token();
                             }
@@ -445,7 +445,7 @@ where
                         // Safety: space_pos must be a character boundary
                         w.get_unchecked(0..space_pos)
                     };
-                    handler.printed_characters(word, handler.measure(word))?;
+                    handler.printed_characters(word, None)?;
                 }
 
                 handler.whitespace("\u{a0}", 1, self.spaces.consume(1))?;
@@ -456,9 +456,7 @@ where
                 }
             }
 
-            None => {
-                handler.printed_characters(w, handler.measure(w))?;
-            }
+            None => handler.printed_characters(w, None)?,
         }
 
         Ok(())
@@ -532,9 +530,11 @@ pub(crate) mod test {
             Ok(())
         }
 
-        fn printed_characters(&mut self, st: &str, width: u32) -> Result<(), Self::Error> {
-            self.elements
-                .push(RenderElement::String(st.to_owned(), width));
+        fn printed_characters(&mut self, str: &str, width: Option<u32>) -> Result<(), Self::Error> {
+            self.elements.push(RenderElement::String(
+                str.to_owned(),
+                width.unwrap_or_else(|| self.measure(str)),
+            ));
             Ok(())
         }
 

diff --git a/src/style/mod.rs b/src/style/mod.rs
@@ -398,8 +398,8 @@ impl<'a, S: TextRenderer> ElementHandler for MeasureLineElementHandler<'a, S> {
         Ok(())
     }
 
-    fn printed_characters(&mut self, _: &str, width: u32) -> Result<(), Self::Error> {
-        self.cursor += width;
+    fn printed_characters(&mut self, str: &str, width: Option<u32>) -> Result<(), Self::Error> {
+        self.cursor += width.unwrap_or_else(|| self.measure(str));
         self.pos = self.pos.max(self.cursor);
         self.right = self.pos;
         self.space_count = self.partial_space_count;