Custom highlight support [WIP]

src/highlight.rs

@@ -15,17 +15,19 @@ enum Boundary {
     Select(Style),
     #[cfg(feature = "search")]
     Search(Style),
+    Custom(Style, u8), // style, priority
     End,
 }
 
 impl Boundary {
     fn cmp(&self, other: &Boundary) -> Ordering {
         fn rank(b: &Boundary) -> u8 {
             match b {
-                Boundary::Cursor(_) => 3,
+                Boundary::Cursor(_) => 30,
                 #[cfg(feature = "search")]
-                Boundary::Search(_) => 2,
-                Boundary::Select(_) => 1,
+                Boundary::Search(_) => 20,
+                Boundary::Select(_) => 10,
+                Boundary::Custom(_, p) => *p,
                 Boundary::End => 0,
             }
         }
@@ -38,6 +40,7 @@ impl Boundary {
             Boundary::Select(s) => Some(*s),
             #[cfg(feature = "search")]
             Boundary::Search(s) => Some(*s),
+            Boundary::Custom(s, _) => Some(*s),
             Boundary::End => None,
         }
     }
@@ -156,13 +159,15 @@ impl<'a> LineHighlighter<'a> {
         }
     }
 
-    pub fn selection(
+    // Shared code for selection and custom highlights
+    fn multiline_highlight(
         &mut self,
         current_row: usize,
         start_row: usize,
         start_off: usize,
         end_row: usize,
         end_off: usize,
+        boundary: Boundary,
     ) {
         let (start, end) = if current_row == start_row {
             if start_row == end_row {
@@ -180,12 +185,49 @@ impl<'a> LineHighlighter<'a> {
             return;
         };
         if start != end {
-            self.boundaries
-                .push((Boundary::Select(self.select_style), start));
+            self.boundaries.push((boundary, start));
             self.boundaries.push((Boundary::End, end));
         }
     }
 
+    pub fn selection(
+        &mut self,
+        current_row: usize,
+        start_row: usize,
+        start_off: usize,
+        end_row: usize,
+        end_off: usize,
+    ) {
+        self.multiline_highlight(
+            current_row,
+            start_row,
+            start_off,
+            end_row,
+            end_off,
+            Boundary::Select(self.select_style),
+        );
+    }
+
+    pub fn custom(
+        &mut self,
+        current_row: usize,
+        start_row: usize,
+        start_off: usize,
+        end_row: usize,
+        end_off: usize,
+        style: Style,
+        priority: u8,
+    ) {
+        self.multiline_highlight(
+            current_row,
+            start_row,
+            start_off,
+            end_row,
+            end_off,
+            Boundary::Custom(style, priority),
+        );
+    }
+
     pub fn into_spans(self) -> Line<'a> {
         let Self {
             line,

src/textarea.rs

@@ -55,6 +55,13 @@ impl fmt::Display for YankText {
     }
 }
 
+#[derive(Clone, Debug)]
+struct CustomHighlight {
+    range: ((usize, usize), (usize, usize)),
+    style: Style,
+    priority: u8,
+}
+
 /// A type to manage state of textarea. These are some important methods:
 ///
 /// - [`TextArea::default`] creates an empty textarea.
@@ -125,6 +132,7 @@ pub struct TextArea<'a> {
     mask: Option<char>,
     selection_start: Option<(usize, usize)>,
     select_style: Style,
+    custom_highlights: Vec<CustomHighlight>,
 }
 
 /// Convert any iterator whose elements can be converted into [`String`] into [`TextArea`]. Each [`String`] element is
@@ -230,6 +238,7 @@ impl<'a> TextArea<'a> {
             mask: None,
             selection_start: None,
             select_style: Style::default().bg(Color::LightBlue),
+            custom_highlights: Default::default(),
         }
     }
 
@@ -1355,6 +1364,23 @@ impl<'a> TextArea<'a> {
         self.selection_start = None;
     }
 
+    pub fn custom_highlight(
+        &mut self,
+        range: ((usize, usize), (usize, usize)),
+        style: Style,
+        priority: u8,
+    ) {
+        self.custom_highlights.push(CustomHighlight {
+            range,
+            style,
+            priority,
+        });
+    }
+
+    pub fn clear_custom_highlight(&mut self) {
+        self.custom_highlights.clear();
+    }
+
     /// Select the entire text. Cursor moves to the end of the text buffer. When text selection is already ongoing,
     /// it is canceled.
     /// ```
@@ -1612,6 +1638,23 @@ impl<'a> TextArea<'a> {
             hl.selection(row, start.row, start.offset, end.row, end.offset);
         }
 
+        for CustomHighlight {
+            range: ((start_row, start_offset), (end_row, end_offset)),
+            style,
+            priority,
+        } in &self.custom_highlights
+        {
+            hl.custom(
+                row,
+                *start_row,
+                *start_offset,
+                *end_row,
+                *end_offset,
+                *style,
+                *priority,
+            );
+        }
+
         hl.into_spans()
     }