Fix off-by-one issue in ScreenLines::iter_line_info_r (#384)

examples/editor/src/main.rs

@@ -13,7 +13,12 @@ use floem::{
 };
 
 fn app_view() -> impl View {
-    let editor_a = text_editor("Hello World!").styling(SimpleStyling::dark());
+    let text = std::env::args()
+        .nth(1)
+        .map(|s| std::fs::read_to_string(s).unwrap());
+    let text = text.as_deref().unwrap_or("Hello world");
+
+    let editor_a = text_editor(text).styling(SimpleStyling::dark());
     let editor_b = editor_a
         .shared_editor()
         .pre_command(|ev| {

src/views/editor/view.rs

@@ -132,7 +132,7 @@ impl ScreenLines {
 
         let end_idx = self.lines.binary_search(r.end()).ok().or_else(|| {
             if self.lines.last().map(|l| r.end() > l).unwrap_or(false) {
-                Some(self.lines.len())
+                Some(self.lines.len() - 1)
             } else {
                 // The end is before the end of our lines but not available
                 None
@@ -1267,3 +1267,83 @@ fn editor_content(
     })
     .style(|s| s.absolute().size_pct(100.0, 100.0))
 }
+
+#[cfg(test)]
+mod tests {
+    use std::{collections::HashMap, rc::Rc};
+
+    use floem_reactive::create_rw_signal;
+    use kurbo::Rect;
+
+    use crate::views::editor::{
+        view::LineInfo,
+        visual_line::{RVLine, VLineInfo},
+    };
+
+    use super::{ScreenLines, ScreenLinesBase};
+
+    #[test]
+    fn iter_line_info_range() {
+        let lines = vec![
+            RVLine::new(10, 0),
+            RVLine::new(10, 1),
+            RVLine::new(10, 2),
+            RVLine::new(10, 3),
+        ];
+        let mut info = HashMap::new();
+        for rv in lines.iter() {
+            info.insert(
+                *rv,
+                LineInfo {
+                    // The specific values don't really matter
+                    y: 0.0,
+                    vline_y: 0.0,
+                    vline_info: VLineInfo::new(0..0, *rv, 4, ()),
+                },
+            );
+        }
+        let sl = ScreenLines {
+            lines: Rc::new(lines),
+            info: Rc::new(info),
+            diff_sections: None,
+            base: create_rw_signal(ScreenLinesBase {
+                active_viewport: Rect::ZERO,
+            }),
+        };
+
+        // Completely outside range should be empty
+        assert_eq!(
+            sl.iter_line_info_r(RVLine::new(0, 0)..=RVLine::new(1, 5))
+                .collect::<Vec<_>>(),
+            Vec::new()
+        );
+        // Should include itself
+        assert_eq!(
+            sl.iter_line_info_r(RVLine::new(10, 0)..=RVLine::new(10, 0))
+                .count(),
+            1
+        );
+        // Typical case
+        assert_eq!(
+            sl.iter_line_info_r(RVLine::new(10, 0)..=RVLine::new(10, 2))
+                .count(),
+            3
+        );
+        assert_eq!(
+            sl.iter_line_info_r(RVLine::new(10, 0)..=RVLine::new(10, 3))
+                .count(),
+            4
+        );
+        // Should only include what is within the interval
+        assert_eq!(
+            sl.iter_line_info_r(RVLine::new(10, 0)..=RVLine::new(10, 5))
+                .count(),
+            4
+        );
+        assert_eq!(
+            sl.iter_line_info_r(RVLine::new(0, 0)..=RVLine::new(10, 5))
+                .count(),
+            4
+        );
+    }
+}

src/views/editor/visual_line.rs

@@ -1454,7 +1454,9 @@ pub struct VLineInfo<L = VLine> {
     pub vline: L,
 }
 impl<L: std::fmt::Debug> VLineInfo<L> {
-    fn new<I: Into<Interval>>(iv: I, rvline: RVLine, line_count: usize, vline: L) -> Self {
+    /// Create a new instance of `VLineInfo`  
+    /// This should rarely be used directly.
+    pub fn new<I: Into<Interval>>(iv: I, rvline: RVLine, line_count: usize, vline: L) -> Self {
         Self {
             interval: iv.into(),
             line_count,