fix scroll

src/app/rendering/terminal_text/mod.rs

@@ -16,6 +16,7 @@ pub struct TerminalText {
     renderer: TextRenderer,
     dirty_regions: Vec<TextBounds>,
     cursor: Cursor,
+    max_scroll_lines: usize,
 }
 
 // TODO
@@ -66,12 +67,13 @@ impl TerminalText {
                 index: 0,
                 affinity: glyphon::Affinity::After,
             },
+            max_scroll_lines: 100,
         }
     }
 
-    fn get_line_bounds(&self, line: usize) -> TextBounds {
-        // Calculate the bounds for a specific line
-        if line >= self.buffer.lines.len() {
+    // Calculate the bounds delimited by the `start` and `end` lines
+    fn get_text_bounds(&self, start: usize, end: usize) -> TextBounds {
+        if start >= self.buffer.lines.len() || end > self.buffer.lines.len() {
             // Return default bounds for invalid line
             return TextBounds {
                 left: 0,
@@ -84,25 +86,24 @@ impl TerminalText {
         let line_height = self.buffer.metrics().line_height;
         let viewport_width = self.viewport.resolution().width;
 
-        // Use layout_runs to get information about wrapped lines
         let layout_iter = self.buffer.layout_runs();
         let mut top_line = 0;
         let mut bottom_line = 0;
-        let mut found_line = false;
 
-        // Iterate through layout runs to find our target line
+        let mut found_start_line = false;
+        let mut found_end_line = false;
+
         for (visual_line_count, run) in layout_iter.enumerate() {
-            if run.line_i == line {
-                // This run belongs to our target line
-                if !found_line {
-                    // First run of our target line
-                    top_line = visual_line_count;
-                    found_line = true;
+            if run.line_i == start && !found_start_line {
+                top_line = visual_line_count;
+                found_start_line = true;
+            }
+            if run.line_i == end {
+                if !found_end_line {
+                    found_end_line = true;
                 }
-                // Update bottom line for each run we find for this line
                 bottom_line = visual_line_count + 1;
-            } else if found_line {
-                // We've processed all runs for our target line
+            } else if found_end_line {
                 break;
             }
         }
@@ -150,14 +151,7 @@ impl TerminalText {
         }
 
         // Add 1 to include partially visible lines at the bottom
-        let end_line = if self.buffer.lines.is_empty() {
-            0
-        } else {
-            // Make sure we include at least the last logical line that has content in the viewport
-            trace!("Last logical line: {last_logical_line}");
-            trace!("Number of lines: {}", self.buffer.lines.len());
-            (last_logical_line + 1).min(self.buffer.lines.len())
-        };
+        let end_line = last_logical_line;
 
         trace!("visible line range goes from {start_line} to {end_line}");
 
@@ -166,9 +160,8 @@ impl TerminalText {
 
     fn ensure_visible_text_rendered(&mut self) {
         let (start_line, end_line) = self.get_visible_line_range();
-        for i in start_line..end_line {
-            self.dirty_regions.push(self.get_line_bounds(i));
-        }
+        self.dirty_regions
+            .push(self.get_text_bounds(start_line, end_line));
     }
 
     fn merge_dirty_regions(&self) -> TextBounds {
@@ -239,6 +232,14 @@ impl TerminalText {
         F: FnOnce(&mut Self) -> R,
     {
         let result = operation(self);
+
+        let mut scroll = self.buffer.scroll();
+        if self.buffer.lines.len() > self.max_scroll_lines {
+            self.buffer.lines.remove(0);
+            self.cursor.line -= 1;
+        }
+        scroll.line = self.buffer.lines.len();
+        self.buffer.set_scroll(scroll);
         self.buffer.shape_until_scroll(&mut self.font_system, false);
         self.ensure_visible_text_rendered();
         result
@@ -309,26 +310,6 @@ impl TerminalText {
             this.cursor.index = 0;
             // Create a new line with text after cursor
             this.buffer.lines.insert(this.cursor.line, new_line);
-
-            // Only adjust scroll if cursor would be outside visible area
-            let mut scroll = this.buffer.scroll();
-            let current_scroll_line =
-                (scroll.vertical / this.buffer.metrics().line_height).floor() as usize;
-            let max_visible_lines =
-                (safe_casts::u32_to_f32_or_max(this.viewport.resolution().height)
-                    / this.buffer.metrics().line_height)
-                    .floor() as usize;
-
-            // Only scroll if cursor would be below visible area
-            if this.cursor.line >= current_scroll_line + max_visible_lines {
-                scroll.vertical =
-                    safe_casts::usize_to_f32_or_max(this.cursor.line - max_visible_lines + 1)
-                        * this.buffer.metrics().line_height;
-                trace!("adjusting scroll to keep cursor visible: {:?}", scroll);
-                this.buffer.set_scroll(scroll);
-            } else {
-                trace!("keeping current scroll: {:?}", scroll);
-            }
         })
     }
 
@@ -378,11 +359,6 @@ impl TerminalText {
                 ret = true;
             }
 
-            if line > this.buffer.lines.len() {
-                let mut scroll = this.buffer.scroll();
-                scroll.vertical -= 1.0 * this.buffer.metrics().line_height;
-                this.buffer.set_scroll(scroll);
-            }
             ret
         })
     }