1 files changed, 42 insertions(+), 84 deletions(-)

M linetest/src/shell/ui/buffer.rs

@@ 10,17 10,26 @@ use std::io;
 use super::{COLOR_TITLE_BG, COLOR_TITLE_FG};
 use textwrap;
 
-
-pub fn span(line: &str, cols: u16) -> Vec<String> {
-    let wrapped_str = textwrap::fill(line, cols as usize);
-    let lines = wrapped_str
-        .lines()
-        .map(|line| { line.to_owned() })
-        .collect::<Vec<_>>();
-    
-    lines
+struct Span {
+    lines: Vec<String>,
 }
 
+impl Span {
+    pub fn new(buf: &str, cols: u16) -> Self {
+        let wrapped_str = textwrap::fill(buf, cols as usize);
+
+        let lines = wrapped_str
+            .lines()
+            .map(|line| { line.to_owned() })
+            .collect::<Vec<_>>();
+
+        Self { lines: lines }
+    }
+
+    pub fn line_iter(&self) -> impl Iterator<Item = &String> {
+        self.lines.iter().rev()
+    }
+}
 /// The `Buffer` stores a list of lines which need to be displayed 
 /// in a fixed-width context. Lines can be added to the buffer and
 /// then displayed at any arbitrary resolution later.


@@ 29,11 38,8 @@ pub struct Buffer {
     rows: u16,
 
     lines: Vec<String>,
-    
-    page_idx: usize,
-    curr_page: Vec<String>,
-    next_page: Vec<String>,
-    offset_lines: usize,
+    viewport_spans: Vec<Span>,
+    current_line_ptr: usize,
 
     needs_repaint: bool,
 }


@@ 45,12 51,8 @@ impl Buffer {
             rows: rows,
 
             lines: vec![],
-
-
-            curr_page: vec![],
-            next_page: vec![],
-            page_idx: 0,
-            offset_lines: 0,
+            viewport_spans: vec![],
+            current_line_ptr: 0,
 
             needs_repaint: true,
         }


@@ 67,47 69,18 @@ impl Buffer {
         self.needs_repaint = true;
     }
 
-    pub fn draw_page_n(&mut self, page_num: usize) -> Vec<String> {
-        self.lines
-            .iter()
-            .rev()
-            .flat_map(|line| { span(line, self.cols) })
-            .skip(self.rows as usize * page_num)
-            .take(self.rows as usize)
-            .collect::<Vec<_>>()
-    }
-
     pub fn scroll_up(&mut self) {
-        let offset_len = 3;
-        let new_offset = cmp::min(self.next_page.len(), self.offset_lines + offset_len);
-
-        if new_offset == self.rows as usize {
-            self.page_idx += 1;
-            self.offset_lines = 0;
-            self.needs_repaint = true;
-        } else if new_offset > self.rows as usize && self.next_page.len() > 0 {
-            // go to next page
-            self.page_idx += 1;
-            self.offset_lines = 0;
-            self.needs_repaint = true;
-        } else if new_offset > self.offset_lines {
-            self.offset_lines = new_offset;
+        if (self.current_line_ptr + 1) <= self.lines.len() {
+            self.current_line_ptr += 1;
             self.needs_repaint = true;
         }
     }
 
     pub fn scroll_down(&mut self) {
-        let offset_len = std::cmp::min(3, self.offset_lines);
-
-        if offset_len >= self.offset_lines && self.page_idx > 0 {
-            self.page_idx -= 1;
-            self.offset_lines = self.rows as usize - offset_len;
-            self.needs_repaint = true;
-        } else if offset_len > 0 {
-            self.offset_lines -= offset_len;
+        if self.current_line_ptr > 0 {
+            self.current_line_ptr -= 1;
             self.needs_repaint = true;
         }
-
     }
 
     /// The caller *must* set the cursor to the row where this buffer should be rendered.


@@ 117,48 90,33 @@ impl Buffer {
         if !self.needs_repaint { return Ok(()); }
         self.needs_repaint = false;
 
-        // draw the current neighboring pages
-        self.curr_page = self.draw_page_n(self.page_idx);
-        self.next_page = self.draw_page_n(self.page_idx + 1);
-
         // move to bottom-most row.
         stdout
         .queue(cursor::MoveDown(self.rows - 1))?
         .queue(cursor::MoveToColumn(0))?;
 
-        let mut rows_drawn = self.rows;
-
-        // draw (rows - offset) lines from front buffer
-        for line in self.curr_page.iter().skip(self.offset_lines) {
-            stdout
-            .queue(Clear(ClearType::CurrentLine))?
-            .queue(Print(line))?
-            .queue(cursor::MoveUp(1))?
-            .queue(cursor::MoveToColumn(0))?;
+        // resize the spans starting from current line
+        self.viewport_spans = self.lines
+        .iter()
+        .rev()
+        .skip(self.current_line_ptr)
+        .map(|line| Span::new(line, self.cols))
+        .collect::<Vec<_>>();
 
-            rows_drawn -= 1;
-        }
+        let viewport_lines = self.viewport_spans
+            .iter()
+            .flat_map(|span| span.line_iter())
+            .take(self.rows as usize);
 
-        // draw remaining (offset) lines from back buffer
-        for line in self.next_page.iter().take(self.offset_lines) {
+        for line in viewport_lines {
             stdout
-            .queue(Clear(ClearType::CurrentLine))?
-            .queue(Print(line))?
-            .queue(cursor::MoveUp(1))?
-            .queue(cursor::MoveToColumn(0))?;
-
-            rows_drawn -= 1;
+                .queue(Clear(ClearType::CurrentLine))?
+                .queue(Print(line))?
+                .queue(cursor::MoveUp(1))?
+                .queue(cursor::MoveToColumn(0))?;
         }
 
-        // clear rest of buffer ...
-        while rows_drawn > 0 {
-            stdout
-            .queue(Clear(ClearType::CurrentLine))?
-            .queue(cursor::MoveUp(1))?
-            .queue(cursor::MoveToColumn(0))?;
 
-            rows_drawn -= 1;
-        }
 
         // while rows_left > 0 {
         //     // grab the next buffer line