scrolling and following proc output

src/preview.rs

@@ -406,7 +406,9 @@ impl Previewer {
             let mut textview = TextView {
                 lines: output.lines().map(|s| s.to_string()).collect(),
                 buffer: String::new(),
-                core: core.clone()};
+                core: core.clone(),
+                follow: false,
+                offset: 0};
             textview.set_coordinates(&core.coordinates).log();
             textview.refresh().log();
             textview.animate_slide_up().log();

src/proclist.rs

@@ -261,6 +261,41 @@ impl ProcView {
         self.viewing = Some(self.get_listview().get_selection());
         Ok(())
     }
+
+    pub fn toggle_follow(&mut self) -> HResult<()> {
+        self.get_textview().widget()?.lock()?.as_mut()?.toggle_follow();
+        Ok(())
+    }
+
+    pub fn scroll_up(&mut self) -> HResult<()> {
+        self.get_textview().widget()?.lock()?.as_mut()?.scroll_up();
+        Ok(())
+    }
+
+    pub fn scroll_down(&mut self) -> HResult<()> {
+        self.get_textview().widget()?.lock()?.as_mut()?.scroll_down();
+        Ok(())
+    }
+
+    pub fn page_up(&mut self) -> HResult<()> {
+        self.get_textview().widget()?.lock()?.as_mut()?.page_up();
+        Ok(())
+    }
+
+    pub fn page_down(&mut self) -> HResult<()> {
+        self.get_textview().widget()?.lock()?.as_mut()?.page_down();
+        Ok(())
+    }
+
+    pub fn scroll_top(&mut self) -> HResult<()> {
+        self.get_textview().widget()?.lock()?.as_mut()?.scroll_top();
+        Ok(())
+    }
+
+    pub fn scroll_bottom(&mut self) -> HResult<()> {
+        self.get_textview().widget()?.lock()?.as_mut()?.scroll_bottom();
+        Ok(())
+    }
 }
 
 impl Widget for ProcView {
@@ -293,6 +328,13 @@ impl Widget for ProcView {
             Key::Down | Key::Char('n') => {
                 self.get_listview().move_down();
             }
+            Key::Char('f') => { self.toggle_follow().log(); }
+            Key::Ctrl('n') => { self.scroll_down().log(); },
+            Key::Ctrl('p') => { self.scroll_up().log(); },
+            Key::Ctrl('v') => { self.page_down().log(); },
+            Key::Alt('v') => { self.page_up().log(); },
+            Key::Char('>') => { self.scroll_bottom().log(); },
+            Key::Char('<') => { self.scroll_top().log(); }
             _ => {}
         }
         self.refresh().log();

src/textview.rs

@@ -9,7 +9,9 @@ use crate::fail::HResult;
 pub struct TextView {
     pub lines: Vec<String>,
     pub buffer: String,
-    pub core: WidgetCore
+    pub core: WidgetCore,
+    pub follow: bool,
+    pub offset: usize,
 }
 
 impl TextView {
@@ -17,7 +19,9 @@ impl TextView {
         TextView {
             lines: vec![],
             buffer: String::new(),
-            core: core.clone()
+            core: core.clone(),
+            follow: false,
+            offset: 0,
         }
     }
     pub fn new_from_file(core: &WidgetCore, file: &File) -> HResult<TextView> {
@@ -32,7 +36,9 @@ impl TextView {
         Ok(TextView {
             lines: lines,
             buffer: String::new(),
-            core: core.clone()
+            core: core.clone(),
+            follow: false,
+            offset: 0,
         })
     }
     pub fn new_from_file_limit_lines(core: &WidgetCore,
@@ -51,7 +57,9 @@ impl TextView {
         Ok(TextView {
             lines: lines,
             buffer: String::new(),
-            core: core.clone()
+            core: core.clone(),
+            follow: false,
+            offset: 0,
         })
     }
 
@@ -60,6 +68,60 @@ impl TextView {
         self.lines = lines;
         self.refresh()
     }
+
+    pub fn toggle_follow(&mut self) {
+        self.follow = !self.follow
+    }
+
+    pub fn scroll(&mut self, amount: isize) {
+        let ysize = self.get_coordinates().unwrap().ysize() as isize;
+        let offset = self.offset as isize;
+        let len = self.lines.len() as isize;
+
+        if len <= ysize + offset { return }
+
+        if amount > 0 {
+            if  ysize + amount + offset + 1 >= len {
+                // Too far down
+                self.offset = (len - ysize - 1) as usize;
+            } else {
+                self.offset = (offset as isize + amount) as usize;
+            }
+        } else if amount < 0 {
+            if offset + amount >= 0 {
+                self.offset = (offset + amount) as usize;
+            } else {
+                self.offset = 0;
+            }
+        }
+    }
+
+    pub fn scroll_up(&mut self) {
+        self.scroll(-1);
+    }
+
+    pub fn scroll_down(&mut self) {
+        self.scroll(1);
+    }
+
+    pub fn page_up(&mut self) {
+        let ysize = self.get_coordinates().unwrap().ysize() as isize;
+        self.scroll(0 - ysize + 1);
+    }
+
+    pub fn page_down(&mut self) {
+        let ysize = self.get_coordinates().unwrap().ysize() as isize;
+        self.scroll(ysize - 1);
+    }
+
+    pub fn scroll_top(&mut self) {
+        self.offset = 0;
+    }
+
+    pub fn scroll_bottom(&mut self) {
+        let len = self.lines.len() as isize;
+        self.scroll(len);
+    }
 }
 
 impl Widget for TextView {
@@ -72,11 +134,18 @@ impl Widget for TextView {
     fn refresh(&mut self) -> HResult<()> {
         let (xsize, ysize) = self.get_coordinates()?.size().size();
         let (xpos, ypos) = self.get_coordinates()?.position().position();
+        let len = self.lines.len();
+
+        if self.follow {
+            self.scroll_bottom();
+        }
+
 
         self.buffer = self.get_clearlist()? +
             &self
             .lines
             .iter()
+            .skip(self.offset)
             .take(ysize as usize)
             .enumerate()
             .map(|(i, line)| {