page up / down on text

src/text.rs

@@ -3,19 +3,65 @@ use ui::{Action, Key, View};
 pub struct TextView {
     url: String,
     raw: String,
+    scroll: usize, // offset
+    count: usize,  // # of lines
 }
 
 impl View for TextView {
     fn process_input(&mut self, c: Key) -> Action {
-        Action::Unknown
+        let jump = 15;
+        match c {
+            Key::Down => {
+                if self.scroll < self.count - 1 {
+                    self.scroll += 1;
+                    Action::Redraw
+                } else {
+                    Action::None
+                }
+            }
+            Key::Up => {
+                if self.scroll > 0 {
+                    self.scroll -= 1;
+                    Action::Redraw
+                } else {
+                    Action::None
+                }
+            }
+            Key::PageUp | Key::Char('-') => {
+                if self.scroll > 0 {
+                    self.scroll -= jump;
+                    if self.scroll <= 0 {
+                        self.scroll = 0;
+                    }
+                    Action::Redraw
+                } else {
+                    Action::None
+                }
+            }
+            Key::PageDown | Key::Char(' ') => {
+                if self.scroll < self.count - 1 - jump {
+                    self.scroll += jump;
+                    if self.scroll >= self.count {
+                        self.scroll = self.count - 1;
+                    }
+                    Action::Redraw
+                } else {
+                    Action::None
+                }
+            }
+            _ => Action::Unknown,
+        }
     }
 
     fn render(&self, width: u16, height: u16) -> String {
         let mut out = String::new();
         for (i, line) in self.raw.split_terminator('\n').enumerate() {
-            if i as u16 > height - 4 {
+            if i > (self.scroll + height as usize) - 2 {
                 break;
             }
+            if i < self.scroll {
+                continue;
+            }
             out.push_str(line);
             out.push('\n');
         }
@@ -25,6 +71,12 @@ impl View for TextView {
 
 impl TextView {
     pub fn from(url: String, response: String) -> TextView {
-        TextView { url, raw: response }
+        let count = response.split_terminator('\n').count();
+        TextView {
+            url,
+            raw: response,
+            scroll: 0,
+            count,
+        }
     }
 }