Add Page Up and Page Down

rust/core-lib/src/edit_types.rs

@@ -48,6 +48,7 @@ pub(crate) enum ViewEvent {
     SelectionForReplace,
     SelectionIntoLines,
     CollapseSelections,
+    PageUpDown(Movement),
 }
 
 /// Events that modify the buffer
@@ -264,6 +265,8 @@ impl From<EditNotification> for EventDomain {
             PlayRecording { recording_name } => SpecialEvent::PlayRecording(recording_name).into(),
             ClearRecording { recording_name } => SpecialEvent::ClearRecording(recording_name).into(),
             CollapseSelections => ViewEvent::CollapseSelections.into(),
+            PageUp => ViewEvent::PageUpDown(Movement::UpPage).into(),
+            PageDown => ViewEvent::PageUpDown(Movement::DownPage).into(),
         }
     }
 }

rust/core-lib/src/rpc.rs

@@ -510,6 +510,8 @@ pub enum EditNotification {
         recording_name: String,
     },
     CollapseSelections,
+    PageUp,
+    PageDown,
 }
 
 /// The edit related requests.

rust/core-lib/src/view.rs

@@ -267,6 +267,7 @@ impl View {
             Replace { chars, preserve_case } => self.do_set_replace(chars, preserve_case),
             SelectionForReplace => self.do_selection_for_replace(text),
             SelectionIntoLines => self.do_split_selection_into_lines(text),
+            PageUpDown(movement) => self.page_up_down(movement, text),
         }
     }
 
@@ -322,6 +323,25 @@ impl View {
         self.scroll_to = Some(end);
     }
 
+    pub fn page_up_down(&mut self, movement: Movement, text: &Rope) {
+        let nm = self.first_line as usize;
+        let op = self.scroll_height() as usize;
+
+        let newPos = self.offset_of_line(text, nm + 2 * op);
+
+        let end = newPos;
+        let line = self.line_of_offset(text, end);
+        if line < self.first_line {
+            self.first_line = line;
+        } else if self.first_line + self.height <= line {
+            self.first_line = line - (self.height - 1);
+        }
+
+        let offset = self.sel_regions().last().unwrap().end;
+
+        self.scroll_to = Some(end);
+    }
+
     /// Toggles a caret at the given offset.
     pub fn toggle_sel(&mut self, text: &Rope, offset: usize) {
         // We could probably reduce the cloning of selections by being clever.