From b6aaf829b86d8b8ab443510c8ff815677dd419eb Mon Sep 17 00:00:00 2001
From: Wez Furlong <wez@wezfurlong.org>
Date: Sat, 21 Jul 2018 14:57:24 -0700
Subject: [PATCH] add ClearToEndOfScreen operation

---
 src/render/terminfo.rs | 24 ++++++++++++++++++++++++
 src/render/windows.rs  | 30 ++++++++++++++++++++++++++++++
 src/screen.rs          | 37 ++++++++++++++++++++++++++++++++++++-
 3 files changed, 90 insertions(+), 1 deletion(-)

diff --git a/src/render/terminfo.rs b/src/render/terminfo.rs
index 8250f81d1..6760164a5 100644
--- a/src/render/terminfo.rs
+++ b/src/render/terminfo.rs
@@ -331,6 +331,30 @@ impl TerminfoRenderer {
                         )?;
                     }
                 }
+                Change::ClearToEndOfScreen(color) => {
+                    // ClearScreen implicitly resets all to default
+                    let defaults = CellAttributes::default()
+                        .set_background(color.clone())
+                        .clone();
+                    if self.current_attr != defaults {
+                        self.pending_attr = Some(defaults);
+                        self.flush_pending_attr(out)?;
+                    }
+                    self.pending_attr = None;
+
+                    // FIXME: this doesn't behave correctly for terminals without bce.
+                    // If we knew the current cursor position, we would be able to
+                    // emit the correctly colored background for that case.
+                    if let Some(clr) = self.get_capability::<cap::ClrEos>() {
+                        clr.expand().to(out.by_ref())?;
+                    } else {
+                        write!(
+                            out,
+                            "{}",
+                            CSI::Edit(Edit::EraseInDisplay(EraseInDisplay::EraseToEndOfDisplay))
+                        )?;
+                    }
+                }
                 Change::Attribute(AttributeChange::Intensity(value)) => {
                     record!(set_intensity, value);
                 }
diff --git a/src/render/windows.rs b/src/render/windows.rs
index 9ff511074..063e84bd6 100644
--- a/src/render/windows.rs
+++ b/src/render/windows.rs
@@ -170,6 +170,36 @@ impl WindowsConsoleRenderer {
                         width,
                     )?;
                 }
+                Change::ClearToEndOfScreen(color) => {
+                    out.flush()?;
+                    self.current_attr = CellAttributes::default()
+                        .set_background(color.clone())
+                        .clone();
+
+                    let info = out.get_buffer_info()?;
+                    let width =
+                        (info.dwSize.X as u32).saturating_sub(info.dwCursorPosition.X as u32);
+                    out.fill_char(' ', info.dwCursorPosition.X, info.dwCursorPosition.Y, width)?;
+                    out.fill_attr(
+                        to_attr_word(&self.current_attr),
+                        info.dwCursorPosition.X,
+                        info.dwCursorPosition.Y,
+                        width,
+                    )?;
+                    // Clear the full width of the buffer (not the viewport size)
+                    let visible_width = info.dwSize.X as u32;
+                    // And clear all of the visible lines below the cursor
+                    let visible_height =
+                        (info.dwSize.Y as u32).saturating_sub((info.dwCursorPosition.Y as u32) + 1);
+                    let num_spaces = visible_width * visible_height;
+                    out.fill_char(' ', 0, info.dwCursorPosition.Y + 1, num_spaces as u32)?;
+                    out.fill_attr(
+                        to_attr_word(&self.current_attr),
+                        0,
+                        info.dwCursorPosition.Y + 1,
+                        num_spaces as u32,
+                    )?;
+                }
                 Change::Text(text) => {
                     out.flush()?;
                     out.set_attr(to_attr_word(&self.current_attr))?;
diff --git a/src/screen.rs b/src/screen.rs
index 398cad086..c7bab6c6b 100644
--- a/src/screen.rs
+++ b/src/screen.rs
@@ -44,7 +44,12 @@ pub enum Change {
     /// edge of the screen.  The background color is set to the
     /// provided color.  The cursor position remains unchanged.
     ClearToEndOfLine(ColorAttribute),
-    //   ClearToEndOfScreen,
+    /// Clear from the current cursor X position to the rightmost
+    /// edge of the screen on the current line.  Clear all of the
+    /// lines below the current cursor Y position.  The background
+    /// color is set ot the provided color.  The cursor position
+    /// remains unchanged.
+    ClearToEndOfScreen(ColorAttribute),
     /// Move the cursor to the specified `Position`.
     CursorPosition { x: Position, y: Position },
     /*   CursorVisibility(bool),
@@ -250,6 +255,7 @@ impl Screen {
             Change::CursorPosition { x, y } => self.set_cursor_pos(x, y),
             Change::ClearScreen(color) => self.clear_screen(color),
             Change::ClearToEndOfLine(color) => self.clear_eol(color),
+            Change::ClearToEndOfScreen(color) => self.clear_eos(color),
         }
     }
 
@@ -265,6 +271,21 @@ impl Screen {
         }
     }
 
+    fn clear_eos(&mut self, color: &ColorAttribute) {
+        self.attributes = CellAttributes::default()
+            .set_background(color.clone())
+            .clone();
+        let cleared = Cell::new(' ', self.attributes.clone());
+        for cell in self.lines[self.ypos].cells.iter_mut().skip(self.xpos) {
+            *cell = cleared.clone();
+        }
+        for line in &mut self.lines.iter_mut().skip(self.ypos + 1) {
+            for cell in &mut line.cells {
+                *cell = cleared.clone();
+            }
+        }
+    }
+
     fn clear_eol(&mut self, color: &ColorAttribute) {
         self.attributes = CellAttributes::default()
             .set_background(color.clone())
@@ -758,6 +779,20 @@ mod test {
         assert_eq!(s.screen_chars_to_string(), "   \nw  \nfoo\n");
     }
 
+    #[test]
+    fn clear_eos() {
+        let mut s = Screen::new(3, 3);
+        s.add_change("helwowfoo");
+        s.add_change(Change::ClearToEndOfScreen(Default::default()));
+        assert_eq!(s.screen_chars_to_string(), "hel\nwow\nfoo\n");
+        s.add_change(Change::CursorPosition {
+            x: Position::Absolute(1),
+            y: Position::Absolute(1),
+        });
+        s.add_change(Change::ClearToEndOfScreen(Default::default()));
+        assert_eq!(s.screen_chars_to_string(), "hel\nw  \n   \n");
+    }
+
     #[test]
     fn cursor_movement() {
         let mut s = Screen::new(4, 3);