Implement faux scrolling

This patch implements faux scrolling inside the alternate screen buffer.

Whenever the user scrolls up or down while the alternate screen buffer
is active, instead of actual scrolling three up/down arrow keys are
inserted.

1 files changed, 32 insertions, 9 deletions

diff --git a/src/input.rs b/src/input.rs
index 4901a409..8f6048f0 100644
--- a/src/input.rs
+++ b/src/input.rs
@@ -365,7 +365,7 @@ impl<'a, A: ActionContext + 'a> Processor<'a, A> {
     }
 
     pub fn on_mouse_wheel(&mut self, delta: MouseScrollDelta, phase: TouchPhase) {
-        let modes = mode::MOUSE_REPORT_CLICK | mode::MOUSE_MOTION | mode::SGR_MOUSE;
+        let modes = mode::MOUSE_REPORT_CLICK | mode::MOUSE_MOTION | mode::SGR_MOUSE | mode::ALT_SCREEN_BUF;
         if !self.ctx.terminal_mode().intersects(modes) {
             return;
         }
@@ -374,6 +374,18 @@ impl<'a, A: ActionContext + 'a> Processor<'a, A> {
             MouseScrollDelta::LineDelta(_columns, lines) => {
                 let to_scroll = self.ctx.mouse_mut().lines_scrolled + lines;
 
+                // Faux scrolling
+                if self.ctx.terminal_mode().intersects(mode::ALT_SCREEN_BUF) {
+                    if to_scroll > 0. {
+                        // Scroll up three lines
+                        self.ctx.write_to_pty("\x1bOA\x1bOA\x1bOA".as_bytes());
+                    } else {
+                        // Scroll down three lines
+                        self.ctx.write_to_pty("\x1bOB\x1bOB\x1bOB".as_bytes());
+                    }
+                    return;
+                }
+
                 let code = if to_scroll > 0.0 {
                     64
                 } else {
@@ -396,15 +408,26 @@ impl<'a, A: ActionContext + 'a> Processor<'a, A> {
                         let height = self.ctx.size_info().cell_height as i32;
 
                         while self.ctx.mouse_mut().scroll_px.abs() >= height {
-                            let button = if self.ctx.mouse_mut().scroll_px > 0 {
-                                self.ctx.mouse_mut().scroll_px -= height;
-                                64
+                            if self.ctx.terminal_mode().intersects(mode::ALT_SCREEN_BUF) {
+                                // Faux scrolling
+                                if self.ctx.mouse_mut().scroll_px > 0 {
+                                    // Scroll up three lines
+                                    self.ctx.write_to_pty("\x1bOA\x1bOA\x1bOA".as_bytes());
+                                } else {
+                                    // Scroll down three lines
+                                    self.ctx.write_to_pty("\x1bOB\x1bOB\x1bOB".as_bytes());
+                                }
                             } else {
-                                self.ctx.mouse_mut().scroll_px += height;
-                                65
-                            };
-
-                            self.normal_mouse_report(button);
+                                let button = if self.ctx.mouse_mut().scroll_px > 0 {
+                                    self.ctx.mouse_mut().scroll_px -= height;
+                                    64
+                                } else {
+                                    self.ctx.mouse_mut().scroll_px += height;
+                                    65
+                                };
+
+                                self.normal_mouse_report(button);
+                            }
                         }
                     },
                     _ => (),