Allow changing scrollback history size at runtime

Making use of the changes that have been introduced in #1234 and #1284,
this allows changing the size of the scrollback buffer at runtime.

This simply changes the size of the raw inner buffer making use of the
optimized mutation algorithms introduced in #1284. As a result,
shrinking the scrollback history size at runtime should be basically
free and growing will only introduce a performance cost when there are
no more buffered lines. However, as a result there will not be any
memory freed when shrinking the scrollback history size at runtime.

As discussed in #1234 a potential solution for this could be to truncate
the raw buffer whenever more than X lines are deleted, however this
issue should not be very significant PR and if a solution is desired a
separate issue/PR should be opened.

This fixes #1235.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/grid/mod.rs b/src/grid/mod.rs
index 97614d71..535f6cc6 100644
--- a/src/grid/mod.rs
+++ b/src/grid/mod.rs
@@ -155,6 +155,13 @@ impl<T: Copy + Clone> Grid<T> {
         self.line_to_offset(line) + self.display_offset
     }
 
+    /// Update the size of the scrollback history
+    pub fn update_history(&mut self, history_size: usize, template: &T)
+    {
+        self.raw.update_history(history_size, Row::new(self.cols, &template));
+        self.scroll_limit = min(self.scroll_limit, history_size);
+    }
+
     pub fn scroll_display(&mut self, scroll: Scroll) {
         match scroll {
             Scroll::Lines(count) => {