From bded2dd7405719bc24385ab2516a07d7abc07696 Mon Sep 17 00:00:00 2001
From: Evgeny Khudoba <evgeny.khudoba@yandex.ru>
Date: Sat, 22 Feb 2025 19:29:52 +0700
Subject: [PATCH] Move `PrintBuffer` to use `RefCell`

---
 cursive-core/src/cursive_root.rs |  6 +++---
 cursive-core/src/cursive_run.rs  | 10 +++++-----
 cursive-core/src/printer.rs      | 24 ++++++++++--------------
 3 files changed, 18 insertions(+), 22 deletions(-)

diff --git a/cursive-core/src/cursive_root.rs b/cursive-core/src/cursive_root.rs
index 77e6b00a..baad0ab1 100644
--- a/cursive-core/src/cursive_root.rs
+++ b/cursive-core/src/cursive_root.rs
@@ -1,10 +1,10 @@
 use std::any::Any;
+use std::cell::RefCell;
 use std::num::NonZeroU32;
 #[cfg(feature = "toml")]
 use std::path::Path;
 
 use crossbeam_channel::{self, Receiver, Sender};
-use parking_lot::RwLock;
 
 use crate::{
     backend,
@@ -123,8 +123,8 @@ impl Cursive {
         self.root.layout(size);
     }
 
-    pub(crate) fn draw(&mut self, buffer: &RwLock<crate::buffer::PrintBuffer>) {
-        let size = buffer.read().size();
+    pub(crate) fn draw(&mut self, buffer: &RefCell<crate::buffer::PrintBuffer>) {
+        let size = buffer.borrow().size();
 
         let printer = Printer::new(size, &self.theme, buffer);
 
diff --git a/cursive-core/src/cursive_run.rs b/cursive-core/src/cursive_run.rs
index 1a3b27fb..b3493a44 100644
--- a/cursive-core/src/cursive_run.rs
+++ b/cursive-core/src/cursive_run.rs
@@ -1,6 +1,6 @@
 use crate::{backend, buffer, event, Cursive, Vec2};
-use parking_lot::RwLock;
 use std::borrow::{Borrow, BorrowMut};
+use std::cell::RefCell;
 use std::time::Duration;
 
 // How long we wait between two empty input polls
@@ -16,7 +16,7 @@ pub struct CursiveRunner<C> {
     siv: C,
 
     backend: Box<dyn backend::Backend>,
-    buffer: RwLock<buffer::PrintBuffer>,
+    buffer: RefCell<buffer::PrintBuffer>,
 
     boring_frame_count: u32,
     // Last layer sizes of the stack view.
@@ -50,7 +50,7 @@ impl<C> CursiveRunner<C> {
         CursiveRunner {
             siv,
             backend,
-            buffer: RwLock::new(buffer::PrintBuffer::new()),
+            buffer: RefCell::new(buffer::PrintBuffer::new()),
             boring_frame_count: 0,
             last_sizes: Vec::new(),
         }
@@ -93,9 +93,9 @@ where
             self.last_sizes = sizes;
         }
 
-        self.buffer.write().resize(self.screen_size());
+        self.buffer.borrow_mut().resize(self.screen_size());
         self.siv.borrow_mut().draw(&self.buffer);
-        self.buffer.write().flush(&*self.backend);
+        self.buffer.borrow_mut().flush(&*self.backend);
     }
 
     /// Performs the first half of `Self::step()`.
diff --git a/cursive-core/src/printer.rs b/cursive-core/src/printer.rs
index 6378fb53..976fbe03 100644
--- a/cursive-core/src/printer.rs
+++ b/cursive-core/src/printer.rs
@@ -14,8 +14,7 @@ use crate::with::With;
 use crate::Vec2;
 
 use enumset::EnumSet;
-use parking_lot::RwLock;
-use std::cell::Cell;
+use std::cell::{Cell, RefCell};
 use std::cmp::min;
 use unicode_segmentation::UnicodeSegmentation;
 use unicode_width::UnicodeWidthStr;
@@ -70,7 +69,7 @@ pub struct Printer<'a, 'b> {
     current_style: Cell<ConcreteStyle>,
 
     /// Backend used to actually draw things
-    buffer: &'b RwLock<PrintBuffer>,
+    buffer: &'b RefCell<PrintBuffer>,
 }
 
 impl<'a, 'b> Printer<'a, 'b> {
@@ -78,7 +77,7 @@ impl<'a, 'b> Printer<'a, 'b> {
     ///
     /// But nobody needs to know that.
     #[doc(hidden)]
-    pub fn new<T: Into<Vec2>>(size: T, theme: &'a Theme, buffer: &'b RwLock<PrintBuffer>) -> Self {
+    pub fn new<T: Into<Vec2>>(size: T, theme: &'a Theme, buffer: &'b RefCell<PrintBuffer>) -> Self {
         let size = size.into();
         Printer {
             offset: Vec2::zero(),
@@ -105,7 +104,7 @@ impl<'a, 'b> Printer<'a, 'b> {
     ///
     /// This is the size of the entire terminal, not just the area this printer can write into.
     pub fn buffer_size(&self) -> Vec2 {
-        self.buffer.read().size()
+        self.buffer.borrow().size()
     }
 
     /// Clear the screen.
@@ -115,7 +114,7 @@ impl<'a, 'b> Printer<'a, 'b> {
     /// Users rarely need to call this directly.
     pub fn clear(&self) {
         let color = self.theme.palette[PaletteColor::Background];
-        self.buffer.write().fill(
+        self.buffer.borrow_mut().fill(
             " ",
             ColorPair {
                 front: color,
@@ -258,7 +257,7 @@ impl<'a, 'b> Printer<'a, 'b> {
 
         let start = start + self.offset;
         self.buffer
-            .write()
+            .borrow_mut()
             .print_at(start, text, self.current_style());
     }
 
@@ -294,7 +293,7 @@ impl<'a, 'b> Printer<'a, 'b> {
         let start = start + self.offset;
         for y in 0..height {
             self.buffer
-                .write()
+                .borrow_mut()
                 .print_at(start + (0, y), c, self.current_style());
         }
     }
@@ -304,7 +303,7 @@ impl<'a, 'b> Printer<'a, 'b> {
     where
         F: FnOnce(&mut Window<'_>) -> R,
     {
-        let mut buffer = self.buffer.write();
+        let mut buffer = self.buffer.borrow_mut();
         let mut window = buffer
             .window(self.output_window())
             .expect("printer size exceeds backend size");
@@ -362,7 +361,7 @@ impl<'a, 'b> Printer<'a, 'b> {
         let repetitions = min(width, self.output_size.x - start.x) / c_width;
 
         let mut start = start + self.offset;
-        let mut buffer = self.buffer.write();
+        let mut buffer = self.buffer.borrow_mut();
         let style = self.current_style();
         for _ in 0..repetitions {
             buffer.print_at(start, c, style);
@@ -424,10 +423,7 @@ impl<'a, 'b> Printer<'a, 'b> {
     /// that will apply the given color on prints.
     ///
     /// Does not change the current set of active effects (bold/underline/...).
-    pub fn with_color<F>(&self, c: ColorStyle, f: F)
-    where
-        F: FnOnce(&Printer),
-    {
+    pub fn with_color<F: FnOnce(&Printer)>(&self, c: ColorStyle, f: F) {
         let sub = self.clone().with(|sub| sub.set_color(c));
 
         f(&sub);