From 76fc52441fc8988cb1e93225f09b4c04893f1b94 Mon Sep 17 00:00:00 2001
From: ArthurSonzogni <sonzogniarthur@gmail.com>
Date: Sat, 2 May 2020 20:39:56 +0200
Subject: [PATCH] Implement "alternative screen".

Apply this option automatically for "fullscreen" screen. Keep it
disabled for the other modes.

This fixes issue:
https://github.com/GiuseppeCesarano/just-fast/issues/2
---
 .../ftxui/component/screen_interactive.hpp    |  6 ++++-
 src/ftxui/component/screen_interactive.cpp    | 25 ++++++++++++++-----
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/include/ftxui/component/screen_interactive.hpp b/include/ftxui/component/screen_interactive.hpp
index 7b9b75b..ce838f5 100644
--- a/include/ftxui/component/screen_interactive.hpp
+++ b/include/ftxui/component/screen_interactive.hpp
@@ -43,7 +43,11 @@ class ScreenInteractive : public Screen {
     TerminalOutput,
   };
   Dimension dimension_ = Dimension::Fixed;
-  ScreenInteractive(int dimx, int dimy, Dimension dimension);
+  bool use_alternative_screen_ = false;
+  ScreenInteractive(int dimx,
+                    int dimy,
+                    Dimension dimension,
+                    bool use_alternative_screen);
 
   Sender<Event> event_sender_;
   Receiver<Event> event_receiver_;
diff --git a/src/ftxui/component/screen_interactive.cpp b/src/ftxui/component/screen_interactive.cpp
index 7af68d3..91c3085 100644
--- a/src/ftxui/component/screen_interactive.cpp
+++ b/src/ftxui/component/screen_interactive.cpp
@@ -124,6 +124,9 @@ static const char* SHOW_CURSOR = "\x1B[?25h";
 static const char* DISABLE_LINE_WRAP = "\x1B[7l";
 static const char* ENABLE_LINE_WRAP = "\x1B[7h";
 
+static const char* USE_ALTERNATIVE_SCREEN = "\x1B[?1049h";
+static const char* USE_NORMAL_SCREEN = "\x1B[?1049l";
+
 using SignalHandler = void(int);
 std::stack<std::function<void()>> on_exit_functions;
 void OnExit(int signal) {
@@ -146,8 +149,13 @@ void OnResize(int /* signal */) {
   on_resize();
 }
 
-ScreenInteractive::ScreenInteractive(int dimx, int dimy, Dimension dimension)
-    : Screen(dimx, dimy), dimension_(dimension) {
+ScreenInteractive::ScreenInteractive(int dimx,
+                                     int dimy,
+                                     Dimension dimension,
+                                     bool use_alternative_screen)
+    : Screen(dimx, dimy),
+      dimension_(dimension),
+      use_alternative_screen_(use_alternative_screen) {
   event_receiver_ = MakeReceiver<Event>();
   event_sender_ = event_receiver_->MakeSender();
 }
@@ -156,22 +164,22 @@ ScreenInteractive::~ScreenInteractive() {}
 
 // static
 ScreenInteractive ScreenInteractive::FixedSize(int dimx, int dimy) {
-  return ScreenInteractive(dimx, dimy, Dimension::Fixed);
+  return ScreenInteractive(dimx, dimy, Dimension::Fixed, false);
 }
 
 // static
 ScreenInteractive ScreenInteractive::Fullscreen() {
-  return ScreenInteractive(0, 0, Dimension::Fullscreen);
+  return ScreenInteractive(0, 0, Dimension::Fullscreen, true);
 }
 
 // static
 ScreenInteractive ScreenInteractive::TerminalOutput() {
-  return ScreenInteractive(0, 0, Dimension::TerminalOutput);
+  return ScreenInteractive(0, 0, Dimension::TerminalOutput, false);
 }
 
 // static
 ScreenInteractive ScreenInteractive::FitComponent() {
-  return ScreenInteractive(0, 0, Dimension::FitComponent);
+  return ScreenInteractive(0, 0, Dimension::FitComponent, false);
 }
 
 void ScreenInteractive::PostEvent(Event event) {
@@ -257,6 +265,11 @@ void ScreenInteractive::Loop(Component* component) {
       std::thread(&UnixEventListener, &quit_, std::move(char_sender));
 #endif
 
+  if (use_alternative_screen_) {
+    std::cout << USE_ALTERNATIVE_SCREEN;
+    on_exit_functions.push([] { std::cout << USE_NORMAL_SCREEN; });
+  }
+
   // The main loop.
   while (!quit_) {
     std::cout << reset_cursor_position << ResetPosition();