From cc998af4d860a4549c9e03b7382b1553deee371f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Roblot?= <clement.roblot@martobre.fr>
Date: Mon, 2 Oct 2023 15:29:23 +0700
Subject: [PATCH] Scrollbar coloring (#755)

This a proposed MR to fix #754. While building the scroll bar the pixels were completely reseted thus canceling any style previously applied to said pixels. This MR removes this resetting of the pixels and leaves only the drawing of the shape of the scroll bar.
---
 src/ftxui/dom/scroll_indicator.cpp      |   2 -
 src/ftxui/dom/scroll_indicator_test.cpp | 103 ++++++++++++++++++++++++
 2 files changed, 103 insertions(+), 2 deletions(-)

diff --git a/src/ftxui/dom/scroll_indicator.cpp b/src/ftxui/dom/scroll_indicator.cpp
index 05480bb0..ec1386a0 100644
--- a/src/ftxui/dom/scroll_indicator.cpp
+++ b/src/ftxui/dom/scroll_indicator.cpp
@@ -64,7 +64,6 @@ Element vscroll_indicator(Element child) {
         const bool down = (start_y <= y_down) && (y_down <= start_y + size);
 
         const char* c = up ? (down ? "┃" : "╹") : (down ? "╻" : " ");  // NOLINT
-        screen.PixelAt(x, y) = Pixel();
         screen.PixelAt(x, y).character = c;
       }
     }
@@ -121,7 +120,6 @@ Element hscroll_indicator(Element child) {
 
         const char* c =
             left ? (right ? "─" : "╴") : (right ? "╶" : " ");  // NOLINT
-        screen.PixelAt(x, y) = Pixel();
         screen.PixelAt(x, y).character = c;
       }
     }
diff --git a/src/ftxui/dom/scroll_indicator_test.cpp b/src/ftxui/dom/scroll_indicator_test.cpp
index 3b104b19..7dbd4c0a 100644
--- a/src/ftxui/dom/scroll_indicator_test.cpp
+++ b/src/ftxui/dom/scroll_indicator_test.cpp
@@ -9,6 +9,7 @@
 #include "ftxui/dom/elements.hpp"  // for operator|, Element, operator|=, text, vbox, Elements, border, focus, frame, vscroll_indicator
 #include "ftxui/dom/node.hpp"      // for Render
 #include "ftxui/screen/screen.hpp"  // for Screen
+#include "ftxui/screen/color.hpp"   // for Color, Color::Red
 
 // NOLINTBEGIN
 namespace ftxui {
@@ -127,6 +128,60 @@ TEST(ScrollIndicator, BasicVertical) {
             "╰────╯");
 }
 
+TEST(ScrollIndicator, VerticalColorable) {
+
+  // The list we generate looks like this
+  //           "╭────╮\r\n"
+  //           "│0  ┃│\r\n"
+  //           "│1  ┃│\r\n"
+  //           "│2   │\r\n"
+  //           "│3   │\r\n"
+  //           "╰────╯"
+
+  auto element = MakeVerticalList(0, 10) | color(Color::Red);
+  Screen screen(6, 6);
+  Render(screen, element);
+
+  EXPECT_EQ(screen.PixelAt(4, 4).foreground_color, Color::Red);
+  EXPECT_EQ(screen.PixelAt(4, 4).background_color, Color());
+}
+
+TEST(ScrollIndicator, VerticalBackgroundColorable) {
+
+  // The list we generate looks like this
+  //           "╭────╮\r\n"
+  //           "│0  ┃│\r\n"
+  //           "│1  ┃│\r\n"
+  //           "│2   │\r\n"
+  //           "│3   │\r\n"
+  //           "╰────╯"
+
+  auto element = MakeVerticalList(0, 10) | bgcolor(Color::Red);
+  Screen screen(6, 6);
+  Render(screen, element);
+
+  EXPECT_EQ(screen.PixelAt(4, 4).foreground_color, Color());
+  EXPECT_EQ(screen.PixelAt(4, 4).background_color, Color::Red);
+}
+
+TEST(ScrollIndicator, VerticalFullColorable) {
+
+  // The list we generate looks like this
+  //           "╭────╮\r\n"
+  //           "│0  ┃│\r\n"
+  //           "│1  ┃│\r\n"
+  //           "│2   │\r\n"
+  //           "│3   │\r\n"
+  //           "╰────╯"
+
+  auto element = MakeVerticalList(0, 10) | color(Color::Red) | bgcolor(Color::Red);
+  Screen screen(6, 6);
+  Render(screen, element);
+
+  EXPECT_EQ(screen.PixelAt(4, 4).foreground_color, Color::Red);
+  EXPECT_EQ(screen.PixelAt(4, 4).background_color, Color::Red);
+}
+
 TEST(ScrollIndicator, BasicHorizontal) {
   EXPECT_EQ(PrintHorizontalList(0, 10),
             "╭────╮\r\n"
@@ -177,6 +232,54 @@ TEST(ScrollIndicator, BasicHorizontal) {
             "╰────╯");
 }
 
+TEST(ScrollIndicator, HorizontalColorable) {
+
+  // The list we generate looks like this
+  //           "╭────╮\r\n"
+  //           "│5678│\r\n"
+  //           "│  ──│\r\n"
+  //           "╰────╯"
+
+  auto element = MakeHorizontalList(6, 10) | color(Color::Red);
+  Screen screen(6, 4);
+  Render(screen, element);
+
+  EXPECT_EQ(screen.PixelAt(4, 2).foreground_color, Color::Red);
+  EXPECT_EQ(screen.PixelAt(4, 2).background_color, Color());
+}
+
+TEST(ScrollIndicator, HorizontalBackgroundColorable) {
+
+  // The list we generate looks like this
+  //           "╭────╮\r\n"
+  //           "│5678│\r\n"
+  //           "│  ──│\r\n"
+  //           "╰────╯"
+
+  auto element = MakeHorizontalList(6, 10) | bgcolor(Color::Red);
+  Screen screen(6, 4);
+  Render(screen, element);
+
+  EXPECT_EQ(screen.PixelAt(4, 2).foreground_color, Color());
+  EXPECT_EQ(screen.PixelAt(4, 2).background_color, Color::Red);
+}
+
+TEST(ScrollIndicator, HorizontalFullColorable) {
+
+  // The list we generate looks like this
+  //           "╭────╮\r\n"
+  //           "│5678│\r\n"
+  //           "│  ──│\r\n"
+  //           "╰────╯"
+
+  auto element = MakeHorizontalList(6, 10) | color(Color::Red) | bgcolor(Color::Red);
+  Screen screen(6, 4);
+  Render(screen, element);
+
+  EXPECT_EQ(screen.PixelAt(4, 2).foreground_color, Color::Red);
+  EXPECT_EQ(screen.PixelAt(4, 2).background_color, Color::Red);
+}
+
 namespace {
 
 Element MakeHorizontalFlexboxList(int n) {