Address @robinlinden comments.

Improve the Bazel build. Attempt to fix previous errors recorded while
trying to publish ftxui in the Bazel Central Registry:
- https://github.com/bazelbuild/bazel-central-registry/pull/4485
- https://buildkite.com/bazel/bcr-presubmit/builds/13601#01968b61-f5b2-4d16-94d0-c87a03a1a23b

Test against "recent" platforms
-------------------------------

Previously, I got the error:
```
gcc: error: unrecognized command line option '-std-c++20'; did you mean '-std-c++2a'?
```
This was due to using old distribution like ubuntu 2004. Test against
newer platforms only to avoid GCC version<-9.x.y

Downgrade gtest version.
------------------------

I suspect this caused the Bazel Central Registry error:
```
file:///workdir/modules/googletest/1.15.2/MODULE.bazel:68:20: name 'use_repo_rule' is not defined
```
I hoped using a lower version will fix the issue.

Tag gtest as dev_dependency
---------------------------

Presumably, this should avoid dependants to fetch it?

Enable --features-layering_check
--------------------------------

Aka clang `-Wprivate-header`. Fix the encountered errors.

Use clang in the CI
-------------------

The CI was defining clang/gcc in the matrix, but was not using it. Fix
the bug.

.bazelrc

@@ -0,0 +1,2 @@
+build --features=layering_check
+build --enable_bzlmod

.bcr/presubmit.yml

@@ -1,14 +1,16 @@
-# Copyright 2025 Arthur Sonzogni. All rights reserved.
-# Use of this source code is governed by the MIT license that can be found in
-# the LICENSE file.
 matrix:
+  # Note that gcc 9 and earlier aren't supported due to using --std=c++2a
+  # instead of --std=c++20
   platform:
-  - centos7
-  - debian10
-  - ubuntu2004
+  - debian11
+  - ubuntu2204
   - macos
+  - macos-arm64
   - windows
-  bazel: [6.x, 7.x, 8.x]
+  bazel:
+  #- 6.x -> Build fails with bazel 6.x
+  - 7.x
+  - 8.x
 tasks:
   verify_targets:
     name: Build and test.

.github/workflows/build.yaml

@@ -14,25 +14,30 @@ on:
 jobs:
 
   test_bazel:
-    name: "Bazel, ${{ matrix.compiler }}, ${{ matrix.os }}"
+    name: "Bazel, ${{ matrix.cxx }}, ${{ matrix.os }}"
     strategy:
       fail-fast: false
       matrix:
         include:
           - os: ubuntu-latest
-            compiler: gcc
+            cxx: g++
+            cc: gcc
 
           - os: ubuntu-latest
-            compiler: llvm
+            cxx: clang++
+            cc: clang
 
           - os: macos-latest
-            compiler: llvm
+            cxx: g++
+            cc: gcc
 
           - os: macos-latest
-            compiler: gcc
+            cxx: clang++
+            cc: clang
 
           - os: windows-latest
-            compiler: cl
+            cxx: cl
+            cc: cl
 
     runs-on: ${{ matrix.os }}
     steps:
@@ -40,10 +45,16 @@ jobs:
         uses: actions/checkout@v3
 
       - name: "Build with Bazel"
+        env:
+          CC: ${{ matrix.cc }}
+          CXX: ${{ matrix.cxx }}
         run: bazel build ...
 
       - name: "Tests with Bazel"
-        run: bazel run tests
+        env:
+          CC: ${{ matrix.cc }}
+          CXX: ${{ matrix.cxx }}
+        run: bazel test --test_output=all ...
 
   test_cmake:
     name: "CMake, ${{ matrix.compiler }}, ${{ matrix.os }}"

.github/workflows/publish.yaml

@@ -1,32 +1,24 @@
 name: "Publish to Bazel Central Registry"
 
 on:
-  # On manual trigger:
+  # Manual kick-off (you type the tag)
   workflow_dispatch:
     inputs:
       tag_name:
+        description: "Tag to publish"
         required: true
         type: string
 
-  # Called from the release workflow:
-  workflow_call:
-    inputs:
-      tag_name:
-        required: true
-        type: string
-    secrets:
-      PUBLISH_TOKEN:
-        required: true
+permissions:
+  contents:     write
 
 jobs:
   publish:
     uses: bazel-contrib/publish-to-bcr/.github/workflows/publish.yaml@v0.0.4
     with:
-      tag_name: ${{ inputs.tag_name }}
+      tag_name: ${{ github.event.inputs.tag_name }}
       registry_fork: ArthurSonzogni/bazel-central-registry
-    permissions:
-      attestations: write
-      contents: write
-      id-token: write
+      attest: false
+
     secrets:
       publish_token: ${{ secrets.PUBLISH_TOKEN }}

.github/workflows/release.yaml

@@ -13,6 +13,8 @@ permissions:
   # Needed to mint attestations
   id-token: write
   attestations: write
+  # Needed to upload release assets
+  contents: write
 
 jobs:
   release:
@@ -90,39 +92,9 @@ jobs:
         run: >
           git archive --format=tar.gz -o source.tar.gz HEAD
 
-      - name: Generate source attestation
-        id: attest_source
-        uses: actions/attest-build-provenance@v2
-        with:
-          subject-path: source.tar.gz
-
-      - name: Write source.intoto.jsonl
-        run: 
-          jq --compact-output < "${{ steps.attest_source.outputs.bundle-path }}" \
-            > source.tar.gz.intoto.jsonl
-
       - name: "Upload source package"
         uses: shogo82148/actions-upload-release-asset@v1
         with:
           upload_url: ${{ needs.release.outputs.upload_url }}
           asset_path: source.tar.gz
           overwrite: true
-
-      - name: "Upload source attestation"
-        uses: shogo82148/actions-upload-release-asset@v1
-        with:
-          upload_url: ${{ needs.release.outputs.upload_url }}
-          asset_path: source.tar.gz.intoto.jsonl
-          overwrite: true
-
-  # Publish to Bazel Central Registry.
-  # This call the .github/workflows/publish.yaml workflow.
-  publish_to_bazel_central_registry:
-    name: "Publish to Bazel Central Registry"
-    needs: package_source
-    uses: ./.github/workflows/publish.yaml
-    with:
-      tag_name: ${{ github.ref }}
-    secrets:
-      PUBLISH_TOKEN: ${{ secrets.PUBLISH_TOKEN }}
-

BUILD.bazel

@@ -16,19 +16,16 @@ load(":bazel/ftxui.bzl", "cpp20")
 load(":bazel/ftxui.bzl", "windows_copts")
 load(":bazel/ftxui.bzl", "pthread_linkopts")
 
-package(default_visibility = ["//visibility:public"])
+# A meta target depending on all of the ftxui submodules.
+# Note that component depends on dom and screen, so ftxui is just an alias for 
+# component.
+# ┌component──┐
+# │┌dom──────┐│
+# ││┌screen─┐││
+# └┴┴───────┴┴┘
+alias(name = "ftxui", actual = ":component")
 
-# A meta target that depends on all the ftxui sub modules.
-alias(
-    name = "ftxui",
-    # Note that :component depends on :dom, which depends on :screen. Bazel
-    # doesn't really support "public" and "private" dependencies. They are all
-    # public. This is equivalent to depending on all the submodules.
-    actual = ":component",
-    visibility = ["//visibility:public"],
-)
-
-# ftxui:screen is a module that provides a screen buffer and color management
+# @ftxui:screen is a module that provides a screen buffer and color management
 # for terminal applications. A screen is a 2D array of cells, each cell can
 # contain a glyph, a color, and other attributes. The library also provides
 # functions to manipulate the screen.
@@ -60,7 +57,7 @@ ftxui_cc_library(
     ],
 )
 
-# ftxui:dom is a library that provides a way to create and manipulate a
+# @ftxui:dom is a library that provides a way to create and manipulate a
 # "document" that can be rendered to a screen. The document is a tree of nodes.
 # Nodes can be text, layouts, or various decorators. Users needs to compose
 # nodes to create a document. A document is responsive to the size of the
@@ -130,7 +127,7 @@ ftxui_cc_library(
     deps = [":screen"],
 )
 
-# ftxui:component is a library to create "dynamic" component renderering and
+# @ftxui:component is a library to create "dynamic" component renderering and
 # updating a ftxui::dom document on the screen. It is a higher level API than
 # ftxui:dom.
 #
@@ -167,6 +164,13 @@ ftxui_cc_library(
         "src/ftxui/component/terminal_input_parser.hpp",
         "src/ftxui/component/util.cpp",
         "src/ftxui/component/window.cpp",
+
+        # Private header from ftxui:dom.
+        "src/ftxui/dom/node_decorator.hpp",
+
+        # Private header from ftxui:screen.
+        "src/ftxui/screen/string_internal.hpp",
+        "src/ftxui/screen/util.hpp",
     ],
     hdrs = [
         "include/ftxui/component/animation.hpp",
@@ -182,7 +186,10 @@ ftxui_cc_library(
         "include/ftxui/component/task.hpp",
     ],
     linkopts = pthread_linkopts(),
-    deps = [":dom"],
+    deps = [
+        ":dom",
+        ":screen",
+    ],
 )
 
 # FTXUI's tests
@@ -205,7 +212,6 @@ cc_test(
         "src/ftxui/component/resizable_split_test.cpp",
         "src/ftxui/component/slider_test.cpp",
         "src/ftxui/component/terminal_input_parser_test.cpp",
-        "src/ftxui/component/terminal_input_parser_test_fuzzer.cpp",
         "src/ftxui/component/toggle_test.cpp",
         "src/ftxui/dom/blink_test.cpp",
         "src/ftxui/dom/bold_test.cpp",
@@ -233,6 +239,17 @@ cc_test(
         "src/ftxui/screen/string_test.cpp",
         "src/ftxui/util/ref_test.cpp",
 
+        # Private header from ftxui:screen for string_test.cpp.
+        "src/ftxui/screen/string_internal.hpp",
+
+        # Private header from ftxui::component for
+        # terminal_input_parser_test.cpp.
+        "src/ftxui/component/terminal_input_parser.hpp",
+
+        # Private header from ftxui::dom for
+        # flexbox_helper_test.cpp.
+        "src/ftxui/dom/flexbox_helper.hpp",
+
         # TODO: Enable the two tests timing out with Bazel:
         # - "src/ftxui/component/screen_interactive_test.cpp",
         # - "src/ftxui/dom/selection_test.cpp",
@@ -243,7 +260,10 @@ cc_test(
     ],
     copts = cpp20() + windows_copts(),
     deps = [
-        "//:ftxui",
+        ":screen",
+        ":dom",
+        ":component",
+        "@googletest//:gtest",
         "@googletest//:gtest_main",
     ],
 )

CHANGELOG.md

@@ -4,7 +4,11 @@ Changelog
 Future release
 ------------
 
-6.1.3 (2025-05-01)
+### dom
+- Bugfix: Restore the `dbox` behavior from ftxui 5.0.0. To apply bgcolor
+  blending between the two layers, a new `dboxBlend` will be added.
+
+6.1.8 (2025-05-01)
 ------------------
 
 ### Build
@@ -15,7 +19,7 @@ Future release
 
   **MODULE.bazel**
   ```bazel
-  bazel_dep(name = "ftxui", version = "6.1.3")
+  bazel_dep(name = "ftxui", version = "6.1.8")
   ```
 
   **BUILD.bazel**

CMakeLists.txt

@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.12)
 
 project(ftxui
   LANGUAGES CXX
-  VERSION 6.1.3
+  VERSION 6.1.8
   DESCRIPTION "C++ Functional Terminal User Interface."
 )
 

MODULE.bazel

@@ -1,13 +1,13 @@
-# Copyright 2025 Arthur Sonzogni. All rights reserved.
-# Use of this source code is governed by the MIT license that can be found in
-# the LICENSE file.
+# FTXUI module.
+module(
+    name = "ftxui",
+    version = "6.1.8",
+    compatibility_level = 6,
+)
 
-# FTXUI Module.
-module(name = "ftxui", version = "6.1.3")
-
-# Build deps.
+# Build dependencies.
 bazel_dep(name = "rules_cc", version = "0.1.1")
-bazel_dep(name = "platforms", version = "0.0.11")
+bazel_dep(name = "platforms", version = "0.0.10")
 
-# Test deps.
-bazel_dep(name = "googletest", version = "1.16.0.bcr.1")
+# Test dependencies.
+bazel_dep(name = "googletest", version = "1.14.0.bcr.1", dev_dependency = True)

README.md

@@ -372,7 +372,7 @@ include(FetchContent)
 
 FetchContent_Declare(ftxui
   GIT_REPOSITORY https://github.com/ArthurSonzogni/ftxui
-  GIT_TAG v6.1.3
+  GIT_TAG v6.1.8
 )
 
 FetchContent_GetProperties(ftxui)

bazel/ftxui.bzl

@@ -1,6 +1,7 @@
 # ftxui_common.bzl
 
 load("@rules_cc//cc:defs.bzl", "cc_library")
+load("@rules_cc//cc:defs.bzl", "cc_binary")
 
 def cpp17():
     return select({
@@ -45,7 +46,8 @@ def windows_copts():
       # This
       # - Replace missing font symbols by others.
       # - Reduce screen position pooling frequency to deals against a Microsoft
-      #   race condition. This was fixed in 2020, but clients never not updated.
+      #   race condition. This was fixed in 2020, but clients are still using
+      #   old versions.
       #   - https://github.com/microsoft/terminal/pull/7583
       #   - https://github.com/ArthurSonzogni/FTXUI/issues/136
       "-DFTXUI_MICROSOFT_TERMINAL_FALLBACK",
@@ -71,8 +73,8 @@ def pthread_linkopts():
 
 def ftxui_cc_library(
         name,
-        srcs,
-        hdrs,
+        srcs = [],
+        hdrs = [],
         linkopts = [],
         deps = []):
 
@@ -93,7 +95,8 @@ def ftxui_cc_library(
     )
 
 # Compile all the examples in the examples/ directory.
-# This is useful to check the Bazel is synchronized with CMake definitions.
+# This is useful to check the Bazel is always synchronized against CMake
+# definitions.
 def generate_examples():
     cpp_files = native.glob(["examples/**/*.cpp"])
 
@@ -107,9 +110,13 @@ def generate_examples():
         # Turn "examples/component/button.cpp" → "example_component_button"
         name = src.replace("/", "_").replace(".cpp", "")
 
-        native.cc_binary(
+        cc_binary(
             name = name,
             srcs = [src],
-            deps = ["//:component"],
+            deps = [
+              ":component",
+              ":dom",
+              ":screen",
+            ],
             copts = cpp20() + windows_copts(),
         )

src/ftxui/dom/dbox.cpp

@@ -45,59 +45,6 @@ class DBox : public Node {
       child->SetBox(box);
     }
   }
-
-  void Render(Screen& screen) override {
-    if (children_.size() <= 1) {
-      Node::Render(screen);
-      return;
-    }
-
-    const int width = box_.x_max - box_.x_min + 1;
-    const int height = box_.y_max - box_.y_min + 1;
-    std::vector<Pixel> pixels(std::size_t(width * height));
-
-    for (auto& child : children_) {
-      child->Render(screen);
-
-      // Accumulate the pixels
-      Pixel* acc = pixels.data();
-      for (int x = 0; x < width; ++x) {
-        for (int y = 0; y < height; ++y) {
-          auto& pixel = screen.PixelAt(x + box_.x_min, y + box_.y_min);
-          acc->background_color =
-              Color::Blend(acc->background_color, pixel.background_color);
-          acc->automerge = pixel.automerge || acc->automerge;
-          if (pixel.character.empty()) {
-            acc->foreground_color =
-                Color::Blend(acc->foreground_color, pixel.background_color);
-          } else {
-            acc->blink = pixel.blink;
-            acc->bold = pixel.bold;
-            acc->dim = pixel.dim;
-            acc->inverted = pixel.inverted;
-            acc->italic = pixel.italic;
-            acc->underlined = pixel.underlined;
-            acc->underlined_double = pixel.underlined_double;
-            acc->strikethrough = pixel.strikethrough;
-            acc->hyperlink = pixel.hyperlink;
-            acc->character = pixel.character;
-            acc->foreground_color = pixel.foreground_color;
-          }
-          ++acc;  // NOLINT
-
-          pixel = Pixel();
-        }
-      }
-    }
-
-    // Render the accumulated pixels:
-    Pixel* acc = pixels.data();
-    for (int x = 0; x < width; ++x) {
-      for (int y = 0; y < height; ++y) {
-        screen.PixelAt(x + box_.x_min, y + box_.y_min) = *acc++;  // NOLINT
-      }
-    }
-  }
 };
 }  // namespace
 

tools/test_bazel.sh

@@ -0,0 +1,24 @@
+# This script tests the project with different versions of Bazel and compilers
+# locally. This avoids waiting on the CI to run the tests.
+
+# Version
+# -------
+# - Version >= 7 are supported
+# - Version <= 6 fail with the error:
+#   Error:
+#     external/googletest~1.14.0.bcr.1/googletest/include/gtest/internal/gtest-port.h:279:2:
+#     error: #error C++ versions less than C++14 are not supported.
+for ver in \
+  "7.0.0" \
+  "8.0.0"
+do
+  for cc in \
+    "gcc" \
+    "clang"
+    do
+      echo "=== Testing with Bazel ${ver} with ${cc} ==="
+      USE_BAZEL_VERSION=${ver} CC=${cc} bazel clean --expunge
+      USE_BAZEL_VERSION=${ver} CC=${cc} bazel build //...
+      USE_BAZEL_VERSION=${ver} CC=${cc} bazel test //...
+    done
+  done