Flutter Tree

https://github.com/xrr2016/flutter-tree
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A Flutter package for creating and managing hierarchical tree structures with features like...
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### Installation Rules for Flutter Application Bundle

Source: https://github.com/xrr2016/flutter-tree/blob/master/example/windows/CMakeLists.txt

Defines installation rules for the Flutter application, including the executable, support files, assets, and AOT libraries, ensuring correct placement for runtime execution.

```cmake
# === Installation ===
# Support files are copied into place next to the executable, so that it can
# run in place. This is done instead of making a separate bundle (as on Linux)
# so that building and running from within Visual Studio will work.
set(BUILD_BUNDLE_DIR "$<TARGET_FILE_DIR:${BINARY_NAME}>")
# Make the "install" step default, as it's required to run.
set(CMAKE_VS_INCLUDE_INSTALL_TO_DEFAULT_BUILD 1)
if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
  set(CMAKE_INSTALL_PREFIX "${BUILD_BUNDLE_DIR}" CACHE PATH "..." FORCE)
endif()

set(INSTALL_BUNDLE_DATA_DIR "${CMAKE_INSTALL_PREFIX}/data")
set(INSTALL_BUNDLE_LIB_DIR "${CMAKE_INSTALL_PREFIX}")

install(TARGETS ${BINARY_NAME} RUNTIME DESTINATION "${CMAKE_INSTALL_PREFIX}"
  COMPONENT Runtime)

install(FILES "${FLUTTER_ICU_DATA_FILE}" DESTINATION "${INSTALL_BUNDLE_DATA_DIR}"
  COMPONENT Runtime)

install(FILES "${FLUTTER_LIBRARY}" DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
  COMPONENT Runtime)

if(PLUGIN_BUNDLED_LIBRARIES)
  install(FILES "${PLUGIN_BUNDLED_LIBRARIES}"
    DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
    COMPONENT Runtime)
endif()

# Fully re-copy the assets directory on each build to avoid having stale files
# from a previous install.
set(FLUTTER_ASSET_DIR_NAME "flutter_assets")
install(CODE "
  file(REMOVE_RECURSE \"${INSTALL_BUNDLE_DATA_DIR}/${FLUTTER_ASSET_DIR_NAME}\")
  " COMPONENT Runtime)
install(DIRECTORY "${PROJECT_BUILD_DIR}/${FLUTTER_ASSET_DIR_NAME}"
  DESTINATION "${INSTALL_BUNDLE_DATA_DIR}" COMPONENT Runtime)

# Install the AOT library on non-Debug builds only.
install(FILES "${AOT_LIBRARY}" DESTINATION "${INSTALL_BUNDLE_DATA_DIR}"
  CONFIGURATIONS Profile;Release
  COMPONENT Runtime)
```

--------------------------------

### Flutter Tree Example CSS

Source: https://github.com/xrr2016/flutter-tree/blob/master/example/web/index.html

CSS styles for the Flutter tree example, including centering elements and defining animations for a chase-dot spinner.

```css
html, body { height: 100%; width: 100%; }
.center { align-items: center; display: flex; justify-content: center; height: 100%; width: 100%; }
/* Credits: https://tobiasahlin.com/spinkit/ */
.sk-chase {
  width: 40px;
  height: 40px;
  position: relative;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  animation: sk-chase 2.5s infinite linear both;
}
.sk-chase-dot {
  width: 100%;
  height: 100%;
  position: absolute;
  left: 0;
  top: 0;
  animation: sk-chase-dot 2s infinite ease-in-out both;
}
.sk-chase-dot:before {
  content: "";
  display: block;
  width: 25%;
  height: 25%;
  border-radius: 100%;
  background-color: #1389fd;
  animation: sk-chase-dot-before 2s infinite ease-in-out both;
}
.sk-chase-dot:nth-child(1) {
  animation-delay: -1.1s;
}
.sk-chase-dot:nth-child(2) {
  animation-delay: -1s;
}
.sk-chase-dot:nth-child(3) {
  animation-delay: -0.9s;
}
.sk-chase-dot:nth-child(4) {
  animation-delay: -0.8s;
}
.sk-chase-dot:nth-child(5) {
  animation-delay: -0.7s;
}
.sk-chase-dot:nth-child(6) {
  animation-delay: -0.6s;
}
.sk-chase-dot:nth-child(1):before {
  animation-delay: -1.1s;
}
.sk-chase-dot:nth-child(2):before {
  animation-delay: -1s;
}
.sk-chase-dot:nth-child(3):before {
  animation-delay: -0.9s;
}
.sk-chase-dot:nth-child(4):before {
  animation-delay: -0.8s;
}
.sk-chase-dot:nth-child(5):before {
  animation-delay: -0.7s;
}
.sk-chase-dot:nth-child(6):before {
  animation-delay: -0.6s;
}
@keyframes sk-chase {
  100% {
    transform: rotate(360deg);
  }
}
@keyframes sk-chase-dot {
  80%, 100% {
    transform: rotate(360deg);
  }
}
@keyframes sk-chase-dot-before {
  50% {
    transform: scale(0.4);
  }
  100%, 0% {
    transform: scale(1);
  }
}
```

--------------------------------

### Flutter Library Setup

Source: https://github.com/xrr2016/flutter-tree/blob/master/example/windows/flutter/CMakeLists.txt

Configures the Flutter library, including its DLL, headers, and ICU data file. It also sets up include directories and links against the Flutter library.

```cmake
cmake_minimum_required(VERSION 3.14)

set(EPHEMERAL_DIR "${CMAKE_CURRENT_SOURCE_DIR}/ephemeral")

# Configuration provided via flutter tool.
include(${EPHEMERAL_DIR}/generated_config.cmake)

# TODO: Move the rest of this into files in ephemeral. See
# https://github.com/flutter/flutter/issues/57146.
set(WRAPPER_ROOT "${EPHEMERAL_DIR}/cpp_client_wrapper")

# === Flutter Library ===
set(FLUTTER_LIBRARY "${EPHEMERAL_DIR}/flutter_windows.dll")

# Published to parent scope for install step.
set(FLUTTER_LIBRARY ${FLUTTER_LIBRARY} PARENT_SCOPE)
set(FLUTTER_ICU_DATA_FILE "${EPHEMERAL_DIR}/icudtl.dat" PARENT_SCOPE)
set(PROJECT_BUILD_DIR "${PROJECT_DIR}/build/" PARENT_SCOPE)
set(AOT_LIBRARY "${PROJECT_DIR}/build/windows/app.so" PARENT_SCOPE)

list(APPEND FLUTTER_LIBRARY_HEADERS
  "flutter_export.h"
  "flutter_windows.h"
  "flutter_messenger.h"
  "flutter_plugin_registrar.h"
  "flutter_texture_registrar.h"
)
list(TRANSFORM FLUTTER_LIBRARY_HEADERS PREPEND "${EPHEMERAL_DIR}/")
add_library(flutter INTERFACE)
target_include_directories(flutter INTERFACE
  "${EPHEMERAL_DIR}"
)
target_link_libraries(flutter INTERFACE "${FLUTTER_LIBRARY}.lib")
add_dependencies(flutter flutter_assemble)
```

--------------------------------

### Install flutter_tree

Source: https://github.com/xrr2016/flutter-tree/blob/master/readme.v1.md

Add the flutter_tree package to your project's dependencies in the pubspec.yaml file.

```yml
dependencies:
  flutter_tree: ^1.0.0
```

--------------------------------

### Install flutter_tree Package

Source: https://github.com/xrr2016/flutter-tree/blob/master/README.md

Add the flutter_tree package to your project's dependencies in the pubspec.yaml file to install it.

```yml
dependencies:
  flutter_tree: ^2.0.0
```

--------------------------------

### CMake Project Setup and Build Modes

Source: https://github.com/xrr2016/flutter-tree/blob/master/example/windows/CMakeLists.txt

Configures the CMake project, sets the minimum version, project name, and manages build types (Debug, Profile, Release) based on whether the generator is multi-config.

```cmake
cmake_minimum_required(VERSION 3.14)
project(example LANGUAGES CXX)

set(BINARY_NAME "example")

cmake_policy(SET CMP0063 NEW)

set(CMAKE_INSTALL_RPATH "$ORIGIN/lib")

# Configure build options.
get_property(IS_MULTICONFIG GLOBAL PROPERTY GENERATOR_IS_MULTI_CONFIG)
if(IS_MULTICONFIG)
  set(CMAKE_CONFIGURATION_TYPES "Debug;Profile;Release"
    CACHE STRING "" FORCE)
else()
  if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
    set(CMAKE_BUILD_TYPE "Debug" CACHE
      STRING "Flutter build mode" FORCE)
    set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS
      "Debug" "Profile" "Release")
  endif()
endif()

set(CMAKE_EXE_LINKER_FLAGS_PROFILE "${CMAKE_EXE_LINKER_FLAGS_RELEASE}")
set(CMAKE_SHARED_LINKER_FLAGS_PROFILE "${CMAKE_SHARED_LINKER_FLAGS_RELEASE}")
set(CMAKE_C_FLAGS_PROFILE "${CMAKE_C_FLAGS_RELEASE}")
set(CMAKE_CXX_FLAGS_PROFILE "${CMAKE_CXX_FLAGS_RELEASE}")
```

--------------------------------

### Flutter Service Worker and App Loading

Source: https://github.com/xrr2016/flutter-tree/blob/master/example/web/index.html

JavaScript code for managing Flutter application loading, including service worker registration, version checking, and fallback mechanisms. It also handles the 'flutter-first-frame' event to remove loading indicators.

```javascript
var serviceWorkerVersion = null;
var scriptLoaded = false;

function loadMainDartJs() {
  if (scriptLoaded) {
    return;
  }
  scriptLoaded = true;
  var scriptTag = document.createElement("script");
  scriptTag.src = "main.dart.js";
  scriptTag.type = "application/javascript";
  document.body.append(scriptTag);
}

if ("serviceWorker" in navigator) {
  // Service workers are supported. Use them.
  window.addEventListener("load", function () {
    // Wait for registration to finish before dropping the <script> tag.
    // Otherwise, the browser will load the script multiple times,
    // potentially different versions.
    var serviceWorkerUrl = "flutter_service_worker.js?v=" + serviceWorkerVersion;
    navigator.serviceWorker.register(serviceWorkerUrl).then((reg) => {
      function waitForActivation(serviceWorker) {
        serviceWorker.addEventListener("statechange", () => {
          if (serviceWorker.state == "activated") {
            console.log("Installed new service worker.");
            loadMainDartJs();
          }
        });
      }

      if (!reg.active && (reg.installing || reg.waiting)) {
        // No active web worker and we have installed or are installing
        // one for the first time. Simply wait for it to activate.
        waitForActivation(reg.installing || reg.waiting);
      } else if (!reg.active.scriptURL.endsWith(serviceWorkerVersion)) {
        // When the app updates the serviceWorkerVersion changes, so we
        // need to ask the service worker to update.
        console.log("New service worker available.");
        reg.update();
        waitForActivation(reg.installing);
      } else {
        // Existing service worker is still good. console.log("Loading app from service worker.");
        loadMainDartJs();
      }
    });

    // If service worker doesn't succeed in a reasonable amount of time,
    // fallback to plaint <script> tag.
    setTimeout(() => {
      if (!scriptLoaded) {
        console.warn("Failed to load app from service worker. Falling back to plain <script> tag.");
        loadMainDartJs();
      }
    }, 4000);
  });
} else {
  // Service workers not supported. Just drop the <script> tag.
  loadMainDartJs();
}

window.addEventListener("flutter-first-frame", function () {
  console.log("flutter app loaded.");
  document.getElementById("loading").remove();
});
```

--------------------------------

### TreeView Configuration

Source: https://github.com/xrr2016/flutter-tree/blob/master/readme.v1.md

Outlines the configurable properties for the TreeView widget, including the data source, keys for data mapping, padding, and tap event callbacks.

```APIDOC
TreeView Properties:
  data: List<Map<String, dynamic>> (required: true) - The hierarchical data for the tree.
  titleKey: string (default: 'title') - The key in the map that holds the title.
  leadingKey: string (default: 'leading') - The key in the map that holds the leading widget identifier.
  expanedKey: string (default: 'expaned') - The key in the map that indicates if the item is expanded.
  childrenKey: string (default: 'children') - The key in the map that holds the list of child items.
  offsetLeft: double (default: 24.0) - Padding to the left for each item.
  titleOnTap: Function (default: null) - Callback when a title is tapped.
  leadingOnTap: Function (default: null) - Callback when a leading widget is tapped.
  trailingOnTap: Function (default: null) - Callback when a trailing widget is tapped.
```

--------------------------------

### TreeNode Configuration

Source: https://github.com/xrr2016/flutter-tree/blob/master/readme.v1.md

Details the configurable properties for the TreeNode widget, including level, expansion state, padding, child widgets, leading/trailing widgets, and tap callbacks.

```APIDOC
TreeNode Properties:
  level: int (default: 0) - Item indent level.
  expaned: boolean (default: false) - Whether the item is expanded.
  offsetLeft: double (default: 24.0) - Padding to the left of the item.
  children: List<Widget> (default: []) - Child widgets for the item.
  title: Widget (default: Text('Title')) - The main title widget for the item.
  leading: Widget (default: IconButton()) - Widget displayed before the title.
  trailing: Widget (default: IconButton()) - Widget displayed after the title.
  titleOnTap: Function (default: null) - Callback when the title is tapped.
  leadingOnTap: Function (default: null) - Callback when the leading widget is tapped.
  trailingOnTap: Function (default: null) - Callback when the trailing widget is tapped.
```

--------------------------------

### Flutter Tool Backend Integration

Source: https://github.com/xrr2016/flutter-tree/blob/master/example/windows/flutter/CMakeLists.txt

Configures a custom command to run the Flutter tool backend, which is responsible for assembling Flutter resources. It uses a phony target to ensure execution.

```cmake
# === Flutter tool backend ===
# _phony_ is a non-existent file to force this command to run every time,
# since currently there's no way to get a full input/output list from the
# flutter tool.
set(PHONY_OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/_phony_")
set_source_files_properties("${PHONY_OUTPUT}" PROPERTIES SYMBOLIC TRUE)
add_custom_command(
  OUTPUT ${FLUTTER_LIBRARY} ${FLUTTER_LIBRARY_HEADERS}
    ${CPP_WRAPPER_SOURCES_CORE} ${CPP_WRAPPER_SOURCES_PLUGIN}
    ${CPP_WRAPPER_SOURCES_APP}
    ${PHONY_OUTPUT}
  COMMAND ${CMAKE_COMMAND} -E env
    ${FLUTTER_TOOL_ENVIRONMENT}
    "${FLUTTER_ROOT}/packages/flutter_tools/bin/tool_backend.bat"
      windows-x64 $<CONFIG>
  VERBATIM
)
add_custom_target(flutter_assemble DEPENDS
  "${FLUTTER_LIBRARY}"
  ${FLUTTER_LIBRARY_HEADERS}
  ${CPP_WRAPPER_SOURCES_CORE}
  ${CPP_WRAPPER_SOURCES_PLUGIN}
  ${CPP_WRAPPER_SOURCES_APP}
)
```

--------------------------------

### CMake Build Configuration for Flutter Project

Source: https://github.com/xrr2016/flutter-tree/blob/master/example/windows/runner/CMakeLists.txt

This snippet defines the core build settings for a Flutter project using CMake. It specifies the minimum required CMake version, the project name, and configures the main executable target with its source files, standard settings, compile definitions, linked libraries, include directories, and build dependencies.

```cmake
cmake_minimum_required(VERSION 3.14)
project(runner LANGUAGES CXX)

add_executable(${BINARY_NAME} WIN32
  "flutter_window.cpp"
  "main.cpp"
  "utils.cpp"
  "win32_window.cpp"
  "${FLUTTER_MANAGED_DIR}/generated_plugin_registrant.cc"
  "Runner.rc"
  "runner.exe.manifest"
)
apply_standard_settings(${BINARY_NAME})
target_compile_definitions(${BINARY_NAME} PRIVATE "NOMINMAX")
target_link_libraries(${BINARY_NAME} PRIVATE flutter flutter_wrapper_app)
target_include_directories(${BINARY_NAME} PRIVATE "${CMAKE_SOURCE_DIR}")
add_dependencies(${BINARY_NAME} flutter_assemble)
```

--------------------------------

### Apply Standard Compilation Settings

Source: https://github.com/xrr2016/flutter-tree/blob/master/example/windows/CMakeLists.txt

A CMake function to apply common compilation features, options, and definitions to a target, including C++17 standard, warning levels, and exception handling.

```cmake
# Use Unicode for all projects.
add_definitions(-DUNICODE -D_UNICODE)

# Compilation settings that should be applied to most targets.
function(APPLY_STANDARD_SETTINGS TARGET)
  target_compile_features(${TARGET} PUBLIC cxx_std_17)
  target_compile_options(${TARGET} PRIVATE /W4 /WX /wd"4100")
  target_compile_options(${TARGET} PRIVATE /EHsc)
  target_compile_definitions(${TARGET} PRIVATE "_HAS_EXCEPTIONS=0")
  target_compile_definitions(${TARGET} PRIVATE "$<$<CONFIG:Debug>:_DEBUG>")
endfunction()
```

--------------------------------

### Customize Launch Screen via Xcode

Source: https://github.com/xrr2016/flutter-tree/blob/master/example/ios/Runner/Assets.xcassets/LaunchImage.imageset/README.md

Instructions on how to customize the Flutter project's launch screen assets using Xcode. This involves opening the Xcode project and replacing images in the Assets.xcassets folder.

```bash
open ios/Runner.xcworkspace

Select Runner/Assets.xcassets in the Project Navigator and drop in the desired images.
```

--------------------------------

### C++ Wrapper for Plugins

Source: https://github.com/xrr2016/flutter-tree/blob/master/example/windows/flutter/CMakeLists.txt

Defines a static library for the C++ wrapper used by Flutter plugins. It includes core and plugin-specific sources and links against the Flutter library.

```cmake
# === Wrapper ===
list(APPEND CPP_WRAPPER_SOURCES_CORE
  "core_implementations.cc"
  "standard_codec.cc"
)
list(TRANSFORM CPP_WRAPPER_SOURCES_CORE PREPEND "${WRAPPER_ROOT}/")
list(APPEND CPP_WRAPPER_SOURCES_PLUGIN
  "plugin_registrar.cc"
)
list(TRANSFORM CPP_WRAPPER_SOURCES_PLUGIN PREPEND "${WRAPPER_ROOT}/")
list(APPEND CPP_WRAPPER_SOURCES_APP
  "flutter_engine.cc"
  "flutter_view_controller.cc"
)
list(TRANSFORM CPP_WRAPPER_SOURCES_APP PREPEND "${WRAPPER_ROOT}/")

# Wrapper sources needed for a plugin.
add_library(flutter_wrapper_plugin STATIC
  ${CPP_WRAPPER_SOURCES_CORE}
  ${CPP_WRAPPER_SOURCES_PLUGIN}
)
apply_standard_settings(flutter_wrapper_plugin)
set_target_properties(flutter_wrapper_plugin PROPERTIES
  POSITION_INDEPENDENT_CODE ON)
set_target_properties(flutter_wrapper_plugin PROPERTIES
  CXX_VISIBILITY_PRESET hidden)
target_link_libraries(flutter_wrapper_plugin PUBLIC flutter)
target_include_directories(flutter_wrapper_plugin PUBLIC
  "${WRAPPER_ROOT}/include"
)
add_dependencies(flutter_wrapper_plugin flutter_assemble)
```

--------------------------------

### TreeView Usage

Source: https://github.com/xrr2016/flutter-tree/blob/master/readme.v1.md

Shows how to use the TreeView widget to display hierarchical data. The data is provided as a list of maps, and callbacks can be defined for tap events on the title, leading, and trailing widgets.

```dart
final List<Map<String, dynamic>> treeData = [
  {
    "title": "Title",
    "expaned": true,
    "children": [
      {
        "title": "Title",
        "expaned": true,
        "children": [],
      },
    ],
  }
];

TreeView(
  data: treeData,
  titleOnTap: () {
    print('title');
  },
  leadingOnTap: () {
    print('leading');
  },
  trailingOnTap: () {
    print('trailing');
  },
)
```

--------------------------------

### Basic TreeView Usage

Source: https://github.com/xrr2016/flutter-tree/blob/master/README.md

Renders a basic tree view using the TreeView widget with the provided tree data.

```dart
TreeView(data: treeData)
```

--------------------------------

### Data Mapping and Tree Generation

Source: https://github.com/xrr2016/flutter-tree/blob/master/README.md

Demonstrates how to map server data to the TreeNodeData format and generate the tree data structure required by the TreeView widget. Includes a recursive function for mapping nested children.

```dart

/// Your server data
final serverData = [
  {
    "checked": true,
    "children": [
      {
        "checked": true,
        "show": false,
        "children": [],
        "id": 11,
        "pid": 1,
        "text": "Child title 11",
      },
    ],
    "id": 1,
    "pid": 0,
    "show": false,
    "text": "Parent title 1",
  },
  {
    "checked": true,
    "show": false,
    "children": [],
    "id": 2,
    "pid": 0,
    "text": "Parent title 2",
  },
  {
    "checked": true,
    "children": [],
    "id": 3,
    "pid": 0,
    "show": false,
    "text": "Parent title 3",
  },
];

/// Map server data to tree node data
TreeNodeData mapServerDataToTreeData(Map data) {
  return TreeNodeData(
    extra: data,
    title: data['text'],
    expaned: data['show'],
    checked: data['checked'],
    children:
        List.from(data['children'].map((x) => mapServerDataToTreeData(x))),
  );
}

/// Generate tree data
List<TreeNodeData> treeData = List.generate(
  serverData.length,
  (index) => mapServerDataToTreeData(serverData[index]),
);

```

--------------------------------

### Flutter Project Structure and Subdirectories

Source: https://github.com/xrr2016/flutter-tree/blob/master/example/windows/CMakeLists.txt

Includes the Flutter managed directory and the runner subdirectory, along with generated plugin build rules, to integrate Flutter components into the CMake build.

```cmake
set(FLUTTER_MANAGED_DIR "${CMAKE_CURRENT_SOURCE_DIR}/flutter")

# Flutter library and tool build rules.
add_subdirectory(${FLUTTER_MANAGED_DIR})

# Application build
add_subdirectory("runner")

# Generated plugin build rules, which manage building the plugins and adding
# them to the application.
include(flutter/generated_plugins.cmake)
```

--------------------------------

### Flutter Tree Component Properties

Source: https://github.com/xrr2016/flutter-tree/blob/master/README.md

Defines the configurable properties for the Flutter Tree component. These include data binding, lazy loading, visual elements like icons and padding, and event handlers for node interactions such as tapping, expanding, collapsing, checking, appending, and removing nodes.

```APIDOC
FlutterTreeComponent:
  data: List<TreeNodeData>
    - Type: List<TreeNodeData>
    - Description: The data for the tree.
    - Required: true
    - Default: []

  lazy: bool
    - Description: Enables lazy loading for node data.
    - Required: false
    - Default: false

  icon: Widget
    - Description: The icon to display for tree nodes.
    - Required: false
    - Default: Icons.expand_more

  offsetLeft: double
    - Description: Padding applied to the left side of tree items.
    - Required: false
    - Default: 24.0

  showFilter: bool
    - Description: Controls the visibility of the tree filter.
    - Required: false
    - Default: false

  showActions: bool
    - Description: Controls the visibility of node action buttons.
    - Required: false
    - Default: false

  showCheckBox: bool
    - Description: Controls the visibility of checkboxes for nodes.
    - Required: false
    - Default: false

  onTap: Function(TreeNodeData)
    - Description: Callback function executed when a node is tapped.
    - Required: false
    - Default: null

  onExpand: Function(TreeNodeData)
    - Description: Callback function executed when a node is expanded.
    - Required: false
    - Default: null

  onLoad: Function(TreeNodeData)
    - Description: Callback function for lazy loading node data.
    - Required: false
    - Default: null

  onCollapse: Function(TreeNodeData)
    - Description: Callback function executed when a node is collapsed.
    - Required: false
    - Default: null

  onCheck: Function(bool, TreeNodeData)
    - Description: Callback function executed when a node's checkbox state changes.
    - Required: false
    - Default: null

  onAppend: Function(TreeNodeData, TreeNodeData)
    - Description: Callback function for appending a child node.
    - Required: false
    - Default: null

  onRemove: Function(TreeNodeData, TreeNodeData)
    - Description: Callback function for removing a node.
    - Required: false
    - Default: null

  append: Function(TreeNodeData)
    - Description: Function to append a node.
    - Required: false
    - Default: null

  load: Future<List<TreeNodeData>> Function(TreeNodeData)
    - Description: Function to load node data asynchronously.
    - Required: false
    - Default: null
```

--------------------------------

### C++ Wrapper for Runner Application

Source: https://github.com/xrr2016/flutter-tree/blob/master/example/windows/flutter/CMakeLists.txt

Defines a static library for the C++ wrapper used by the Flutter runner application. It includes core and application-specific sources and links against the Flutter library.

```cmake
# Wrapper sources needed for the runner.
add_library(flutter_wrapper_app STATIC
  ${CPP_WRAPPER_SOURCES_CORE}
  ${CPP_WRAPPER_SOURCES_APP}
)
apply_standard_settings(flutter_wrapper_app)
target_link_libraries(flutter_wrapper_app PUBLIC flutter)
target_include_directories(flutter_wrapper_app PUBLIC
  "${WRAPPER_ROOT}/include"
)
add_dependencies(flutter_wrapper_app flutter_assemble)
```

--------------------------------

### TreeView with Event Bindings

Source: https://github.com/xrr2016/flutter-tree/blob/master/README.md

Configures various event handlers for the TreeView, including `onTap`, `onCheck`, `onCollapse`, `onExpand`, `onAppend`, and `onRemove`. These callbacks provide information about user interactions with the tree nodes.

```dart
TreeView(
  data: treeData,
  showActions: true,
  showCheckBox: true,
  append: (parent) {
    return TreeNodeData(
      title: 'Appended',
      expaned: true,
      checked: true,
      children: [],
    );
  },
  onTap: (node) {
    print(node.extra);
  },
  onCheck: (checked, node) {
    print(checked);
    print(node.extra);
  },
  onCollapse: (node) {
    print(node.extra);
  },
  onExpand: (node) {
    print(node.extra);
  },
  onAppend: (node, parent) {
    print(node.extra);
    print(parent.extra);
  },
  onRemove: (node, parent) {
    print(node.extra);
    print(parent.extra);
  },
)
```

--------------------------------

### TreeNode Usage

Source: https://github.com/xrr2016/flutter-tree/blob/master/readme.v1.md

Demonstrates how to create a TreeNode widget, which represents a single item in the tree. It can have nested children to form a hierarchical structure.

```dart
TreeNode(
  title: Text('This is a title!'),
  children: [
    TreeNode(
      title: Text('This is a title!'),
      children: <Widget>[
        TreeNode(title: Text('This is a title!')),
      ],
    ),
  ],
)
```

--------------------------------

### TreeView with Checkboxes

Source: https://github.com/xrr2016/flutter-tree/blob/master/README.md

Displays checkboxes next to each tree node by setting the `showCheckBox` property to true.

```dart
TreeView(
  data: treeData,
  showCheckBox: true,
)
```

--------------------------------

### TreeView with Lazy Loading

Source: https://github.com/xrr2016/flutter-tree/blob/master/README.md

Implements lazy loading for the tree view by setting the `lazy` property to true and providing a `load` callback function. This function asynchronously fetches and returns child nodes when a parent node is expanded.

```dart

/// Create your load function, return list of TreeNodeData

Future<List<TreeNodeData>> _load(TreeNodeData parent) async {
  await Future.delayed(const Duration(seconds: 1));
  final data = [
    TreeNodeData(
      title: 'load1',
      expaned: false,
      checked: true,
      children: [],
      extra: null,
    ),
    TreeNodeData(
      title: 'load2',
      expaned: false,
      checked: false,
      children: [],
      extra: null,
    ),
  ];

  return data;
}

TreeView(
  data: treeData,
  lazy: true,
  load: _load,
  onLoad: (node) {
    print('onLoad');
    print(node.extra);
  },
)

```

--------------------------------

### TreeView with Show Filter

Source: https://github.com/xrr2016/flutter-tree/blob/master/README.md

Enables a filter UI element within the tree view by setting the `showFilter` property to true.

```dart
TreeView(
  data: treeData,
  showFilter: true,
)
```

--------------------------------

### TreeView with Custom Append Action

Source: https://github.com/xrr2016/flutter-tree/blob/master/README.md

Allows users to append new nodes to the tree by providing an `append` callback function. This function receives the parent node and returns a new TreeNodeData.

```dart
TreeView(
  data: treeData,
  showActions: true,
  showCheckBox: true,
  append: (parent) {
    print(parent.extra);
    return TreeNodeData(
      title: 'Appended',
      expaned: true,
      checked: true,
      children: [],
    );
  },
)
```
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