How can I extend the title bar into the client area in a React Native Windows app?

Question

I'm working on a React Native Windows app and want to customize the title bar by extending it into the client area, making it transparent. I'm using C++/WinRT to handle the native side of things. Here's what I have in my App.cpp file:

void App::OnLaunched(activation::LaunchActivatedEventArgs const &e)
{
    super::OnLaunched(e);

    // Ensure the root frame is initialized
    Frame rootFrame = Window::Current().Content().as<Frame>();
    if (!rootFrame)
    {
        rootFrame = Frame();
        Window::Current().Content(rootFrame);
    }

    rootFrame.Navigate(xaml_typename<MainPage>(), box_value(e.Arguments()));

    // Set title bar colors
    auto view = ApplicationView::GetForCurrentView();
    view.TitleBar().BackgroundColor(Windows::UI::Colors::Transparent());
    view.TitleBar().ButtonBackgroundColor(Windows::UI::Colors::Transparent());

    // Use custom title bar
    SetupCustomTitleBar();

    // Show the window
    Window::Current().Activate();
}

void App::SetupCustomTitleBar()
{
    auto coreTitleBar = Windows::ApplicationModel::Core::CoreApplication::GetCurrentView().TitleBar();
    coreTitleBar.ExtendViewIntoTitleBar(true);
}

And here is the App.h file:

#pragma once

#include "App.xaml.g.h"
#include <CppWinRTIncludes.h>

namespace activation = winrt::Windows::ApplicationModel::Activation;

namespace winrt::AChat::implementation
{
  struct App : AppT<App>
  {
    App() noexcept;
    void OnLaunched(activation::LaunchActivatedEventArgs const &);
    void OnActivated(Windows::ApplicationModel::Activation::IActivatedEventArgs const &e);
    void OnSuspending(IInspectable const &, Windows::ApplicationModel::SuspendingEventArgs const &);
    void OnNavigationFailed(IInspectable const &, xaml::Navigation::NavigationFailedEventArgs const &);

  private:
    using super = AppT<App>;

  private:
    void SetupCustomTitleBar();
  };
} // namespace winrt::AChat::implementation

Despite this, I'm not seeing the title bar extend into the client area. What am I missing or doing wrong?

The code you've provided is almost correct, but there are a few additional steps and considerations to ensure that the title bar extends correctly into the client area:

Handle Title Bar Events: The custom title bar might not behave as expected if you don't handle pointer events and other title bar-related events correctly. You'll need to hook into these events and ensure the title bar area responds appropriately.

Set Custom Title Bar: In addition to extending the view into the title bar, you should also call SetTitleBar with your XAML element that will act as the draggable region of the title bar.

Here's how you can update your code:

void App::SetupCustomTitleBar()
{
    auto coreTitleBar = Windows::ApplicationModel::Core::CoreApplication::GetCurrentView().TitleBar();
    coreTitleBar.ExtendViewIntoTitleBar(true);

    // Assuming you have a XAML element called TitleBar that you want to use as the custom title bar
    Window::Current().SetTitleBar(Window::Current().Content().as<MainPage>().TitleBar());

    // Hook into title bar events for further customization if needed
    coreTitleBar.LayoutMetricsChanged([this](auto, auto)
    {
        // Adjust the content based on the new layout metrics, if needed
    });

    coreTitleBar.IsVisibleChanged([this](auto, auto)
    {
        // Handle visibility changes, if needed
    });
}

Make sure that in your XAML code (MainPage.xaml or wherever your main content is defined), you have defined a Grid or another element with the Name="TitleBar" that will serve as the title bar. This will allow the system to recognize it as the draggable region of the window.

By extending the view into the title bar and setting a custom title bar, you ensure that your React Native Windows app uses the entire window space effectively, providing a sleek, modern look.