One way is UISettings ColorValuesChanged event as @Raymond Chen suggests. Or according to the answer, you can use SystemControlBackgroundAccentBrush to detect.

A basic test in C++/WinRT from a UWP template, where I change the Grid background color when System colors change =>

.h :

 #include "MainPage.g.h"
    
 #include <winrt/Windows.UI.Core.h>
 #include <winrt/Windows.UI.ViewManagement.h>
 #include <winrt/Windows.UI.h>
 #include <winrt/Windows.UI.XAML.Media.h>
    
 namespace winrt::UWP_CPP_WinRT3::implementation
 {
     struct MainPage : MainPageT<MainPage>
     {
         MainPage();
    
         int32_t MyProperty();
         void MyProperty(int32_t value);
    
         void ClickHandler(Windows::Foundation::IInspectable const& sender, Windows::UI::Xaml::RoutedEventArgs const& args);
    
         void NorifyColors()
         {
             colorValuesChangedRevoker = uiSettings.ColorValuesChanged(winrt::auto_revoke, [this](auto&&, auto&&)
                 {
                     Dispatcher().RunAsync(Windows::UI::Core::CoreDispatcherPriority::Normal, [strongThis = get_strong()]()
                     {
                         strongThis->UpdateAccentColor();
                     });
                 });
         }
     private:
         Windows::UI::ViewManagement::UISettings uiSettings;
         Windows::UI::ViewManagement::UISettings::ColorValuesChanged_revoker colorValuesChangedRevoker;
         void UpdateAccentColor();
     };
 }

in .cpp :

 // mainGrid is the main Grid of the main window

 void MainPage::UpdateAccentColor()
 {
     Color accentColor = uiSettings.GetColorValue(Windows::UI::ViewManagement::UIColorType::Accent);
     mainGrid().Background(Windows::UI::Xaml::Media::SolidColorBrush::SolidColorBrush(accentColor));
 }
    
 void MainPage::ClickHandler(IInspectable const&, RoutedEventArgs const&)
 {
     myButton().Content(box_value(L"Clicked"));
     NorifyColors();
 }

welll is there a while loop i can replicate replicate part of it from scratch but I'm stuck the function doesn't want to call itself well how I make this happens
I guess something related to
winrt::BlankApp1::implementation
but how is that
I'm trying to do all of that In a single main.cpp file since i wanna understand the basics first here's where I'm at

include <fstream>

include <iostream>

include <filesystem>

include <chrono>

include <thread>

include <winrt/Windows.UI.Core.h>

include <winrt/Windows.UI.ViewManagement.h>

include <winrt/Windows.UI.h>

include <winrt/Windows.UI.XAML.Media.h>

int wew = 55;
winrt::Windows::UI::ViewManagement::UISettings::ColorValuesChanged_revoker colorValuesChangedRevoker;
winrt::Windows::UI::ViewManagement::UISettings uiSettings;
struct mazin
{
void NorifyColors()
{
colorValuesChangedRevoker = uiSettings.ColorValuesChanged(winrt::auto_revoke, [this](auto&&, auto&&)
{
Dispatcher().RunAsync(Windows::UI::Core::CoreDispatcherPriority::Normal, [strongThis = get_strong()]()
{
strongThis->UpdateAccentColor();
});
});
}
private:
void UpdateAccentColor();
};

void mazin::UpdateAccentColor(){
winrt::Windows::UI::Color accentColor = uiSettings.GetColorValue(winrt::Windows::UI::ViewManagement::UIColorType::Accent);
wew = wew +2 ;
}

int main (){
bool running = true;
if (!std::filesystem::exists("color.inc")) {
running = false;
}
running = true;
while (running)
{
std::cout << wew << std::endl;
}
}

thanks for your help thought @Castorix31

 void MainPage::ClickHandler(IInspectable const&, RoutedEventArgs const&)
 {
     myButton().Content(box_value(L"Clicked"));
     NotifyColors();
 }

   NotifyColors();

Hi Beheeddine,

Thanks for taking time to explain the scenario to us.

If you want to obtain the user’s accent color, you can ask the UI Settings object for the current color value of UIColorType.Accent.

You can find more information about UI Settings here - https://docs.microsoft.com/en-us/uwp/api/Windows.UI.ViewManagement.UISettings?redirectedfrom=MSDN&view=winrt-22000

If you are trying to get the details using C++ app, try following code.

namespace vm = Windows::UI::ViewManagement;

void GetAccentColor()
{
auto settings = ref new vm::UISettings();
auto color = settings->GetColorValue(vm::UIColorType::Accent);
// color.A, color.R, color.G, and color.B are the color channels.
}

in C#, use following code.

using vm = Windows.UI.ViewManagement;

void GetAccentColor()
{
var settings = new vm.UISettings();
var color = settings.GetColorValue(vm.UIColorType.Accent);
// color.A, color.R, color.G, and color.B are the color channels.
}

Also you have following event to check the color type is changed or not.

public event TypedEventHandler<UISettings,object> ColorValuesChanged;

Additional info here - https://docs.microsoft.com/en-us/uwp/api/windows.ui.viewmanagement.uisettings.colorvalueschanged?view=winrt-22000

A batch file with above method can be scheduled to run under windows tasks to monitor the change event.

---

--If the reply is helpful, please Upvote and Accept as answer.--

Thank you!