C#•11mo ago

EventHandler not triggering.

in Program.cs

namespace ClipboardHistoryCLI
{
    internal class Program
    {
        static void Main(string[] args)
        {
            ClipboardHandler handler = new ClipboardHandler();

            CommandParser parser = new CommandParser(args);
            string[] list;

            list = parser.ListComponents();
            Console.WriteLine($"{list} TEST");

            do
            {
                Console.WriteLine("HI");
                Thread.Sleep(1000);
            }
            while (true);
        }
    }
}

namespace ClipboardHistoryCLI
{
    internal class Program
    {
        static void Main(string[] args)
        {
            ClipboardHandler handler = new ClipboardHandler();

            CommandParser parser = new CommandParser(args);
            string[] list;

            list = parser.ListComponents();
            Console.WriteLine($"{list} TEST");

            do
            {
                Console.WriteLine("HI");
                Thread.Sleep(1000);
            }
            while (true);
        }
    }
}

in ClipboardHandler.cs:

namespace ClipboardHistoryCLI._Clipboard
{
    internal class ClipboardHandler
    {
        private Dictionary<string, DataPackageView> _clipboardHistory = [];

        public ClipboardHandler()
        {
            Clipboard.ContentChanged += new EventHandler<object>(this.ClipboardChanged);
        }

        private void ClipboardChanged(object? sender, object e)
        {
            Console.WriteLine("TEST");
            Console.WriteLine($"{sender}, {e}");
            Console.WriteLine($"{sender.GetType()}, {e.GetType()}");
        }

namespace ClipboardHistoryCLI._Clipboard
{
    internal class ClipboardHandler
    {
        private Dictionary<string, DataPackageView> _clipboardHistory = [];

        public ClipboardHandler()
        {
            Clipboard.ContentChanged += new EventHandler<object>(this.ClipboardChanged);
        }

        private void ClipboardChanged(object? sender, object e)
        {
            Console.WriteLine("TEST");
            Console.WriteLine($"{sender}, {e}");
            Console.WriteLine($"{sender.GetType()}, {e.GetType()}");
        }

Wrote a very basic setup to learn to work with an EventHandler. The event however does not trigger, I had wrapped Main into an async method, I made ClipboardChanged async, i added an async delay on the main keep-alive loop, nothing worked for me. Any idea why the EventHandler doesnt trigger? ClipboardChanged is an official UWP EventHandler: https://learn.microsoft.com/en-us/uwp/api/windows.applicationmodel.datatransfer.clipboard.contentchanged?view=winrt-22621

Clipboard.ContentChanged Event (Windows.ApplicationModel.DataTransf...

Occurs when the data stored in the Clipboard changes.

15 Replies

Jimmacle•11mo ago

FWIW, the explicit EventHandler is outdated, you can just Clipboard.ContentChanged += ClipboardChanged; have you put a breakpoint in the handler to see if it's really triggering or not?

PogoOP•11mo ago

weird that they didnt update their own docs? how do i add a breakpoint in VS?

Jimmacle•11mo ago

click in the left hand gutter, that's how it works in rider anyway

Buddy•11mo ago

Isn't it the clipboard history API?

PogoOP•11mo ago

yep found it

Clipboard.ContentChanged += new EventHandler<object>(this.TrackClipboardChanges_EventHandler);

Clipboard.ContentChanged += new EventHandler<object>(this.TrackClipboardChanges_EventHandler);

Buddy•11mo ago

Press Windows key + V

PogoOP•11mo ago

there's a clipboard HISTORY api and a normal one clipboard history changed and regular clipboard content changed (i want to track when new content entered the current clipboard) though I dont understand what im doing wrong, is my eventhandler incorrect? is my keep alive loop incorrect?

Buddy•11mo ago

Never used said API, but this seems interesting

You can only access the clipboard when the calling application is in focus on the UI thread (for example, when its CoreWindow is active). Use the CoreWindow.Activated event to track the state of the calling app.

https://learn.microsoft.com/en-us/uwp/api/windows.applicationmodel.datatransfer.clipboard?view=winrt-22621

PogoOP•11mo ago

also no, clipboardchanged did not even trigger

Buddy•11mo ago

Which may be an API exclusive to UWP applications

PogoOP•11mo ago

well, i use the UWP framework but

Buddy•11mo ago

As console applications does not have a UI Thread

PogoOP•11mo ago

they explicitly want me to instance a CoreWindow..? bro why do they do this they do this with every application ever how about if i spawn an invisible CoreWindow no actual window anywhere it just 'exists'

Jimmacle•11mo ago

sounds like a security thing if they want the window to be in focus

PogoOP•11mo ago

yet their own clipboard history app is allowed to grrr

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EventHandler not triggering.