C#•17mo ago

❔ Allow service to interact with desktop

public const int KEYEVENTF_EXTENTEDKEY = 1;
        public const int KEYEVENTF_KEYUP = 0;
        public const int VK_MEDIA_NEXT_TRACK = 0xB0;
        public const int VK_MEDIA_PLAY_PAUSE = 0xB3;
        public const int VK_MEDIA_PREV_TRACK = 0xB1;

        [DllImport("user32.dll")]
        public static extern void keybd_event(byte virtualKey, byte scanCode, uint flags, IntPtr extraInfo);
keybd_event(VK_MEDIA_PREV_TRACK, 0, KEYEVENTF_EXTENTEDKEY, IntPtr.Zero);    // PREV

public const int KEYEVENTF_EXTENTEDKEY = 1;
        public const int KEYEVENTF_KEYUP = 0;
        public const int VK_MEDIA_NEXT_TRACK = 0xB0;
        public const int VK_MEDIA_PLAY_PAUSE = 0xB3;
        public const int VK_MEDIA_PREV_TRACK = 0xB1;

        [DllImport("user32.dll")]
        public static extern void keybd_event(byte virtualKey, byte scanCode, uint flags, IntPtr extraInfo);
keybd_event(VK_MEDIA_PREV_TRACK, 0, KEYEVENTF_EXTENTEDKEY, IntPtr.Zero);    // PREV

this code works properly in windows form but it doesn't in windows service so i found i need to allow service to interact with desktop so i tried but it doesn't work neither

53 Replies

ero•17mo ago

that's crazy, you've been told to use SendInput instead of keydb_event and you still didn't change it

어부지망생•17mo ago

What does it mean? Ah i tried them But it doesnt work

var input = new INPUT[2];

                            input[0].type = INPUT_TYPE.INPUT_KEYBOARD;
                            input[0].Anonymous.ki.wVk = VIRTUAL_KEY.VK_MEDIA_NEXT_TRACK;

                            input[1].type = INPUT_TYPE.INPUT_KEYBOARD;
                            input[1].Anonymous.ki.wVk = VIRTUAL_KEY.VK_MEDIA_NEXT_TRACK;
                            input[1].Anonymous.ki.dwFlags = KEYBD_EVENT_FLAGS.KEYEVENTF_KEYUP;

                            PInvoke.SendInput(input, Marshal.SizeOf<INPUT>());

var input = new INPUT[2];

                            input[0].type = INPUT_TYPE.INPUT_KEYBOARD;
                            input[0].Anonymous.ki.wVk = VIRTUAL_KEY.VK_MEDIA_NEXT_TRACK;

                            input[1].type = INPUT_TYPE.INPUT_KEYBOARD;
                            input[1].Anonymous.ki.wVk = VIRTUAL_KEY.VK_MEDIA_NEXT_TRACK;
                            input[1].Anonymous.ki.dwFlags = KEYBD_EVENT_FLAGS.KEYEVENTF_KEYUP;

                            PInvoke.SendInput(input, Marshal.SizeOf<INPUT>());

i installed cswin32 package and i used send input so code doesnt have red lines but it doesnt work

ero•17mo ago

what's your program's purpose?

어부지망생•17mo ago

ah my program is to control my computer remotely

ero•17mo ago

that's not how you call SendInput anyway https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-sendinput

어부지망생•17mo ago

lot of red lines

ero•17mo ago

that's what happens when you don't think for yourself and just copy and paste that array declaration is obviously not valid c# syntax

Denis•17mo ago

that is because of INPUT inputs[4] = {}, that is syntactically incorrect c# INPUT[] inputs = new INPUT[4]; That is the correct way to declare an empty array in C#

어부지망생•17mo ago

yhea so i tried inputs = new INPUT[4]; first, but it doesnt work

Denis•17mo ago

In what way doesn't it work?

어부지망생•17mo ago

yep

var input = new INPUT[2];

                            input[0].type = INPUT_TYPE.INPUT_KEYBOARD;
                            input[0].Anonymous.ki.wVk = VIRTUAL_KEY.VK_MEDIA_NEXT_TRACK;

                            input[1].type = INPUT_TYPE.INPUT_KEYBOARD;
                            input[1].Anonymous.ki.wVk = VIRTUAL_KEY.VK_MEDIA_NEXT_TRACK;
                            input[1].Anonymous.ki.dwFlags = KEYBD_EVENT_FLAGS.KEYEVENTF_KEYUP;

                            PInvoke.SendInput(input, Marshal.SizeOf<INPUT>());

var input = new INPUT[2];

                            input[0].type = INPUT_TYPE.INPUT_KEYBOARD;
                            input[0].Anonymous.ki.wVk = VIRTUAL_KEY.VK_MEDIA_NEXT_TRACK;

                            input[1].type = INPUT_TYPE.INPUT_KEYBOARD;
                            input[1].Anonymous.ki.wVk = VIRTUAL_KEY.VK_MEDIA_NEXT_TRACK;
                            input[1].Anonymous.ki.dwFlags = KEYBD_EVENT_FLAGS.KEYEVENTF_KEYUP;

                            PInvoke.SendInput(input, Marshal.SizeOf<INPUT>());

this was i tried first

ero•17mo ago

ZeroMemory is probably invalid, SendInput is invalid (without a class that contains it), ARRAYSIZE is invalid

어부지망생•17mo ago

ah..

ero•17mo ago

just think about it a bit before you use it

어부지망생•17mo ago

okok

ero•17mo ago

it's PInvoke.SendInput(input.Length, input, Marshal.SizeOf<INPUT>());

어부지망생•17mo ago

actually i didn't understand this message could you tell me more specific?

ero•17mo ago

can you say exactly what you don't understand?

어부지망생•17mo ago

i didnt understand "without a class that contains it"

ero•17mo ago

SendInput doesn't just exist on its own it's in the class PInvoke

어부지망생•17mo ago

ah thanks i understand what u means

어부지망생•17mo ago

i thinked why it has redline but i cannot find solution..

Denis•17mo ago

When you hover over the red line, what error message do you see?

어부지망생•17mo ago

Compiler Error CS1503 it says cannot change int to uint

Denis•17mo ago

what do you think that means? Not to be annoying, but you need to learn to read and fix error messages

어부지망생•17mo ago

i have to change int to uint?

Denis•17mo ago

exactly

어부지망생•17mo ago

yhea exactly what i need but i didn't know how to change int to uint

Denis•17mo ago

ah, to do that use casting

ero•17mo ago

nevermind, the first declaration works

어부지망생•17mo ago

casting? ok i'll try it and come back

Denis•17mo ago

you can cast a type using the following syntax: (uint)myIntValue

ero•17mo ago

this should actually just work. cswin32 generates an overload that takes a Span, and calls the overload with 3 parameters

Denis•17mo ago

I think you might have to elaborate on that...

ero•17mo ago

what's there to elaborate on

Denis•17mo ago

I'm not sure whether @어부지망생 will know what is and how to use a Span given that casting is a new concept for them

ero•17mo ago

all that matters is that it should work the rest is irrelevant

어부지망생•17mo ago

what is span?

Denis•17mo ago

Given your previous attempts at creating an array, do you happen to have experience with C++?

ero•17mo ago

they didn't "attempt" it they copied it from the doc page https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-sendinput#example

어부지망생•17mo ago

okok calm down sry 😦 i have experienced with c# java python not with c++

Denis•17mo ago

Ok. Asking to get a perspective on how to explain span to you Not really sure how to do that in simple terms 😄

ero•17mo ago

it's an array that's really all you need to know at your level anyway anything else will overwhelm you Span and array are implicitly convertible even so the call they do here is completely valid

Denis•17mo ago

But don't hold on to that, as a span is much more than that. Just like @Ero says, view it as a collection of items, an array for now

ero•17mo ago

it likely doesn't work because of the project type (windows service)

어부지망생•17mo ago

ok 😄 so is there any way to solve this problem?

ero•17mo ago

no clue

어부지망생•17mo ago

And just wondering are u working on it industry? Like softwafe developer? Ah... what should i do...

Denis•17mo ago

So to clarify: - you have a windows service project - you want it to access th current Windows desktop and - type something into, e.g., notepad?

어부지망생•17mo ago

Nono i want to control media like play pause music

Denis•17mo ago

And by Service you literally mean a Windows service running in the background, or a Console/WinForms/WPF... application?

어부지망생•17mo ago

I meam service running in background

Accord•17mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Allow service to interact with desktop