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PostMessage only works during first ~110ms of application lifetime

I'm trying to send Ctrl+Up to a non-active Spotify window. Although this isn't a reliable method for every app, a PostMessage using WM_KEYDOWN / WM_KEYUP does work... but only if it's the very first thing my program does. After my own program has been running for more than 120 milliseconds, nothing happens.
With the repro below, Spotify does nothing in response.
If I remove the Thread.Sleep call at the top of the program, or lower its value below 100, then Spotify does change its volume in response to the simulated input.
With values between 100 and 120, then it sometimes works and sometimes doesn't.
What the heck is going on and how can I fix it?
Here's the self-contained repro:
using System;
using System.Linq;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Threading;
class Program {
static void Main(string[] args) {
// 0-100: Works reliably
// 101-119: Works some of the time
// 120+: Never works
Thread.Sleep(120);
var hWnd = Process.GetProcessesByName("spotify").Select(x => x.MainWindowHandle).FirstOrDefault(x => x != IntPtr.Zero);
PostMessage(hWnd, WM_KEYDOWN, VK_CONTROL, 0);
PostMessage(hWnd, WM_KEYDOWN, VK_UP, 0);
Thread.Sleep(1);
PostMessage(hWnd, WM_KEYUP, VK_UP, 0);
PostMessage(hWnd, WM_KEYUP, VK_CONTROL, 0);
}
public static readonly int WM_KEYDOWN = 0x100;
public static readonly int WM_KEYUP = 0x101;
public static readonly int WM_CHAR = 0x102;
public static readonly int VK_CONTROL = 0x11;
public static readonly int VK_UP = 0x26;
public static readonly int VK_DOWN = 0x28;
[DllImport("user32.DLL", EntryPoint = "PostMessage")]
public static extern IntPtr PostMessage(IntPtr hWnd, int msg, int wParam, uint lParam);
}
Other observations:
PostMessage always returns 1
The hWnd value is consistently correct
I can send multiple rounds of Ctrl-Up during the "opening window" - putting the 4 PostMessage calls inside a for loop will correctly increment the volume multiple times
Repro is a Console App but I also see the behavior in a WinForms application

Set System Volume Windows 10 in C# [duplicate]

This question already has answers here:
How to programmatically set the system volume?
(7 answers)
Closed 3 years ago.
i searched like hours, now i ask in this Forum.
How can I control the System Volume Setting of Windows 10?
Which Libary I need?
I am using Visual Basic 2015 and wanna programm a Windows Universal App with C#.
The programm should be able to:
Set Systemvolume to x%
increase the Systemvolume by x
decrease the Systemvolume by x
get the current Systemvolume
I found a similar Question and Answer, but the Answer doesent work.
private void Mute()
{
SendMessageW(new WindowInteropHelper(this).Handle, WM_APPCOMMAND, new WindowInteropHelper(this).Handle,
(IntPtr)APPCOMMAND_VOLUME_MUTE);
}
it can't find "WindowInteropHelper". But I implement:
using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;

class VolumeChanger
{
private const byte VK_VOLUME_MUTE = 0xAD;
private const byte VK_VOLUME_DOWN = 0xAE;
private const byte VK_VOLUME_UP = 0xAF;
private const UInt32 KEYEVENTF_EXTENDEDKEY = 0x0001;
private const UInt32 KEYEVENTF_KEYUP = 0x0002;
[DllImport("user32.dll")]
static extern void keybd_event(byte bVk, byte bScan, UInt32 dwFlags, UInt32 dwExtraInfo);
[DllImport("user32.dll")]
static extern Byte MapVirtualKey(UInt32 uCode, UInt32 uMapType);
public static void VolumeUp()
{
keybd_event(VK_VOLUME_UP, MapVirtualKey(VK_VOLUME_UP, 0), KEYEVENTF_EXTENDEDKEY, 0);
keybd_event(VK_VOLUME_UP, MapVirtualKey(VK_VOLUME_UP, 0), KEYEVENTF_EXTENDEDKEY | KEYEVENTF_KEYUP, 0);
}
public static void VolumeDown()
{
keybd_event(VK_VOLUME_DOWN, MapVirtualKey(VK_VOLUME_DOWN, 0), KEYEVENTF_EXTENDEDKEY, 0);
keybd_event(VK_VOLUME_DOWN, MapVirtualKey(VK_VOLUME_DOWN, 0), KEYEVENTF_EXTENDEDKEY | KEYEVENTF_KEYUP, 0);
}
public static void Mute()
{
keybd_event(VK_VOLUME_MUTE, MapVirtualKey(VK_VOLUME_MUTE, 0), KEYEVENTF_EXTENDEDKEY, 0);
keybd_event(VK_VOLUME_MUTE, MapVirtualKey(VK_VOLUME_MUTE, 0), KEYEVENTF_EXTENDEDKEY | KEYEVENTF_KEYUP, 0);
}
}
Using this, you can mute, and increase or decrease Systemvolume by 2 degree.
I still searching a way to get the current Systemvolume.

You can't do that. Universal apps are sandboxed and can't make global modifications to the system. This includes the system volume.

I believe there is a way using nircmd.
First download nircmd and attach it to the project:
http://www.nirsoft.net/utils/nircmd.html
Then, call it via cmd:
Run Command Prompt Commands
The commands you want are specified in the nircmd website.
for instance, to change the volume to x% use:
realativePath/nircmd.exe setsysvolume x

Virtual mouse click c#

I have an multithreaded application that needs to be able to preform multiple mouse click at the same time.
I have an IntPtr intptr to a process on which i need to send a mouse click to.
I have tried to find this information on the web and there are some examples which i have tried. But I have not got any of them to work.
As I understand the correct way to solv my issue is to use the function
SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);
hWnd is the IntPtr to the process.
Msg is the wanted action, which I want a left click, int WM_LBUTTONDBLCLK = 0x0203;
IntPtr wParam is of no intrest to this problem ( as I understand)
And the coordinates to the click is in lParam.
I construct lParam like,
Int32 word = MakeLParam(x, y);
private int MakeLParam(int LoWord, int HiWord)
{
return ((HiWord << 16) | (LoWord & 0xffff));
}
But as you might understand, I cant get this to work.
My first question is, the coordinates are they within the window of this process or are
the absolut screen coordinates?
And my second question, what am I doing wrong?

I was trying to simulate mouse clicks in C# just recently, I wrote this little helper class to do the trick:
public static class SimInput
{
[DllImport("user32.dll")]
static extern void mouse_event(uint dwFlags, uint dx, uint dy, uint dwData, UIntPtr dwExtraInfo);
[Flags]
public enum MouseEventFlags : uint
{
Move = 0x0001,
LeftDown = 0x0002,
LeftUp = 0x0004,
RightDown = 0x0008,
RightUp = 0x0010,
MiddleDown = 0x0020,
MiddleUp = 0x0040,
Absolute = 0x8000
}
public static void MouseEvent(MouseEventFlags e, uint x, uint y)
{
mouse_event((uint)e, x, y, 0, UIntPtr.Zero);
}
public static void LeftClick(Point p)
{
LeftClick((double)p.X, (double)p.Y);
}
public static void LeftClick(double x, double y)
{
var scr = Screen.PrimaryScreen.Bounds;
MouseEvent(MouseEventFlags.LeftDown | MouseEventFlags.LeftUp | MouseEventFlags.Move | MouseEventFlags.Absolute,
(uint)Math.Round(x / scr.Width * 65535),
(uint)Math.Round(y / scr.Height * 65535));
}
public static void LeftClick(int x, int y)
{
LeftClick((double)x, (double)y);
}
}
The coordinates are a fraction of 65535, which is a bit odd, but this class will handle that for you.

I'm not 100% sure I understand what you're trying to accomplish. But if you want to simulate mouse input then I'd recommend using the SendInput API.
You can provide an array of inputs to be inserted into the input stream.
See also: PInvoke reference

I don't understand why anyone would want to send multiple mouse clicks simultaneously. If it's to test your GUI, it's the wrong test. No one can physically click something multiple times in the same time space.
But going back to your question, using SendMessage won't help you, because it is basically a blocking call. Even if you tried to use PostMessage, you won't be able to accomplish simultaneous clicks, because the message queue is getting pumped from the UI thread and has messages popped off and handled sequentially.

I used this code to click left button in handle
public static void MouseLeftClick(Point p, int handle = 0)
{
//build coordinates
int coordinates = p.X | (p.Y << 16);
//send left button down
SendMessage(handle, 0x201, 0x1, coordinates);
//send left button up
SendMessage(handle, 0x202, 0x1, coordinates);
}
If you set no handle with calling - then it sends click to Desktop, so coordinates should be for whole screen, if you will set handle, then message will be sent to handle's window and you should set coordinates for window.

How about just using VirtualMouse? I use it in C# and it works great.
public partial class Form1 : Form
{
private VirtualMouse vm = new VirtualMouse();
public Form1()
{
InitializeComponent();
}
private void MouseClickHere(Point myPoint)
{
vm.ClickIt(myPoint, 150);
}
private void Clicker()
{
MouseClickHere(new Point(250,350));
}
}

How to programatically trigger a mouse left click in C#?

How could I programmatically trigger a left-click event on the mouse?
Thanks.
edit: the event is not triggered directly on a button. I'm aiming for the Windows platform.

To perform a mouse click:
[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
public static extern void mouse_event(long dwFlags, long dx, long dy, long cButtons, long dwExtraInfo);
private const int MOUSEEVENTF_LEFTDOWN = 0x02;
private const int MOUSEEVENTF_LEFTUP = 0x04;
private const int MOUSEEVENTF_RIGHTDOWN = 0x08;
private const int MOUSEEVENTF_RIGHTUP = 0x10;
public static void DoMouseClick()
{
mouse_event(MOUSEEVENTF_LEFTDOWN | MOUSEEVENTF_LEFTUP, 0, 0, 0, 0);
}
To move the cursor where you want:
[DllImport("user32.dll")]
static extern bool SetCursorPos(int X, int Y);
public static void MoveCursorToPoint(int x, int y)
{
SetCursorPos(x, y);
}

If it's right on a button, you can use
button1.PerformClick();
Otherwise, you can check out this MSDN article which discusses simulating mouse (and keyboard) input.
Additionally, this project may be able to help you out as well. Under the covers, it uses SendInput.

https://web.archive.org/web/20140214230712/http://www.pinvoke.net/default.aspx/user32.sendinput
Use the Win32 API to send input.
Update:
Since I no longer work with Win32 API, I will not update this answer to be correct when the platform changes or websites become unavailable. Since this answer doesn't even conform to Stackoverflow standards (does not contain the answer itself, but rather a link to an external, now defunct resource), there's no point giving it any points or spending any more time on it.
Instead, take a look at this question on Stackoverflow, which I think is a duplicate:
How to simulate Mouse Click in C#?

Progress Bar in Setup Application

I have created a custom action for my setup project and have successfully implemented a form that displays a progress bar for a download step in my install (I'm using a WebClient in my custom action code). So I have two questions that relate to each other.
Is there any way to show a download progress bar in the main setup window rather than creating a separate form that I display as I have done? I would prefer this.
If not, then what can I do to cause my form to display in front of the actual setup window when I call form.ShowDialog()? I've also called BringToFront() on it which doesn't work either. It's there, but it's always behind the main setup window. Seems there has to be some way to get the correct z-order.
Thanks for your help.

So I gave up on the idea of integrating the progress bar into the actual installer screen, but it's just plain ridiculous what it takes to get the Windows Form to display on top. I have to get a handle to the installer Window and send it to the background because bringing the progress bar window forward simply won't work. I've moved to Mac development now so coming back to this is just frustrating. I remember thinking C# .NET was pretty cool. It's got NOTHING on Cocoa/Objective-C.
It's infuriating having a method called BringToFront() that simply ignores you. Why do I have to drop down to Windows API code to do something as fundamental to a GUI as managing the the Z-Order? Z-Order? Seriously?
In case you're wondering, here's what I ended up doing (via google):
[DllImport("user32.dll", EntryPoint = "SetWindowPos")]
public static extern bool SetWindowPos(
IntPtr hWnd, // window handle
IntPtr hWndInsertAfter, // placement-order handle
int X, // horizontal position
int Y, // vertical position
int cx, // width
int cy, // height
uint uFlags); // window positioning flags
public const uint SWP_NOSIZE = 0x1;
public const uint SWP_NOMOVE = 0x2;
public const uint SWP_SHOWWINDOW = 0x40;
public const uint SWP_NOACTIVATE = 0x10;
[DllImport("user32.dll", EntryPoint = "GetWindow")]
public static extern IntPtr GetWindow(
IntPtr hWnd,
uint wCmd);
public const uint GW_HWNDFIRST = 0;
public const uint GW_HWNDLAST = 1;
public const uint GW_HWNDNEXT = 2;
public const uint GW_HWNDPREV = 3;
public static void ControlSendToBack(IntPtr control)
{
bool s = SetWindowPos(
control,
GetWindow(control, GW_HWNDLAST),
0, 0, 0, 0,
SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
}
I get a handle to the installer window and then call ControlSendToBack() on it. It works, but it sends it to the very back. I tried another method that would just send it back one position, but this wouldn't work either. Windows programming--as good as it was in 1995. Cool.

Another way of doing this is to use a BackgroundWorker. You let the Background Worker handle the downloading of the file so it doesn't prevent the UI being updated.
See this link on donnetperls