Detailed explanation of C# SetWindowPos function example

In C#, the SetWindowPos function is used to set the position and size of the window.

prototype:

[DllImport("", SetLastError = true)]
[return: MarshalAs()]
public static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);

Parameter description:

hWnd: The handle of the window to set the position and size.
hWndInsertAfter: Determines the Z order of the window, that is, how the windows are placed in the Z order. One of the following values can usually be used:
- : Place the window at the top of the Z-order.
- new IntPtr(-1): Place the window at the top of all non-top-level windows.
- new IntPtr(-2): Place the window at the top of all windows.
Other window handles: Place the window at the top of the specified window.
XandY: X and Y coordinates in the upper left corner of the new position of the window.
cxandcy: New width and height of the window.
uFlags: Set the window position and size flag. You can use a combination of the following flags to control the behavior of the window:
- SWP_NOSIZE: Maintain the current size (ignoring the cx and cy parameters).
- SWP_NOMOVE: Maintain the current position (ignore the X and Y parameters).
- SWP_NOZORDER: Maintain the current Z order (ignoring the hWndInsertAfter parameter).
- SWP_SHOWWINDOW: If the window is hidden when called, the window is displayed.
- SWP_HIDEWINDOW: Hide window.
- SWP_NOACTIVATE: The window is not activated. Applicable onlySWP_SHOWWINDOWLogo.
- SWP_DRAWFRAME: When resizing the window, repaint the window border (usually withSWP_FRAMECHANGEDUse together).
- SWP_NOOWNERZORDER: Do not change the Z order of the owner window.
- SWP_NOSENDCHANGING: Prevent window receptionWM_WINDOWPOSCHANGINGinformation.
- SWP_FRAMECHANGED: Make the system sendWM_NCCALCSIZEMessage, even if the window size has not changed.
- SWP_NOCOPYBITS: Prevent windows from redrawing.
- SWP_NOREPOSITION: The window is not repositioned even if the size or position changes.

Example usage:

1. Change the window size:

using System;
using ;
// Define constants and method signaturespublic class Win32
{
    [DllImport("")]
    public static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
    public static readonly IntPtr HWND_TOPMOST = new IntPtr(-1);
    public const uint SWP_SHOWWINDOW = 0x40;
}
// Get the window handle and call the SetWindowPos function to change the window sizeIntPtr hWnd = // Window handleint newX = // New X coordinatesint newY = // New Y coordinatesint newWidth = // New widthint newHeight = // New heights(hWnd, Win32.HWND_TOPMOST, newX, newY, newWidth, newHeight, Win32.SWP_SHOWWINDOW);

The window handle can be used to obtain the window handle (same as follows), such as:

[DllImport("", SetLastError = true)]
    public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
    IntPtr hWnd = (null, "Window Title"); // Replace the class name or title of the window

2. Move to the upper left corner of the screen:

using System;
using ;
// Define constants and method signaturespublic class Win32
{
    public const int SWP_NOSIZE = 0x0001;
    public const int SWP_NOMOVE = 0x0002;
    public const int SWP_NOZORDER = 0x0004;
    public const int SWP_SHOWWINDOW = 0x0040;
    [DllImport("", SetLastError = true)]
    [return: MarshalAs()]
    public static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
}
// Call SetWindowPos function in the code to move the window to the upper left corner of the screenIntPtr hWnd = // Window handle(hWnd, , 0, 0, 0, 0, Win32.SWP_NOSIZE | Win32.SWP_SHOWWINDOW);

3. Make it a Topmost window and move it to the upper left corner of the screen:

using System;
using ;
// Define constants and method signaturespublic class Win32
{
    public const int SWP_NOSIZE = 0x0001;
    public const int SWP_NOMOVE = 0x0002;
    public const int SWP_NOZORDER = 0x0004;
    public const int SWP_SHOWWINDOW = 0x0040;
    public const int HWND_TOPMOST = -1;
    public const int HWND_NOTOPMOST = -2;
    [DllImport("", SetLastError = true)]
    [return: MarshalAs()]
    public static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
}
// Call the SetWindowPos function in the code to move the window to the upper left corner of the screen and set it to TopmostIntPtr hWnd = // Window handle(hWnd, Win32.HWND_TOPMOST, 0, 0, 0, 0, Win32.SWP_NOSIZE | Win32.SWP_SHOWWINDOW);

4. Display window:

using System;
using ;
// Define constants and method signaturespublic class Win32
{
    public const int SW_SHOWNORMAL = 1;
    [DllImport("")]
    public static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
}
// Get the window handle and call the ShowWindow function to display the windowIntPtr hWnd = // Window handle(hWnd, Win32.SW_SHOWNORMAL);

5. Hide window:

using System;
using ;
// Define constants and method signaturespublic class Win32
{
    public const int SW_HIDE = 0;
    [DllImport("")]
    public static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
}
// Get the window handle and call the ShowWindow function to hide the windowIntPtr hWnd = // Window handle(hWnd, Win32.SW_HIDE);

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