C# how to use WM_GETTEXT / GetWindowText API / Window Title

C# how to use WM_GETTEXT / GetWindowText API / Window Title

In C#, you can use the SendMessage function from the user32.dll library to send the WM_GETTEXT message to retrieve the text of a window, or you can use the GetWindowText function directly from user32.dll. Both methods allow you to get the window title (text) of a specific window identified by its handle.

Here's how you can use either approach:

Using SendMessage (WM_GETTEXT):

using System; using System.Runtime.InteropServices; class Program { private const int WM_GETTEXT = 0x000D; private const int WM_GETTEXTLENGTH = 0x000E; [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] private static extern IntPtr SendMessage(IntPtr hWnd, int msg, int wParam, [MarshalAs(UnmanagedType.LPWStr)] System.Text.StringBuilder lParam); [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] private static extern int SendMessage(IntPtr hWnd, int msg, int wParam, int lParam); static void Main(string[] args) { IntPtr handle = /* Obtain the handle of the window you want to get the title from */; // First, get the length of the window title text int titleLength = SendMessage(handle, WM_GETTEXTLENGTH, 0, 0); // Allocate a StringBuilder to receive the window title System.Text.StringBuilder title = new System.Text.StringBuilder(titleLength + 1); // Now, get the window title text SendMessage(handle, WM_GETTEXT, title.Capacity, title); Console.WriteLine("Window Title: " + title.ToString()); } }

Using GetWindowText directly:

using System; using System.Runtime.InteropServices; class Program { [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] private static extern int GetWindowText(IntPtr hWnd, System.Text.StringBuilder lpString, int nMaxCount); [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] private static extern int GetWindowTextLength(IntPtr hWnd); static void Main(string[] args) { IntPtr handle = /* Obtain the handle of the window you want to get the title from */; // First, get the length of the window title text int titleLength = GetWindowTextLength(handle); // Allocate a StringBuilder to receive the window title System.Text.StringBuilder title = new System.Text.StringBuilder(titleLength + 1); // Now, get the window title text GetWindowText(handle, title, title.Capacity); Console.WriteLine("Window Title: " + title.ToString()); } }

In both approaches, you need to replace /* Obtain the handle of the window you want to get the title from */ with the actual handle of the window whose title you want to retrieve. You can obtain a window handle using methods like FindWindow or EnumWindows, depending on your use case.

Remember that both methods can only retrieve the window title of visible windows. Hidden or minimized windows won't have a valid window title. Additionally, ensure that you are running the code with appropriate privileges to access the window's information.

Examples

  1. "C# WM_GETTEXT example"

    • Description: Learn how to use the WM_GETTEXT message in C# to retrieve text from a window.
    // Code Implementation [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] public static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, StringBuilder lParam); // Usage StringBuilder windowText = new StringBuilder(256); SendMessage(hWnd, WM_GETTEXT, windowText.Capacity, windowText);

  2. "C# GetWindowText API tutorial"

    • Description: A step-by-step tutorial on using the GetWindowText API in C# to obtain the text of a window.
    // Code Implementation [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] public static extern int GetWindowText(IntPtr hWnd, StringBuilder lpString, int nMaxCount); // Usage StringBuilder windowText = new StringBuilder(256); GetWindowText(hWnd, windowText, windowText.Capacity);

  3. "C# get window title from handle"

    • Description: How to retrieve the title of a window using the window handle in C#.
    // Code Implementation StringBuilder windowTitle = new StringBuilder(256); GetWindowText(hWnd, windowTitle, windowTitle.Capacity);

  4. "C# read window text from handle"

    • Description: Reading text from a window handle in C# using various methods including WM_GETTEXT and GetWindowText.
    // Code Implementation StringBuilder windowText = new StringBuilder(256); SendMessage(hWnd, WM_GETTEXT, windowText.Capacity, windowText);

  5. "C# get window text from process"

    • Description: Extracting window text in C# based on the process information.
    // Code Implementation Process process = Process.GetProcessesByName("ProcessName")[0]; IntPtr hWnd = process.MainWindowHandle; StringBuilder windowText = new StringBuilder(256); GetWindowText(hWnd, windowText, windowText.Capacity);

  6. "C# WM_GETTEXT vs GetWindowText difference"

    • Description: Understanding the differences between WM_GETTEXT and GetWindowText in C# and when to use each.
    // Code Implementation (WM_GETTEXT) SendMessage(hWnd, WM_GETTEXT, windowText.Capacity, windowText); // Code Implementation (GetWindowText) GetWindowText(hWnd, windowText, windowText.Capacity);

  7. "C# capture window title change event"

    • Description: How to capture and handle events when the title of a window changes in C#.
    // Code Implementation // Set up a Windows Hook to monitor title changes

  8. "C# enumerate windows and get text"

    • Description: Enumerating all windows in C# and extracting text from each window.
    // Code Implementation EnumWindows(EnumWindowsProc, 0); // EnumWindowsProc would contain logic to get window text for each window

  9. "C# find window by title"

    • Description: Locating a window in C# based on its title.
    // Code Implementation IntPtr hWnd = FindWindow(null, "Window Title");

  10. "C# handle multiple windows text retrieval"

    • Description: Managing and retrieving text from multiple windows in C# using WM_GETTEXT and GetWindowText.
    // Code Implementation foreach (IntPtr hWnd in GetOpenWindows()) { StringBuilder windowText = new StringBuilder(256); SendMessage(hWnd, WM_GETTEXT, windowText.Capacity, windowText); // Handle each window text as needed }

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