whitemagic/WhiteMagic/Windows/RemoteWindow.cs

using System.Runtime.InteropServices;
using System.Text;
using WhiteMagic.Native;

namespace WhiteMagic.Windows;

/// <summary>
/// Wrapper around a native window handle that supports querying and mutating
/// common window properties.
/// </summary>
public sealed class RemoteWindow
{
    private const int MaxTextLength = 512;

    /// <summary>Creates a wrapper for the specified window handle.</summary>
    public RemoteWindow(IntPtr handle)
    {
        if (handle == IntPtr.Zero)
            throw new ArgumentException("Window handle cannot be zero.", nameof(handle));

        Handle = handle;
    }

    /// <summary>The native window handle.</summary>
    public IntPtr Handle { get; }

    /// <summary>The window class name.</summary>
    public string ClassName => GetClassName(Handle);

    /// <summary>The current window text.</summary>
    public string Text => GetWindowText(Handle);

    /// <summary>The process identifier that owns the window.</summary>
    public uint ProcessId => GetWindowProcessId(Handle);

    /// <summary>Gets or sets the window title.</summary>
    public string Title
    {
        get => GetWindowText(Handle);
        set
        {
            if (value is null)
                throw new ArgumentNullException(nameof(value));

            if (!NativeMethods.SetWindowTextW(Handle, value))
            {
                int error = Marshal.GetLastPInvokeError();
                throw new InvalidOperationException(
                    $"SetWindowText failed for window {Handle} with error {error}.");
            }
        }
    }

    /// <summary><see langword="true"/> if this window is currently the foreground window.</summary>
    public bool IsActive => NativeMethods.GetForegroundWindow() == Handle;

    /// <summary>Moves and resizes the window.</summary>
    public bool MoveResize(int x, int y, int width, int height)
    {
        return NativeMethods.SetWindowPos(
            Handle,
            NativeMethods.HwndTop,
            x,
            y,
            width,
            height,
            NativeMethods.SwpShowWindow);
    }

    /// <summary>Activates the window and brings it to the foreground.</summary>
    public bool Activate()
    {
        IntPtr foreground = NativeMethods.GetForegroundWindow();
        uint targetThread = NativeMethods.GetWindowThreadProcessId(Handle, out _);

        if (targetThread == 0)
            return false;

        // If there's no foreground window, or we're already in the foreground thread, just set it
        if (foreground == IntPtr.Zero)
            return NativeMethods.SetForegroundWindow(Handle);

        uint foregroundThread = NativeMethods.GetWindowThreadProcessId(foreground, out _);

        if (targetThread == foregroundThread)
            return NativeMethods.SetForegroundWindow(Handle);

        if (!NativeMethods.AttachThreadInput(foregroundThread, targetThread, true))
            return false;

        try
        {
            return NativeMethods.SetForegroundWindow(Handle);
        }
        finally
        {
            NativeMethods.AttachThreadInput(foregroundThread, targetThread, false);
        }
    }

    /// <summary>Flashes the window in the caption and taskbar button.</summary>
    public bool Flash()
    {
        var info = new FlashWindowInfo
        {
            cbSize = (uint)Marshal.SizeOf<FlashWindowInfo>(),
            hwnd = Handle,
            dwFlags = NativeMethods.FlashwAll,
            uCount = 3,
            dwTimeout = 0,
        };

        return NativeMethods.FlashWindowEx(ref info);
    }

    public override string ToString()
    {
        var sb = new StringBuilder();
        sb.Append("RemoteWindow(");
        sb.Append(Handle.ToString("X"));
        sb.Append(", ");
        sb.Append(ClassName);
        sb.Append(")");
        return sb.ToString();
    }

    private static string GetClassName(IntPtr handle)
    {
        var buffer = new char[256];
        int length = NativeMethods.GetClassNameW(handle, buffer, buffer.Length);
        if (length <= 0)
            return string.Empty;

        return new string(buffer, 0, length);
    }

    private static string GetWindowText(IntPtr handle)
    {
        var buffer = new char[MaxTextLength];
        int length = NativeMethods.GetWindowTextW(handle, buffer, buffer.Length);
        if (length <= 0)
            return string.Empty;

        return new string(buffer, 0, length);
    }

    private static uint GetWindowProcessId(IntPtr handle)
    {
        NativeMethods.GetWindowThreadProcessId(handle, out uint processId);
        return processId;
    }
}