mirror of https://github.com/dahall/Vanara.git
106 lines
4.2 KiB
C#
106 lines
4.2 KiB
C#
using System;
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using System.Runtime.InteropServices;
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using static Vanara.PInvoke.Kernel32;
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using static Vanara.PInvoke.User32;
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namespace Vanara.PInvoke
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{
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/// <summary>A filter method that handles messages sent to a window.</summary>
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/// <param name="hwnd">A handle to the window.</param>
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/// <param name="msg">The MSG.</param>
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/// <param name="wParam">Additional message information. The contents of this parameter depend on the value of the uMsg parameter.</param>
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/// <param name="lParam">Additional message information. The contents of this parameter depend on the value of the uMsg parameter.</param>
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/// <param name="lReturn">The return value is the result of the message processing and depends on the message sent.</param>
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/// <returns>
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/// <see langword="true"/> if the message is handled and <see cref="DefWindowProc(HWND, uint, IntPtr, IntPtr)"/> should not be called;
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/// <see langword="false"/> otherwise.
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/// </returns>
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[UnmanagedFunctionPointer(CallingConvention.Winapi)]
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public delegate bool BasicMessageWindowFilter(HWND hwnd, uint msg, IntPtr wParam, IntPtr lParam, out IntPtr lReturn);
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/// <summary>Simple window to process messages.</summary>
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/// <seealso cref="MarshalByRefObject"/>
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/// <seealso cref="IDisposable"/>
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/// <seealso cref="IHandle"/>
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public class BasicMessageWindow : MarshalByRefObject, IDisposable, IHandle
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{
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private readonly WeakReference weakSelfRef;
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private SafeHWND hwnd;
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private bool isDisposed;
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private WindowClass wCls;
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/// <summary>Initializes a new instance of the <see cref="BasicMessageWindow"/> class.</summary>
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/// <param name="callback">Specifies the callback method to use to process messages.</param>
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public BasicMessageWindow(BasicMessageWindowFilter callback = null)
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{
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MessageFilter = callback;
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weakSelfRef = new WeakReference(this);
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hwnd = CreateWindow();
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}
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/// <summary>Finalizes an instance of the <see cref="BasicMessageWindow"/> class.</summary>
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~BasicMessageWindow() => Dispose(false);
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/// <summary>Gets the handle.</summary>
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/// <value>The handle.</value>
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public HWND Handle => hwnd ?? HWND.NULL;
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/// <summary>Gets or sets the callback method used to filter window messages.</summary>
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/// <value>The callback method.</value>
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public BasicMessageWindowFilter MessageFilter { get; set; }
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/// <summary>Gets the name of the class.</summary>
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/// <value>The name of the class.</value>
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public string ClassName => wCls?.ClassName;
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/// <summary>Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.</summary>
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public void Dispose()
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{
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Dispose(true);
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System.GC.SuppressFinalize(this);
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}
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/// <summary>Returns the value of the handle field.</summary>
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/// <returns>An IntPtr representing the value of the handle field.</returns>
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IntPtr IHandle.DangerousGetHandle() => (IntPtr)Handle;
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/// <summary>
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/// Method used to create the window. When overriding, the <c>hWnd</c> field must be set to the handle of the created window.
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/// </summary>
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protected virtual SafeHWND CreateWindow()
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{
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lock (this)
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{
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if (!Handle.IsNull)
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throw new InvalidOperationException("Window handle already exists.");
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HINSTANCE hInst = GetModuleHandle();
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wCls = new WindowClass($"{GetType().Name}+{Guid.NewGuid()}", hInst, WndProc);
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return Win32Error.ThrowLastErrorIfInvalid(CreateWindowEx(0, wCls.Atom, hWndParent: HWND.HWND_MESSAGE, hInstance: hInst));
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}
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}
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/// <summary>Releases unmanaged and - optionally - managed resources.</summary>
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/// <param name="disposing">
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/// <see langword="true"/> to release both managed and unmanaged resources; <see langword="false"/> to release only unmanaged resources.
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/// </param>
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protected virtual void Dispose(bool disposing)
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{
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if (isDisposed)
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return;
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isDisposed = true;
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hwnd?.Dispose(); // Calls DestroyWindow
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hwnd = null;
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wCls?.Unregister();
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}
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private IntPtr WndProc(HWND hwnd, uint msg, IntPtr wParam, IntPtr lParam)
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{
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if (msg == (uint)WindowMessage.WM_NCCREATE)
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return (IntPtr)1;
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return !weakSelfRef.IsAlive || weakSelfRef.Target is null || MessageFilter is null || !MessageFilter.Invoke(hwnd, msg, wParam, lParam, out IntPtr lRet)
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? DefWindowProc(hwnd, msg, wParam, lParam)
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: lRet;
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}
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}
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} |