mirror of https://github.com/dahall/Vanara.git
117 lines
3.8 KiB
C#
117 lines
3.8 KiB
C#
using System;
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using static Vanara.PInvoke.User32;
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namespace Vanara.PInvoke;
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/// <summary>Delegate for a method that processes a <see cref="MSG"/> structure.</summary>
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/// <param name="msg">The <see cref="MSG"/> structure to process.</param>
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public delegate void MsgPumpDelegate(ref MSG msg);
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/// <summary>
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/// Delegate for a method that processes a <see cref="MSG"/> structure and returns a value determining if the next step should be processed.
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/// </summary>
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/// <param name="msg">The <see cref="MSG"/> structure to process.</param>
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/// <returns><see langword="true"/> if the pump should proceed; otherwise <see langword="false"/>.</returns>
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public delegate bool MsgPumpPredicateDelegate(ref MSG msg);
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/// <summary>Interface defining a message pump.</summary>
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public interface IMessagePump
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{
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/// <summary>Runs the message pump on the optionally specified window.</summary>
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/// <param name="mainWindow">The window instance.</param>
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/// <returns>
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/// The result of <see cref="PeekMessage(out MSG, HWND, uint, uint, PM)"/> or <see cref="GetMessage(out MSG, HWND, uint, uint)"/>.
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/// </returns>
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int Run(IWindowInstance mainWindow = null);
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}
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/// <summary>An interface that represents a Win32 window with created and destroyed events.</summary>
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public interface IWindowInstance
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{
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/// <summary>Occurs when the window has been destroyed.</summary>
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event Action Destroyed;
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/// <summary>Gets the window handle.</summary>
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/// <value>The window handle.</value>
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HWND Handle { get; }
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}
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/// <summary>A basic message pump to use independently or with a window instance.</summary>
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/// <example>
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/// Simple example of a window creation and message pump.
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/// <code>using (var win = new BasicMessageWindow() { Text = "Title", Visible = true })
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/// return new MessagePump().Run(win);</code></example>
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/// <seealso cref="IMessagePump" />
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public class MessagePump : IMessagePump
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{
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/// <summary>Easy access to WM_QUIT value.</summary>
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protected const ushort quitMsg = (ushort)WindowMessage.WM_QUIT;
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/// <inhertdoc/>
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public int Run(IWindowInstance mainWindow = null)
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{
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if (mainWindow is not null and not WindowBase)
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mainWindow.Destroyed += onDestroy;
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try
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{
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return RunLoop();
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}
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finally
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{
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if (mainWindow is not null and not WindowBase)
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mainWindow.Destroyed -= onDestroy;
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}
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static void onDestroy() => PostQuitMessage(0);
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}
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/// <summary>Defines and executes the message pump.</summary>
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/// <returns>
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/// The result of <see cref="PeekMessage(out MSG, HWND, uint, uint, PM)"/> or <see cref="GetMessage(out MSG, HWND, uint, uint)"/>.
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/// </returns>
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protected virtual int RunLoop()
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{
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int bRet;
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while ((bRet = GetMessage(out MSG msg)) != 0)
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{
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if (bRet == -1)
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Win32Error.ThrowLastError();
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TranslateMessage(msg);
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DispatchMessage(msg);
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}
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return bRet;
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}
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}
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/// <summary>A message pump with events to process each step to use independently or with a window instance.</summary>
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/// <seealso cref="MessagePump"/>
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public class ExaminedMessagePump : MessagePump
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{
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/// <summary>Occurs after <see cref="DispatchMessage(in MSG)"/>.</summary>
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public event MsgPumpDelegate PostProcess;
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/// <summary>Occurs after <see cref="TranslateMessage(in MSG)"/> and determines if message should be dispatched.</summary>
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public event MsgPumpPredicateDelegate PostTranslate;
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/// <summary>
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/// Occurs after <see cref="PeekMessage(out MSG, HWND, uint, uint, PM)"/> and determines if message should be translated or dispatched.
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/// </summary>
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public event MsgPumpPredicateDelegate PreProcess;
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/// <inhertdoc/>
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protected override int RunLoop()
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{
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MSG msg;
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do
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{
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if (PeekMessage(out msg, default, 0, 0, PM.PM_REMOVE) && (PreProcess?.Invoke(ref msg) ?? true))
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{
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TranslateMessage(msg);
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if (PostTranslate?.Invoke(ref msg) ?? true)
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DispatchMessage(msg);
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PostProcess?.Invoke(ref msg);
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}
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} while (Macros.LOWORD(msg.message) != quitMsg);
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return 0;
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}
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} |