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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Windows.Forms.Primitives;
namespace System.Windows.Forms;
/// <summary>
/// Displays a message box that can contain text, buttons, and symbols that inform and instruct the user.
/// </summary>
public class MessageBox
{
[ThreadStatic]
private static HelpInfo[]? t_helpInfoTable;
// This is meant to be a static class, but predates that feature.
private MessageBox()
{
}
internal static HelpInfo? HelpInfo
{
get
{
// Unfortunately, there's no easy way to obtain handle of a message box.
// We'll have to rely on the fact that modal message loops have to pop off in an orderly way.
if (t_helpInfoTable is not null && t_helpInfoTable.Length > 0)
{
// The top of the stack is actually at the end of the array.
return t_helpInfoTable[^1];
}
return null;
}
}
private static MESSAGEBOX_STYLE GetMessageBoxStyle(
IWin32Window? owner,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton,
MessageBoxOptions options,
bool showHelp)
{
SourceGenerated.EnumValidator.Validate(buttons, nameof(buttons));
SourceGenerated.EnumValidator.Validate(icon, nameof(icon));
SourceGenerated.EnumValidator.Validate(defaultButton, nameof(defaultButton));
// options intentionally not verified because we don't expose all the options Win32 supports.
if (!SystemInformation.UserInteractive && (options & (MessageBoxOptions.ServiceNotification | MessageBoxOptions.DefaultDesktopOnly)) == 0)
{
throw new InvalidOperationException(SR.CantShowModalOnNonInteractive);
}
if (owner is not null && (options & (MessageBoxOptions.ServiceNotification | MessageBoxOptions.DefaultDesktopOnly)) != 0)
{
throw new ArgumentException(SR.CantShowMBServiceWithOwner, nameof(options));
}
if (showHelp && (options & (MessageBoxOptions.ServiceNotification | MessageBoxOptions.DefaultDesktopOnly)) != 0)
{
throw new ArgumentException(SR.CantShowMBServiceWithHelp, nameof(options));
}
MESSAGEBOX_STYLE style = (showHelp) ? MESSAGEBOX_STYLE.MB_HELP : 0;
style |= (MESSAGEBOX_STYLE)buttons | (MESSAGEBOX_STYLE)icon | (MESSAGEBOX_STYLE)defaultButton | (MESSAGEBOX_STYLE)options;
return style;
}
private static void PopHelpInfo()
{
// we roll our own stack here because we want a pretty lightweight implementation.
// usually there's only going to be one message box shown at a time. But if
// someone shows two message boxes (say by launching them via a WM_TIMER message)
// we've got to gracefully handle the current help info.
if (t_helpInfoTable is null)
{
Debug.Fail("Why are we being called when there's nothing to pop?");
}
else
{
if (t_helpInfoTable.Length == 1)
{
t_helpInfoTable = null;
}
else
{
int newCount = t_helpInfoTable.Length - 1;
HelpInfo[] newTable = new HelpInfo[newCount];
Array.Copy(t_helpInfoTable, newTable, newCount);
t_helpInfoTable = newTable;
}
}
}
private static void PushHelpInfo(HelpInfo hpi)
{
// we roll our own stack here because we want a pretty lightweight implementation.
// usually there's only going to be one message box shown at a time. But if
// someone shows two message boxes (say by launching them via a WM_TIMER message)
// we've got to gracefully handle the current help info.
int lastCount = 0;
HelpInfo[] newTable;
if (t_helpInfoTable is null)
{
newTable = new HelpInfo[lastCount + 1];
}
else
{
// if we already have a table - allocate a new slot
lastCount = t_helpInfoTable.Length;
newTable = new HelpInfo[lastCount + 1];
Array.Copy(t_helpInfoTable, newTable, lastCount);
}
newTable[lastCount] = hpi;
t_helpInfoTable = newTable;
}
/// <summary>
/// Displays a message box with specified text, caption, and style with Help Button.
/// </summary>
public static DialogResult Show(
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton,
MessageBoxOptions options,
bool displayHelpButton)
{
return ShowCore(null, text, caption, buttons, icon, defaultButton, options, displayHelpButton);
}
/// <summary>
/// Displays a message box with specified text, caption, style and Help file Path .
/// </summary>
public static DialogResult Show(
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton,
MessageBoxOptions options,
string helpFilePath)
{
HelpInfo hpi = new(helpFilePath);
return ShowCore(null, text, caption, buttons, icon, defaultButton, options, hpi);
}
/// <summary>
/// Displays a message box with specified text, caption, style and Help file Path for a IWin32Window.
/// </summary>
public static DialogResult Show(
IWin32Window? owner,
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton,
MessageBoxOptions options,
string helpFilePath)
{
HelpInfo hpi = new(helpFilePath);
return ShowCore(owner, text, caption, buttons, icon, defaultButton, options, hpi);
}
/// <summary>
/// Displays a message box with specified text, caption, style, Help file Path and keyword.
/// </summary>
public static DialogResult Show(
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton,
MessageBoxOptions options,
string helpFilePath,
string keyword)
{
HelpInfo hpi = new(helpFilePath, keyword);
return ShowCore(null, text, caption, buttons, icon, defaultButton, options, hpi);
}
/// <summary>
/// Displays a message box with specified text, caption, style, Help file Path and keyword for a IWin32Window.
/// </summary>
public static DialogResult Show(
IWin32Window? owner,
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton,
MessageBoxOptions options,
string helpFilePath,
string keyword)
{
HelpInfo hpi = new(helpFilePath, keyword);
return ShowCore(owner, text, caption, buttons, icon, defaultButton, options, hpi);
}
/// <summary>
/// Displays a message box with specified text, caption, style, Help file Path and HelpNavigator.
/// </summary>
public static DialogResult Show(
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton,
MessageBoxOptions options,
string helpFilePath,
HelpNavigator navigator)
{
HelpInfo hpi = new(helpFilePath, navigator);
return ShowCore(null, text, caption, buttons, icon, defaultButton, options, hpi);
}
/// <summary>
/// Displays a message box with specified text, caption, style, Help file Path and HelpNavigator for IWin32Window.
/// </summary>
public static DialogResult Show(
IWin32Window? owner,
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton,
MessageBoxOptions options,
string helpFilePath,
HelpNavigator navigator)
{
HelpInfo hpi = new(helpFilePath, navigator);
return ShowCore(owner, text, caption, buttons, icon, defaultButton, options, hpi);
}
/// <summary>
/// Displays a message box with specified text, caption, style, Help file Path ,HelpNavigator and object.
/// </summary>
public static DialogResult Show(
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton,
MessageBoxOptions options,
string helpFilePath,
HelpNavigator navigator,
object? param)
{
HelpInfo hpi = new(helpFilePath, navigator, param);
return ShowCore(null, text, caption, buttons, icon, defaultButton, options, hpi);
}
/// <summary>
/// Displays a message box with specified text, caption, style, Help file Path ,HelpNavigator and object for a IWin32Window.
/// </summary>
public static DialogResult Show(
IWin32Window? owner,
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton,
MessageBoxOptions options,
string helpFilePath,
HelpNavigator navigator,
object? param)
{
HelpInfo hpi = new(helpFilePath, navigator, param);
return ShowCore(owner, text, caption, buttons, icon, defaultButton, options, hpi);
}
/// <summary>
/// Displays a message box with specified text, caption, and style.
/// </summary>
public static DialogResult Show(
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton,
MessageBoxOptions options)
{
return ShowCore(null, text, caption, buttons, icon, defaultButton, options, false);
}
/// <summary>
/// Displays a message box with specified text, caption, and style.
/// </summary>
public static DialogResult Show(
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton)
{
return ShowCore(null, text, caption, buttons, icon, defaultButton, 0, false);
}
/// <summary>
/// Displays a message box with specified text, caption, and style.
/// </summary>
public static DialogResult Show(
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon)
{
return ShowCore(null, text, caption, buttons, icon, MessageBoxDefaultButton.Button1, 0, false);
}
/// <summary>
/// Displays a message box with specified text, caption, and style.
/// </summary>
public static DialogResult Show(string? text, string? caption, MessageBoxButtons buttons)
{
return ShowCore(null, text, caption, buttons, MessageBoxIcon.None, MessageBoxDefaultButton.Button1, 0, false);
}
/// <summary>
/// Displays a message box with specified text and caption.
/// </summary>
public static DialogResult Show(string? text, string? caption)
{
return ShowCore(null, text, caption, MessageBoxButtons.OK, MessageBoxIcon.None, MessageBoxDefaultButton.Button1, 0, false);
}
/// <summary>
/// Displays a message box with specified text.
/// </summary>
public static DialogResult Show(string? text)
{
return ShowCore(null, text, string.Empty, MessageBoxButtons.OK, MessageBoxIcon.None, MessageBoxDefaultButton.Button1, 0, false);
}
/// <summary>
/// Displays a message box with specified text, caption, and style.
/// </summary>
public static DialogResult Show(
IWin32Window? owner,
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton,
MessageBoxOptions options)
{
return ShowCore(owner, text, caption, buttons, icon, defaultButton, options, false);
}
/// <summary>
/// Displays a message box with specified text, caption, and style.
/// </summary>
public static DialogResult Show(
IWin32Window? owner,
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton)
{
return ShowCore(owner, text, caption, buttons, icon, defaultButton, 0, false);
}
/// <summary>
/// Displays a message box with specified text, caption, and style.
/// </summary>
public static DialogResult Show(
IWin32Window? owner,
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon)
{
return ShowCore(owner, text, caption, buttons, icon, MessageBoxDefaultButton.Button1, 0, false);
}
/// <summary>
/// Displays a message box with specified text, caption, and style.
/// </summary>
public static DialogResult Show(
IWin32Window? owner,
string? text,
string? caption,
MessageBoxButtons buttons)
{
return ShowCore(owner, text, caption, buttons, MessageBoxIcon.None, MessageBoxDefaultButton.Button1, 0, false);
}
/// <summary>
/// Displays a message box with specified text and caption.
/// </summary>
public static DialogResult Show(IWin32Window? owner, string? text, string? caption)
{
return ShowCore(owner, text, caption, MessageBoxButtons.OK, MessageBoxIcon.None, MessageBoxDefaultButton.Button1, 0, false);
}
/// <summary>
/// Displays a message box with specified text.
/// </summary>
public static DialogResult Show(IWin32Window? owner, string? text)
{
return ShowCore(owner, text, string.Empty, MessageBoxButtons.OK, MessageBoxIcon.None, MessageBoxDefaultButton.Button1, 0, false);
}
private static DialogResult ShowCore(
IWin32Window? owner,
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton,
MessageBoxOptions options,
HelpInfo hpi)
{
DialogResult result = DialogResult.None;
try
{
PushHelpInfo(hpi);
result = ShowCore(owner, text, caption, buttons, icon, defaultButton, options, true);
}
finally
{
PopHelpInfo();
}
return result;
}
private static DialogResult ShowCore(
IWin32Window? owner,
string? text,
string? caption,
MessageBoxButtons buttons,
MessageBoxIcon icon,
MessageBoxDefaultButton defaultButton,
MessageBoxOptions options,
bool showHelp)
{
if (LocalAppContextSwitches.NoClientNotifications)
{
return DialogResult.None;
}
MESSAGEBOX_STYLE style = GetMessageBoxStyle(owner, buttons, icon, defaultButton, options, showHelp);
HandleRef<HWND> handle = default;
if (showHelp || ((options & (MessageBoxOptions.ServiceNotification | MessageBoxOptions.DefaultDesktopOnly)) == 0))
{
handle = owner is null ? Control.GetHandleRef(PInvoke.GetActiveWindow()) : Control.GetSafeHandle(owner);
}
if (Application.UseVisualStyles)
{
// CLR4.0 or later, shell32.dll needs to be loaded explicitly.
if (PInvoke.GetModuleHandle(Libraries.Shell32) == 0)
{
if (PInvoke.LoadLibraryFromSystemPathIfAvailable(Libraries.Shell32) == HINSTANCE.Null)
{
int lastWin32Error = Marshal.GetLastWin32Error();
throw new Win32Exception(lastWin32Error, string.Format(SR.LoadDLLError, Libraries.Shell32));
}
}
}
// Activate theming scope to get theming for controls at design time and when hosted in browser.
// NOTE: If a theming context is already active, this call is very fast, so shouldn't be a perf issue.
using ThemingScope scope = new(Application.UseVisualStyles);
Application.BeginModalMessageLoop();
try
{
return (DialogResult)PInvoke.MessageBox(handle.Handle, text, caption, style);
}
finally
{
Application.EndModalMessageLoop();
// Right after the dialog box is closed, Windows sends WM_SETFOCUS back to the previously active control
// but since we have disabled this thread main window the message is lost. So we have to send it again after
// we enable the main window.
PInvoke.SendMessage(handle, PInvoke.WM_SETFOCUS);
}
}
}
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