Search
Module:
Directory

   Desktop Functions:

   Smart Device Functions:


Show Recent Changes
Subscribe (RSS)
Misc. Pages
Comments
FAQ
Helpful Tools
Playground
Suggested Reading
Website TODO List
Download Visual Studio Add-In

IsIconic (user32)
 
.
Summary

C# Signature:

[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool IsIconic(IntPtr hWnd);

VB Signature:

  Private Declare Auto Function IsIconic Lib "user32.dll" (ByVal hwnd As IntPtr) As Boolean

User-Defined Types:

None.

Notes:

The hWnd parameter can be obtained by the Handle property of a Form, or by MainWindowHandle on a Process.

The corresponding unmanaged return type is a 4-byte Win32 'BOOL', so mark the method with the MarshalAsAttribute(UnmanagedType.Bool).

Tips & Tricks:

Please add some!

Sample Code - C# - sivakumar.keerthi

using System;

using System.Drawing;

using System.Collections;

using System.ComponentModel;

using System.Windows.Forms;

using System.Data;

using System.Runtime.InteropServices;

using System.Diagnostics;

namespace WindowsApplication1

{

    /// <summary>
    /// Summary description for Form1.
    /// </summary>
    public class Form1 : System.Windows.Forms.Form
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        [DllImport("user32.dll")]
        public static extern IntPtr FindWindow( string sClsName , string sWndName );
        [DllImport("user32.dll")]
        public static extern int SetForegroundWindow( IntPtr Hwnd );
        [DllImport("user32.dll")]
        public static extern int ShowWindow( IntPtr Hwnd , int iCmdShow );
        [DllImport("user32.dll")]
        public static extern bool IsIconic( IntPtr Hwnd );    

        private const int iRestore = 9;
        private const int iShow = 5;

        private System.ComponentModel.Container components = null;

        public Form1()
        {
            //
            // Required for Windows Form Designer support
            //
            InitializeComponent();
            //
            // TODO: Add any constructor code after InitializeComponent call
            //
        }

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        protected override void Dispose( bool disposing )
        {
            if( disposing )
            {
                if (components != null)
                {
                    components.Dispose();
                }
            }
            base.Dispose( disposing );
        }

        #region Windows Form Designer generated code
        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            //
            // Form1
            //
            this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
            this.ClientSize = new System.Drawing.Size(528, 266);
            this.Name = "Form1";
            this.Text = "Form1";
            this.ResumeLayout(false);

        }
        #endregion

        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Process[] p = Process.GetProcessesByName( Process.GetCurrentProcess().ProcessName , Environment.MachineName );
            if ( p.Length > 1 )
            {
                MessageBox.Show( "Already one instance is running......." );
                Form1 Frm = new Form1();
                Frm.ShowForm();
                return;
            }
            else
                Application.Run(new Form1());
        }

        private void ShowForm()
        {
            IntPtr Hwnd = FindWindow( null , "Form1" );
            if ( Hwnd.ToInt32() > 0 )
            {
                SetForegroundWindow( Hwnd );
                if ( IsIconic( Hwnd ) )
                    ShowWindow( Hwnd , iRestore );
                else
                    ShowWindow( Hwnd , iShow );
            }
        }
    }

}

Sample Code:

      // Want only one instance of an application?

      [DllImport("User32.Dll")]
      private static extern bool SetForegroundWindow(IntPtr hWnd);
      [DllImport("User32.Dll")]
      private static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);
      [DllImport("User32.Dll")]
      private static extern bool IsIconic(IntPtr hWnd);


      private const int SW_RESTORE = 9;

      /// <summary>
      /// Main entry point for the application.
      /// </summary>
      [STAThread]
      static int
      Main
    (
      string[] arguments
    )
    {
      // Check for running instance

      Process thisProcess = Process.GetCurrentProcess();
      Process[] processes = Process.GetProcessesByName(thisProcess.ProcessName);

      if (processes.Length > 1)
        {
          // One is us (which will end); the other we activate

          int index = 0;
          if (processes[index].Id == thisProcess.Id)
        index = 1;

          IntPtr hWnd = processes[index].MainWindowHandle;

          if (IsIconic(hWnd))
        ShowWindowAsync(hWnd, SW_RESTORE);

          SetForegroundWindow(hWnd);

          // Exit
          return 0;
        }


       // Normal startup code continues here...

     }

Alternative Managed API:

Do you know one? Please contribute it!

Documentation
IsIconic on MSDN

Please edit this page!

Do you have...

  • helpful tips or sample code to share for using this API in managed code?
  • corrections to the existing content?
  • variations of the signature you want to share?
  • additional languages you want to include?

Select "Edit This Page" on the right hand toolbar and edit it! Or add new pages containing supporting types needed for this API (structures, delegates, and more).

 
Access PInvoke.net directly from VS:
Terms of Use
Edit This Page
Find References
Show Printable Version
Revisions