Question

How to determine if a window is visible or not in C#

Answer 1

using System.Runtime.InteropServices;

namespace WinFormsApp1
{
    public partial class Form1 : Form
    {
        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        static extern bool IsWindowVisible(IntPtr hWnd);

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (IsWindowVisible(this.Handle))
            {
                MessageBox.Show("yes");
            } 
            else
            {
                MessageBox.Show("no");
            }
        }
    }
}



/*
run:

yes

*/

 

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Answer 2

using System.Runtime.InteropServices;

namespace WinFormsApp1
{
    public partial class Form1 : Form
    {
        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        static extern bool IsWindowVisible(IntPtr hWnd);

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            this.Hide();
            if (IsWindowVisible(this.Handle))
            {
                MessageBox.Show("yes");
            } 
            else
            {
                MessageBox.Show("no");
            }
        }
        private void Form1_KeyDown(object sender, KeyEventArgs e)
        {
        }
    }
}



/*
run:

no

*/

 

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