ScreenCaptureApp/MainForm.cs

using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace ScreenCaptureApp
{
    public partial class MainForm : Form
    {
        [DllImport("user32.dll")]
        private static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, int vk);

        [DllImport("user32.dll")]
        private static extern bool UnregisterHotKey(IntPtr hWnd, int id);

        private const int WM_HOTKEY = 0x0312;
        private const int PRINT_SCREEN_ID = 1;
        private bool captureOnKeyPress = true;

        public MainForm()
        {
            InitializeComponent();
            if (!RegisterHotKey(this.Handle, PRINT_SCREEN_ID, 0x0, 0x2C))
            {
                notifyIcon1.ShowBalloonTip(1000, "Error", "Failed to register Print Screen hotkey", ToolTipIcon.Error);
            }
            this.WindowState = FormWindowState.Minimized;
        }

        protected override void WndProc(ref Message m)
        {
            if (m.Msg == WM_HOTKEY && captureOnKeyPress)
            {
                if (m.WParam.ToInt32() == PRINT_SCREEN_ID)
                {
                    CaptureScreen();
                }
            }
            base.WndProc(ref m);
        }

        private void CaptureScreen()
        {
            using (ScreenCaptureForm captureForm = new ScreenCaptureForm())
            {
                captureForm.Focus();
                if (captureForm.ShowDialog() == DialogResult.OK)
                {
                    using (captureForm.CapturedImage)
                    {
                        using (ResultForm resultForm = new ResultForm(captureForm.CapturedImage))
                        {
                            if (resultForm.ShowDialog() == DialogResult.OK)
                            {
                                using (SaveFileDialog sfd = new SaveFileDialog())
                                {
                                    sfd.Title = "Save screenshot";
                                    sfd.Filter = "PNG Image|*.png|JPEG Image|*.jpg|Bitmap Image|*.bmp";
                                    sfd.FileName = $"screenshot_{DateTime.Now:dd-MM-yyyy_HH.mm.ss}";

                                    if (sfd.ShowDialog() == DialogResult.OK)
                                    {
                                        captureForm.CapturedImage.Save(sfd.FileName, GetImageFormat(sfd.FileName));
                                        notifyIcon1.ShowBalloonTip(1000, "Success", "Screenshot saved!", ToolTipIcon.Info);
                                    }
                                }
                            }
                            else if (resultForm.DialogResult == DialogResult.Yes)
                            {
                                try
                                {
                                    Clipboard.SetImage(captureForm.CapturedImage);
                                    notifyIcon1.ShowBalloonTip(1000, "Success", "Copied to clipboard!", ToolTipIcon.Info);
                                }
                                catch (Exception ex)
                                {
                                    notifyIcon1.ShowBalloonTip(1000, "Error", $"Copy failed: {ex.Message}", ToolTipIcon.Error);
                                }
                            }
                        }
                    }
                }
            }
        }

        private System.Drawing.Imaging.ImageFormat GetImageFormat(string fileName)
        {
            string ext = System.IO.Path.GetExtension(fileName).ToLower();
            switch (ext)
            {
                case ".jpg": return System.Drawing.Imaging.ImageFormat.Jpeg;
                case ".jpeg": return System.Drawing.Imaging.ImageFormat.Jpeg;
                case ".bmp": return System.Drawing.Imaging.ImageFormat.Bmp;
                default: return System.Drawing.Imaging.ImageFormat.Png;
            }
        }

        private void MainForm_Load(object sender, EventArgs e)
        {
            disablePrintScreenCaptureToolStripMenuItem.Text = $"Print Screen Capture: {(captureOnKeyPress ? "ON" : "OFF")}";
            this.Hide();
        }

        private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
        {
            UnregisterHotKey(this.Handle, PRINT_SCREEN_ID);
            notifyIcon1.Visible = false;
            this.Dispose(true);
        }

        private void notifyIcon1_MouseClick(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Right)
            {
                MethodInvoker mi = new MethodInvoker(() => {
                    notifyIcon1.ContextMenuStrip.Show(Cursor.Position);
                });
                this.BeginInvoke(mi);
            }
            else if (e.Button == MouseButtons.Left)
            {
                CaptureScreen();
            }
        }

        private void toggleHotkeyToolStripMenuItem_Click(object sender, EventArgs e)
        {
            captureOnKeyPress = !captureOnKeyPress;
            disablePrintScreenCaptureToolStripMenuItem.Text = $"Print Screen Capture: {(captureOnKeyPress ? "ON" : "OFF")}";
            notifyIcon1.ShowBalloonTip(250, "Screen Capture",
                captureOnKeyPress ? "Print Screen capture enabled" : "Print Screen capture disabled",
                ToolTipIcon.Info);
        }

        private void exitToolStripMenuItem_Click(object sender, EventArgs e)
        {
            base.OnFormClosing(e as FormClosingEventArgs);
            Application.Exit();
        }

        private void bigButton_Click(object sender, EventArgs e)
        {
            CaptureScreen();
        }
    }
}