用 C# 實現截圖功能（三）：熱鍵、系統匣圖示與單一執行個體（完）

取消按鈕事件

private void btnCancel_Click(object sender, EventArgs e)
{
    this.Close();
}

熱鍵設定視窗 Load 事件

private void SetHotKey_Load(object sender, EventArgs e)
{
    comboBox1.Text = Settings.Default.HotKey.ToString();
}

6. 防止程式重複執行

修改 Program.cs，使用 Mutex 或處理序檢查確保單一執行個體：

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

namespace ScreenCutter
{
    static class Program
    {
        [DllImport("User32.dll")]
        private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);
        [DllImport("User32.dll")]
        private static extern bool SetForegroundWindow(IntPtr hWnd);
        private const int WS_SHOWNORMAL = 1;

        [STAThread]
        static void Main()
        {
            Process instance = RunningInstance();
            if (instance == null)
            {
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new MainForm());
            }
            else
            {
                HandleRunningInstance(instance);
            }
        }

        public static Process RunningInstance()
        {
            Process current = Process.GetCurrentProcess();
            Process[] processes = Process.GetProcessesByName(current.ProcessName);
            foreach (Process process in processes)
            {
                if (process.Id != current.Id)
                {
                    if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") == process.MainModule.FileName)
                        return process;
                }
            }
            return null;
        }

        public static void HandleRunningInstance(Process instance)
        {
            ShowWindowAsync(instance.MainWindowHandle, WS_SHOWNORMAL);
            SetForegroundWindow(instance.MainWindowHandle);
        }
    }
}

至此截圖程式基本完成，預設熱鍵 Ctrl+Alt+A。

注意： 程式需用到游標檔 (.cur)、圖示 (.ico) 與圖片，請自行複製至對應目錄或修改程式碼路徑。