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

namespace screenT
{
 public partial class ScreenForm : Form
 {
 public ScreenForm()
 {
 InitializeComponent();
 }


 private void ScreenCapture()
 {
 DLL.PrScrn();
 }

 protected override void WndProc(ref Message m)
 {
 base.WndProc(ref m);
 Hotkey.ProcessHotKey(m);
 }

 private void button1_Click(object sender, EventArgs e)
 {
 DLL.PrScrn();
 }

 private void Form1_Load(object sender, EventArgs e)
 {
 //注冊熱鍵(窗體句柄,熱鍵ID,輔助鍵,實鍵) 
 try
 {
 Hotkey.Regist(Handle, HotkeyModifiers.MOD_ALT, Keys.F1, ScreenCapture);
 }
 catch (Exception te)
 {
 MessageBox.Show("Alt + A 熱鍵被占用");
 }
 }

 private void Form1_FormClosed(object sender, FormClosedEventArgs e)
 {
 //注消熱鍵(句柄,熱鍵ID) 
 Hotkey.UnRegist(Handle, ScreenCapture);
 }
 }

 public class DLL
 {
 [DllImport("PrScrn.dll", EntryPoint = "PrScrn")]
 public static extern int PrScrn(); //與dll中一致 
 }


 public static class Hotkey
 {
 #region 系統api

 [DllImport("user32.dll")]
 [return: MarshalAs(UnmanagedType.Bool)]
 private static extern bool RegisterHotKey(IntPtr hWnd, int id, HotkeyModifiers fsModifiers, Keys vk);

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

 #endregion

 public delegate void HotKeyCallBackHanlder();

 private const int WM_HOTKEY = 0x312;
 private static int keyid = 10;

 private static readonly Dictionary<int, HotKeyCallBackHanlder> keymap =
 new Dictionary<int, HotKeyCallBackHanlder>();

 /// <summary>
 /// 注冊快捷鍵
 /// </summary>
 /// <param name="hWnd">持有快捷鍵窗口的句柄</param>
 /// <param name="fsModifiers">組合鍵</param>
 /// <param name="vk">快捷鍵的虛擬鍵碼</param>
 /// <param name="callBack">回調函數</param>
 public static void Regist(IntPtr hWnd, HotkeyModifiers fsModifiers, Keys vk, HotKeyCallBackHanlder callBack)
 {
 int id = keyid++;
 if (!RegisterHotKey(hWnd, id, fsModifiers, vk))
 throw new Exception("regist hotkey fail.");
 keymap[id] = callBack;
 }

 /// <summary>
 /// 注銷快捷鍵
 /// </summary>
 /// <param name="hWnd">持有快捷鍵窗口的句柄</param>
 /// <param name="callBack">回調函數</param>
 public static void UnRegist(IntPtr hWnd, HotKeyCallBackHanlder callBack)
 {
 foreach (var var in keymap)
 {
 if (var.Value == callBack)
 UnregisterHotKey(hWnd, var.Key);
 }
 }

 /// <summary>
 /// 快捷鍵消息處理
 /// </summary>
 public static void ProcessHotKey(Message m)
 {
 if (m.Msg == WM_HOTKEY)
 {
 int id = m.WParam.ToInt32();
 HotKeyCallBackHanlder callback;
 if (keymap.TryGetValue(id, out callback))
 {
 callback();
 }
 }
 }
 }

 public enum HotkeyModifiers
 {
 MOD_ALT = 0x1,
 MOD_CONTROL = 0x2,
 MOD_SHIFT = 0x4,
 MOD_WIN = 0x8
 }
}