我有下面的代碼到窗體:一個字段初始不能引用非靜態字段,方法或屬性
using System;
using System.Diagnostics;
using System.Drawing;
using System.IO;
using System.Media;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Windows.Forms;
namespace ScreenShots
{
public partial class ScreenShotConfigurationForm : Form
{
// ----- some other stuff (code, methods, etc...) is placed in here -----
private const int WH_KEYBOARD_LL = 13;
private const int WM_KEYDOWN = 0x0100;
private LowLevelKeyboardProc _proc = HookCallback; // <<<< This is the row that is causing the error
private IntPtr _hookID = IntPtr.Zero;
private IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
{
if (nCode >= 0 && wParam == (IntPtr)WM_KEYDOWN)
{
int vkCode = Marshal.ReadInt32(lParam);
if (vkCode == 44) // 44 is the key code of PrintScreen button
{
MakeScreenShot();
}
}
return CallNextHookEx(_hookID, nCode, wParam, lParam);
}
private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);
private IntPtr SetHook(LowLevelKeyboardProc proc)
{
using (Process curProcess = Process.GetCurrentProcess())
using (ProcessModule curModule = curProcess.MainModule)
{
return SetWindowsHookEx(WH_KEYBOARD_LL, proc, GetModuleHandle(curModule.ModuleName), 0);
}
}
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private extern IntPtr SetWindowsHookEx(int idHook, LowLevelKeyboardProc lpfn, IntPtr hMod, uint dwThreadId);
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
private extern bool UnhookWindowsHookEx(IntPtr hhk);
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private extern IntPtr CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);
[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private extern IntPtr GetModuleHandle(string lpModuleName);
}
}
這是給我在微軟C#2008以下錯誤:
甲字段初始不能引用非靜態字段,方法或屬性 'ScreenShots.ScreenShotConfigurationForm.HookCallback(INT,System.IntPtr,System.IntPtr)'
- 是什麼意思?
- 我該如何解決呢?
如果該方法需要現有的形式來開展工作,那麼*它不應該是靜態的*。如果方法的*行爲*是*假設*做它的工作在一個新的形式,而不是一些現有的形式,然後創建一個新的形式是(根據定義)是正確的。 – Servy
如果該方法不需要一個實例來完成它的工作,將其設置爲靜態(和/或將其移出該類)。 – Blorgbeard
*這意味着我必須在每次調用該方法時實例化一個窗體或圖標的新實例* - 不需要 'var myForm = new MyForm1();' 如果您有上述代碼,則您可以使用變量'myForm'調用任何非靜態方法 – Subbu