您好我得到了'不一致的可访问性：参数类型'clsWebCamArgs'比委托'ctrlCamera.WebCamEventHandler'更难访问。任何人都可以提供任何有关下面的代码错误的见解。
using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;
namespace PayrollSystem
{
[ToolboxBitmap(typeof(ctrlCamera), "Camera.ico")] // toolbox bitmap
[Designer("Sytem.Windows.Forms.Design.ParentControlDesigner,System.Design", typeof(IDesigner))] // make composite
public partial class ctrlCamera : UserControl
{
public ctrlCamera(){InitializeComponent();}
// property variables
private int m_TimeToCapture_milliseconds = 100;
private int m_Width = 320;
private int m_Height = 240;
private int mCapHwnd;
private ulong m_FrameNumber = 0;
// global variables to make the video capture go faster
private PayrollSystem.clsWebCamArgs x = new PayrollSystem.clsWebCamArgs();
private IDataObject tempObj;
private Image tempImg;
private bool bStopped = true;
// event delegate
public delegate void WebCamEventHandler(object source, PayrollSystem.clsWebCamArgs e);
// fired when a new image is captured
public event WebCamEventHandler ImageCaptured;
#region API Declarations
[DllImport("user32", EntryPoint = "SendMessage")]
public static extern int SendMessage(int hWnd, uint Msg, int wParam, int lParam);
[DllImport("avicap32.dll", EntryPoint = "capCreateCaptureWindowA")]
public static extern int capCreateCaptureWindowA(string lpszWindowName, int dwStyle, int X, int Y, int nWidth, int nHeight, int hwndParent, int nID);
[DllImport("user32", EntryPoint = "OpenClipboard")]
public static extern int OpenClipboard(int hWnd);
[DllImport("user32", EntryPoint = "EmptyClipboard")]
public static extern int EmptyClipboard();
[DllImport("user32", EntryPoint = "CloseClipboard")]
public static extern int CloseClipboard();
#endregion
#region API Constants
public const int WM_USER = 1024;
public const int WM_CAP_CONNECT = 1034;
public const int WM_CAP_DISCONNECT = 1035;
public const int WM_CAP_GET_FRAME = 1084;
public const int WM_CAP_COPY = 1054;
public const int WM_CAP_START = WM_USER;
public const int WM_CAP_DLG_VIDEOFORMAT = WM_CAP_START + 41;
public const int WM_CAP_DLG_VIDEOSOURCE = WM_CAP_START + 42;
public const int WM_CAP_DLG_VIDEODISPLAY = WM_CAP_START + 43;
public const int WM_CAP_GET_VIDEOFORMAT = WM_CAP_START + 44;
public const int WM_CAP_SET_VIDEOFORMAT = WM_CAP_START + 45;
public const int WM_CAP_DLG_VIDEOCOMPRESSION = WM_CAP_START + 46;
public const int WM_CAP_SET_PREVIEW = WM_CAP_START + 50;
#endregion
#region Control Properties
public int TimeToCapture_milliseconds
{
get { return m_TimeToCapture_milliseconds; }
set { m_TimeToCapture_milliseconds = value; }
}
public int CaptureHeight
{
get { return m_Height; }
set { m_Height = value; }
}
public int CaptureWidth
{
get { return m_Width; }
set { m_Width = value; }
}
public ulong FrameNumber
{
get { return m_FrameNumber; }
set { m_FrameNumber = value; }
}
#endregion
#region Start and Stop Capture Functions
public void Start(ulong FrameNum)
{
try
{
// for safety, call stop, just in case we are already running
this.Stop();
// setup a capture window
mCapHwnd = capCreateCaptureWindowA("WebCap", 0, 0, 0, m_Width, m_Height, this.Handle.ToInt32(), 0);
// connect to the capture device
Application.DoEvents();
SendMessage(mCapHwnd, WM_CAP_CONNECT, 0, 0);
SendMessage(mCapHwnd, WM_CAP_SET_PREVIEW, 0, 0);
// set the frame number
m_FrameNumber = FrameNum;
// set the timer information
this.timer1.Interval = m_TimeToCapture_milliseconds;
bStopped = false;
this.timer1.Start();
}
catch (Exception excep)
{
MessageBox.Show("An error ocurred while starting the video capture. Check that your webcamera is connected properly and turned on.\r\n\n" + excep.Message);
this.Stop();
}
}
public void Stop()
{
try
{
// stop the timer
bStopped = true;
this.timer1.Stop();
// disconnect from the video source
Application.DoEvents();
SendMessage(mCapHwnd, WM_CAP_DISCONNECT, 0, 0);
}
catch (Exception excep)
{ // don't raise an error here.
}
}
#endregion
#region Video Capture Code
private void timer1_Tick(object sender, EventArgs e)
{
try
{
// pause the timer
this.timer1.Stop();
// get the next frame;
SendMessage(mCapHwnd, WM_CAP_GET_FRAME, 0, 0);
// copy the frame to the clipboard
SendMessage(mCapHwnd, WM_CAP_COPY, 0, 0);
// paste the frame into the event args image
if (ImageCaptured != null)
{
// get from the clipboard
tempObj = Clipboard.GetDataObject();
tempImg = (Bitmap)tempObj.GetData(DataFormats.Bitmap);
x.WebCamImage = tempImg.GetThumbnailImage(m_Width, m_Height, null, IntPtr.Zero);
// raise the event
this.ImageCaptured(this, x);
}
// restart the timer
Application.DoEvents();
if (!bStopped)
this.timer1.Start();
}
catch (Exception excep)
{
MessageBox.Show("An error ocurred while capturing the video image. The video capture will now be terminated.\r\n\n" + excep.Message);
this.Stop(); // stop the process
}
}
#endregion
}
}
答案 0 :(得分：2)
你宣布
public delegate void WebCamEventHandler(object source, PayrollSystem.clsWebCamArgs e);
为public，意味着它应该可以从到处访问（甚至可以从其他程序集中访问）。
但似乎（虽然我找不到你展示的代码）PayrollSystem.clsWebCamArgs 不声明public，所以不是像代表一样可以访问。
因此编译器会给你一个错误，因为如果无法访问其中一个参数的类型，就无法从其他程序集中访问WebCamEventHandler。
要解决此问题，您可以将WebCamEventHandler的声明更改为internal，也可以将clsWebCamArgs的声明更改为public。