我需要关闭Web浏览器控件中的下载弹出窗口(禁止用户下载文件)。
我怎样才能做到这一点?
我找到了这个:
How to block downloads in .NET WebBrowser control?
我用了第二个答案。它正在工作,但是我有问题。似乎调用创建的对象的GetText会阻塞整个线程。我对此没有任何解决方案。
private static void WinEventProc(IntPtr hWinEventHook, uint eventType, IntPtr hwnd, int idObject, int idChild, uint dwEventThread, uint dwmsEventTime)
{
if (idObject == 0 && idChild == 0)
{
if(eventType == EVENT_OBJECT_CREATE)
{
string text = GetText(hwnd);
if (text.Contains("File Download"))
SendMessage(hwnd, 0x0010, IntPtr.Zero, IntPtr.Zero); //close window
}
}
}
public static string GetText(IntPtr hWnd)
{
int length = GetWindowTextLength(hWnd); //my app is freezing here - i think it's because i'm calling it from message loop.
StringBuilder sb = new StringBuilder(length + 1);
GetWindowText(hWnd, sb, sb.Capacity);
return sb.ToString();
}
//编辑
好的,谢谢@sgorozco的建议。现在,我正在使用SetWindowsHookEx和WH_CBT。然后在消息循环中,我捕获了HCBT_CREATEWND事件。但是我从lparm获取CBT_CREATEWND有问题。我收到“托管调试助手'FatalExecutionEngineError'”异常。
这是我当前的代码:
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public struct CREATESTRUCT
{
public IntPtr lpCreateParams;
public IntPtr hInstance;
public IntPtr hMenu;
public IntPtr hwndParent;
public int cy;
public int cx;
public int y;
public int x;
public int style;
public string lpszName;
public string lpszClass;
public int dwExStyle;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public struct CBT_CREATEWND
{
public IntPtr lpcs;
public IntPtr hwndInsertAfter;
}
private static IntPtr MessageLoopFuctnion(int code, IntPtr wParam, IntPtr lParam)
{
if (code < 0)
{
return CallNextHookEx(IntPtr.Zero, code, wParam, lParam);
}
if(code == 3)
{
CBT_CREATEWND info;
info = (CBT_CREATEWND)Marshal.PtrToStructure(lParam, typeof(CBT_CREATEWND));
CREATESTRUCT info1;
info1 = (CREATESTRUCT)Marshal.PtrToStructure(info.lpcs, typeof(CREATESTRUCT)); //here exception is throwing
if (info1.lpszName != null && info1.lpszName.Contains("File Download")))
SendMessage(wParam, 0x0010, IntPtr.Zero, IntPtr.Zero); //close popup
//Marshal.FreeHGlobal(info.lpcs); //error, why?
//Marshal.FreeHGlobal((IntPtr)lParam.ToUInt64());
}
return CallNextHookEx(IntPtr.Zero, code, wParam, lParam);
}
//set hook
IntPtr hWinEventHook = SetWindowsHookEx(5, myCallbackDelegate, user32DLL, 0);
//编辑2
这是我的定义:
private delegate IntPtr HookProc(int code, IntPtr wParam, IntPtr lParam);
private static HookProc myCallbackDelegate = new HookProc(MessageLoopFuctnion);
[DllImport("user32.dll", SetLastError = true)]
static extern IntPtr SetWindowsHookEx(int hookType, HookProc lpfn, IntPtr hMod, uint dwThreadId);
[DllImport("user32.dll")]
static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);
我的myCallbackDelegate是一个静态字段,因此肯定不是GC收集的。
临时,我每500ms枚举所有窗口,然后查找包含文本“文件下载”的对话框。但这是一个丑陋的解决方案。
最佳答案
FatalExecutionEngineError的原因是CREATESTRUCT中的字符串。用IntPtr替换它们,您将不会例外。
[StructLayout(LayoutKind.Sequential)]
public struct CREATESTRUCT {
public IntPtr lpCreateParams;
public IntPtr hInstance;
public IntPtr hMenu;
public IntPtr hwndParent;
public int cy;
public int cx;
public int y;
public int x;
public int style;
public IntPtr lpszName;
public IntPtr lpszClass;
public int dwExStyle;
}
(也许您可以改用GetClassName和GetWindowText作为替代方法。未经测试)
关于c# - 消息循环正在阻止应用程序,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/21392465/