URLDownloadToCacheFile
A version of this page is also available for
4/8/2010
This function downloads data into the Internet cache and returns the file name of the cache location for retrieving the bits.
Syntax
HRESULT URLDownloadToCacheFile(
LPUNKNOWN lpUnkcaller,
LPCSTR szURL,
LPTSTR szFileName,
DWORD dwBufLength,
DWORD dwReserved,
IBindStatusCallback* pBSC
);
Parameters
- lpUnkcaller
Address of the controlling IUnknown interface of the calling Microsoft ActiveX component, if the caller is an ActiveX component. If the caller is not an ActiveX component, this value can be set to NULL. Otherwise, the caller is a Component Object Model (COM) object that is contained in another component, such as an ActiveX control within the context of an HTML page. This parameter represents the outermost IUnknown of the calling component. The function attempts the download within the context of the ActiveX client framework and allows the caller's container to receive callbacks on the progress of the download.
- szURL
Address of a string value that contains the URL to be downloaded. This cannot be set to NULL.
- szFileName
Address of a string value that contains the name of the downloaded file. This cannot be set to NULL.
- dwBufLength
Unsigned long integer value that contains the size of the szFileName buffer in bytes.
- dwReserved
Reserved. Must be set to zero.
- pBSC
Address of the caller's IBindStatusCallback interface. URLDownloadToCacheFile calls this interface's IBindStatusCallback::OnProgress method on a connection activity, including the arrival of data. IBindStatusCallback::OnDataAvailable is never called. Implementing IBindStatusCallback::OnProgress allows a caller to implement a user interface or other progress monitoring functionality. It also allows the download operation to be canceled by returning E_ABORT from the IBindStatusCallback::OnProgress call. This can be set to NULL.
Return Value
This function returns one of the values shown in the following table.
| Value | Description |
|---|---|
E_FAIL |
The operation failed. |
E_OUTOFMEMORY |
The buffer length is invalid or there was insufficient memory to complete the operation. |
S_OK |
The operation succeeded. |
Remarks
The client can choose to be notified of progress through a notification callback.
This function always returns a file name if the download operation succeeds. If the given URL is a file: URL, URLDownloadToCacheFile directly returns the file name for the file: URL rather than making a copy to the cache. If the given URL is an Internet URL (http:, ftp:), URLDownloadToCacheFile downloads this file and returns the local file name of the cached copy. Using this function ensures that a file name is returned without unnecessary copying of data.
For Windows Mobile when Internet Explorer Mobile starts to run it will assume that the cache folder is a system folder and make it hidden.
Requirements
| Header | urlmon.h, urlmon.idl |
| Library | urlmon.lib |
| Windows Embedded CE | Windows CE .NET 4.0 and later |
| Windows Mobile | Windows Mobile Version 5.0 and later |