How would I implement the IDispatch interface to handle the following in
VB.Net
<BEGIN>
Controlling Download and Execution
The WebBrowser Control gives you control over what it downloads, displays,
and executes. To gain this control, you need to implement your host's
IDispatch so it handles DISPID_AMBIENT_DLCONTROL. When the WebBrowser
Control is instantiated, it will call your IDispatch::Invoke with this ID.
Set pvarResult to a combination of following flags, using the bitwise OR
operator, to indicate your preferences.
a.. DLCTL_DLIMAGES, DLCTL_VIDEOS, and DLCTL_BGSOUNDS: Images, videos, and
background sounds will be downloaded from the server and displayed or played
if these flags are set. They will not be downloaded and displayed if the
flags are not set.
b.. DLCTL_NO_SCRIPTS and DLCTL_NO_JAVA: Scripts and Java applets will not
be executed.
c.. DLCTL_NO_DLACTIVEXCTLS and DLCTL_NO_RUNACTIVEXCTLS : ActiveX controls
will not be downloaded or will not be executed.
d.. DLCTL_DOWNLOADONLY: The page will only be downloaded, not displayed.
e.. DLCTL_NO_FRAMEDOWNLOAD: The WebBrowser Control will download and parse
a frameSet, but not the individual frame objects within the frameSet.
f.. DLCTL_RESYNCHRONIZE and DLCTL_PRAGMA_NO_CACHE: These flags cause cache
refreshes. With DLCTL_RESYNCHRONIZE, the server will be asked for update
status. Cached files will be used if the server indicates that the cached
information is up-to-date. With DLCTL_PRAGMA_NO_CACHE, files will be
re-downloaded from the server regardless of the update status of the files.
g.. DLCTL_NO_BEHAVIORS: Behaviors are not downloaded and are disabled in
the document.
h.. DLCTL_NO_METACHARSET_HTML: Character sets specified in meta elements
are suppressed.
i.. DLCTL_URL_ENCODING_DISABLE_UTF8 and DLCTL_URL_ENCODING_ENABLE_UTF8:
These flags function similarly to the
DOCHOSTUIFLAG_URL_ENCODING_DISABLE_UTF8 and
DOCHOSTUIFLAG_URL_ENCODING_ENABLE_UTF8 flags used with
IDocHostUIHandler::GetHostInfo. The difference is that the DOCHOSTUIFLAG
flags are checked only when the WebBrowser Control is first instantiated.
The download flags here for the ambient property change are checked whenever
the WebBrowser Control needs to perform a download.
j.. DLCTL_NO_CLIENTPULL: No client pull operations will be performed.
k.. DLCTL_SILENT: No user interface will be displayed during downloads.
l.. DLCTL_FORCEOFFLINE: The WebBrowser Control always operates in offline
mode.
m.. DLCTL_OFFLINEIFNOTCONNECTED and DLCTL_OFFLINE: These flags are the
same. The WebBrowser Control will operate in offline mode if not connected
to the Internet.
DISPID_AMBIENT_DLCONTROL and the flag values are defined in mshtmdid.h.
Initially, when the function call to IDispatch::Invoke starts, the VARIANT
to which the parameter pvarResult points is of type VT_EMPTY. You must
switch the type to VT_I4 for any settings to have an effect. You can place
your flag values in the lVal member of the VARIANT.
Most of the flag values have negative effects, that is, they prevent
behavior that normally happens. For instance, scripts are normally executed
by the WebBrowser Control if you don't customize its behavior. But if you
set the DLCTL_NOSCRIPTS flag, no scripts will execute in that instance of
the control. However, three flags-DLCTL_DLIMAGES, DLCTL_VIDEOS, and
DLCTL_BGSOUNDS-work exactly opposite. If you set flags at all, you must set
these three for the WebBrowser Control to behave in its default manner
vis-a-vis images, videos and sounds.
The following code sample causes a WebBrowser Control instance to download
and display images and videos, but not background sounds, since the
DLCTL_BGSOUNDS is not explicitly set. Also, script execution on pages
displayed by the WebBrowser Control is disabled.
STDMETHODIMP CAtlBrCon::Invoke(DISPID dispidMember, REFIID riid,
LCID lcid, WORD wFlags,
DISPPARAMS* pDispParams,
VARIANT* pvarResult,
EXCEPINFO* pExcepInfo,
UINT* puArgErr)
{
switch (dispidMember)
{
case DISPID_AMBIENT_DLCONTROL:
pvarResult->vt = VT_I4;
pvarResult->lVal = DLCTL_DLIMAGES | DLCTL_VIDEOS | DLCTL_NO_SCRIPTS;
break;
default:
return DISP_E_MEMBERNOTFOUND;
}
return S_OK;
}
<END>Thanks so much for your help. Contributors will be listed in the
freeware browser being developed.
