I am loading an local disk drive _test.htm file through IPersistMoniker Load method. From what I believe, it is supposed to add the path to the relative URLs as base path. Problem is - it does not do so. Instead, it takes a very long time trying to resolve the path from Internet until it gives up (about 20-30 seconds). What I want is to give up instantly, as soon as the unsolvable path is detected (since it is a local disk file anyway).
This is an example HTML I am loading:
<html>
<head>
<script src="//test/test.js"></script>
<head>
<body>
<img src="image.jpg">
<img src="/image.jpg">
<img src="//image.jpg">
</body>
</html>
Simplified code (C++ Builder) with no error checking:
WideString URL = "file:///" + StringReplace(ExtractFilePath(Application->ExeName), "\\", "/", TReplaceFlags() << rfReplaceAll) + "_test.htm";
TCppWebBrowser* WB = CppWebBrowser1;
DelphiInterface<IMoniker> pMoniker;
OleCheck(CreateURLMonikerEx(NULL, URL.c_bstr(), &pMoniker, URL_MK_UNIFORM));
DelphiInterface<IHTMLDocument2> diDoc2 = WB->Document;
DelphiInterface<IPersistMoniker> pPrstMnkr;
OleCheck(diDoc2->QueryInterface(IID_IPersistMoniker, (LPVOID*)&pPrstMnkr));
DelphiInterface<IBindCtx> pBCtx;
OleCheck(CreateBindCtx(0, &pBCtx));
pPrstMnkr->Load(0, pMoniker, pBCtx, STGM_READWRITE);
Problem - image.jpg loads fine, but the paths //test/test.js and /image.jpg and //image.jpg take a very long time to resolve/load. From what I understand CreateURLMonikerEx is supposed to use file:///path/to/executable/ and prepend that automatically to these paths in which case they would fail instantly - file:///path/to/executable//test/test.js for example. That does not happen.
I additionally tried to move image.jpg to a subfolder and then create custom IMoniker interface with the GetDisplayName and BindToStorage implementation which loaded the image from a custom path. However it doesn't do the same for paths which start with // or /. Even though I output file:///path/to/executable/ in the GetDisplayName through the *ppszDisplayName parameter.
How can I avoid extended time loading such unusable links (discard them), or redirect them to local path as above?
I found a partial solution to use about:blank in the *ppszDisplayName but then it doesn't load images with the valid path image.jpg as then it loads them as about:image.jpg which again is invalid path.
Additionally - I've tried adding IDocHostUIHandler interface with the implementation of Invoke method (DISPID_AMBIENT_DLCONTROL) with the pVarResult->lVal = DLCTL_NO_SCRIPTS | DLCTL_NO_JAVA | DLCTL_NO_RUNACTIVEXCTLS | DLCTL_NO_DLACTIVEXCTLS | DLCTL_NO_FRAMEDOWNLOAD | DLCTL_FORCEOFFLINE; - it it blocks the download of images entirely, but still does check 20-30 seconds for the links starting with // or /.
Update - this doesn't work well!
The code below doesn't work well! The problem is - it loses
<BODY>tag attributes. BODY tag turns out entirely empty after loading. I ended up loading the message usingIHTMLDocument2.writemethod.See: Assigning IHTMLDocument2 instance to a TWebBrowser instance
After spending lots of time and no guidance of any kind here, I believe that it is not possible to avoid this wait 20-30 sec when the links are invalid. I found another solution and if someone wants to supplement this solution, feel free to do so.
Instead what I had to do is to create an instance of CLSID_HTMLDocument (IHTMLDocument3 or IHTMLDocument2 interface) and then load the document into that container and parse the links prior to doing anything with them. This is described on:
https://learn.microsoft.com/en-us/previous-versions/aa703592(v=vs.85)
This also helped:
After parsing the document URLs and fixing the invalid ones, it can be saved/displayed in the actual TWebBrowser.
Rough solution (C++ Builder):
try
{
DelphiInterface<IHTMLDocument2> diDoc2;
OleCheck(CoCreateInstance(CLSID_HTMLDocument, NULL, CLSCTX_INPROC_SERVER, IID_IHTMLDocument2, (void**)&diDoc2));
DelphiInterface<IPersistStreamInit> diPersist;
OleCheck(diDoc2->QueryInterface(IID_IPersistStreamInit, (void**)&diPersist));
OleCheck(diPersist->InitNew());
DelphiInterface<IMarkupServices> diMS;
OleCheck(diDoc2->QueryInterface(IID_IMarkupServices, (void**)&diMS));
DelphiInterface<IMarkupPointer> diMkStart;
DelphiInterface<IMarkupPointer> diMkFinish;
OleCheck(diMS->CreateMarkupPointer(&diMkStart));
OleCheck(diMS->CreateMarkupPointer(&diMkFinish));
// ...Load from file or memory stream into your WideString here...
DelphiInterface<IMarkupContainer> diMC;
OleCheck(diMS->ParseString(WideString(MsgHTMLSrc).c_bstr(), 0, &diMC, diMkStart, diMkFinish));
DelphiInterface<IHTMLDocument2> diDoc;
OleCheck(diMC->QueryInterface(IID_PPV_ARGS(&diDoc)));
DelphiInterface<IHTMLElementCollection> diCol;
OleCheck(diDoc->get_all(&diCol));
long ColLen = 0;
OleCheck(diCol->get_length(&ColLen));
for (int i = 0; i < ColLen; ++i)
{
DelphiInterface<IDispatch> diItem;
diCol->item(OleVariant(i), OleVariant(i), &diItem);
DelphiInterface<IHTMLElement> diElem;
OleCheck(diItem->QueryInterface(IID_IHTMLElement, (void**)&diElem));
WideString wTagName;
OleCheck(diElem->get_tagName(&wTagName));
if (StartsText("img", wTagName))
{
OleVariant vSrc;
OleCheck(diElem->getAttribute(OleVariant("src"), 4, vSrc));
// Make changes to vSrc here....
// And save it back to src
OleCheck(diElem->setAttribute(OleVariant("src"), vSrc, 0));
}
else if (StartsText("script", wTagName))
{
// More parsing here...
}
}
}
catch (EOleSysError& e)
{
// Process exception as needed
}
catch (Exception& e)
{
// Process exception as needed
}
After full parsing of all required elements (img/src, script/src, base/href etc.) save and load into TWebBrowser.
I only now have to see if the parsed HTML IHTMLDocument2 can be directly assigned to TWebBrowser without loading it again, but that is another question (See - Assigning IHTMLDocument2 instance to a TWebBrowser instance)