First let me explain why I called the article "3rd Way". I've already seen
such articles on CodeGuru, explaining how to load and parse HTML file from
memory. You may ask, so why I'm writing another guide? Well, below I'll show
advantages and disadvantages that I found in those ways.
First one, which is also shown in MSDN , is to load HTML code using
IStream interface. You can
read the article about it here. If all you want is to put a new code into your document,
you should definately use this one. But if you'll try to get tags from your
document after you load HTML, you will get nothing. Just because they are still
in parsing and you have to create an
OnDocumentComplete handler and only than
start to look inside your document.
When I realized this I went to look for another way that will give me
document immediately after submitting a code. And yes, I found it! You can look
at the great article by Asher
Kobin at CodeGuru. It uses a new interface called
IMarkupServices, introduced with MS Internet
Explorer 5.0. I picked this code and made my own from it and started using
it.... but suddenly I saw that when I'm saving my document to disk, the BODY tag
has no attributes! I worked on this problem a whole day, trying to get it
working, but... nothing. When you load your HTML code from memory into document,
all attributes of BODY tag are gone. Still have no idea why it is happening and
glad if someone will tell me.
Thus I came to MSDN again and found another, third way to load and parse
HTML. I was so happy, so I decided to write my first article to CodeProject
about it, which you are reading now :)
For those, advanced programmers, that don't want to read a whole article, I
will give a hint: loading HTML code is made by
write() method of
Now I'll explain how to do this from beginning.
Headers and imports
I'll assume here, that you have a standard MFC application (such as Dialog ,
SDI or MDI applications). First of all you have to initialize COM, since we
gonna use MSHTML COM interfaces. This can be done in
InitInstance() function of
your application. Remember also to uninitialize COM in your
Now in the file you are going to use MSHTML interfaces,
comdef.h (for smart pointers) and import
#pragma warning(disable : 4146) //see Q231931 for explaintation
#import <mshtml.tlb> no_auto_exclude
Where do I get a document?
Now let's get a pointer to
IHTMLDocument interface. How you will get it?
Depends on what you already have :) If you are hosting a
WebBrowser control or
CHtmlView in your application, u can call
GetDocument() function in store
the return value in your pointer, but I will explain how to get a 'free'
document, which is not attached to any control or view. This can be done by
simple call to
HRESULT hr = CoCreateInstance(CLSID_HTMLDocument, NULL, CLSCTX_INPROC_SERVER,
Validate that you have a valid pointer (not
NULL) and move on.
Converting your HTML code
I'll assume that you have all HTML code you want to load
in some variable called
lpszHTMLCode. This can be
CString or any other buffer,
loaded for example from file on disk. We need to prepare it before passing to
MSHTML. The problem is that MSHTML function we are going to use takes only
SAFEARRAY as parameter. So let's convert our string to
SAFEARRAY* psa = SafeArrayCreateVector(VT_VARIANT, 0, 1);
bstr_t bsData = (LPCTSTR)lpszHTMLCode;
hr = SafeArrayAccessData(psa, (LPVOID*)¶m);
param->vt = VT_BSTR;
param->bstrVal = (BSTR)bsData;
Now we are ready to pass our
function. These 2 lines of code will do all dirty parsing work for you
hr = pDoc->write(psa); //write your buffer
hr = pDoc->close(); //and closes the document, "applying" your code
//Don't forget to free the SAFEARRAY!
Of course, remember to check every your step, so your
program never crush, I skipped it to keep the code simple.
Now, after all this work you have a pointer to IHTMLDocument2
interface, which gives you a lot of features, like getting particular tag,
searching, inserting, replacing, deleting tag, just like you do it in
And remember, if you are using smart pointers (like I do
here) you don't need to call Release() function, the object will be freed
"about:blank" bug workaround
Well, since we have no site "attached" to our document interface, all links (href, src) that are relative to document, will start with "about:blank" if you'll try to use
IHTMLAnchorElement::href property. The way to get the exact link, as it is in HTML source, is to use
IHTMLElement interface with nice function called
getAttribute. Just remember that the second parameter of this function should be 2, it will tell to parser to return you text as is.
Of course same way you should work with IMG, LINK and other tags. The example project updated with this fix also. You can download it and see how I did it.
Ahser Kobin's article about parsing with IMarkupServices
Load HTML from Stream (MSDN)
MSHTML Reference (MSDN)
IHTMLDocument2 Reference (MSDN)