Detailed Description

HTML control (MC_WC_HTML).

As the control name suggests, the control is intended to display HTML documents. Actually the control is thin wrapper of Internet Explorer COM object, so it can do much more: display a plethora of multimedia files, take use of javascript etc.

The easiest way how to show some document is to specify URL of target document as control's window name. For example when created with CreateWindow(), use the 2nd argument as the URL. This allows easy use of the control in dialog templates.

URL can also be set anytime later with message MC_HM_GOTOURL.

The control accepts any protocol understood by the Internet Explorer, for example:

http://www.example.org
file://C:/page.html
res://some_dll/id_of_resource
its:helpFile.chm::page.htm

Resource Protocol

The res: protocol is especially useful. It allows you to embed some resources like HTML pages, cascading style sheets (CSS), images (PNG, JPG etc.), javascripts into binary of your application or any DLL it uses.

All resources addressable by the control must be of type RT_HTML. This includes not just the HTML document themselves but also all their files, images, style sheets, javascript files and any other resources linked from the HTML pages, or URL passed to the control.

You can link to such resources with url in format "res://modname/res_id" where modname is name of the binary module (usually filename of your program or any DLL it loads) and res_id is ID of the resource in the resource script (RC).

Although it can be both string or number identifier, we recommend to prefer string identifiers which end with dummy "file extension", hence making a hint to the browser about the image type. Without this the browser tries to guess what type of the data the resource is, and that may be unreliable. Remember the heuristics also differ in various versions of MSIE.

For example if you have a HTML file named some_page.html and an image file image.png which can be linked from the HTML page, add the following lines into your resource script:

"some_page.html" HTML some_page.html

"image.png" HTML image.png

which is used to build a MYLIBRARY.DLL used by your application then your application can simply send the message MC_HM_GOTOURL with URL "res://mylibrary.dll/some_page.html".

Of course, HTML documents stored in the resources then can also use relative URLs to link to other documents and resources in the same module (.EXE or .DLL).

Application Protocol

MCTRL.DLL implements a simple application protocol app: which is intended for integration of HTML contents into your application logic.

Whenever user clicks on a link with URL starting with the "app:" the control sends notification MC_HN_APPLINK to its parent window which is supposed to react programatically. The control itself does not interpret application link URLs in any way.

Generated Contents

Generating HTML contents programatically is also possible to some degree. Note however that the application is not supposed to generate whole documents but only smaller snippets of them.

The application can set contents of almost any tag (identified by HTML attribute "id") with any custom string using the message MC_HM_SETTAGCONTENTS. The message takes the ID and the string as its arguments. Then, if the currently loaded page has a tag with the given ID, the content of the tag is replaced and set to the given string. Any previous content of that tag is removed. Remember the string has to follow HTML syntax and keep integrity of the HTML document.

Note the application should use the message MC_HM_SETTAGCONTENTS only after the HTML document intended to be changed is completely loaded, i.e. anytime after the notification MC_HN_DOCUMENTCOMPLETE is fired.

Attention: Please note that for limitations of Internet Explorer, contents of these tags can not be modified:
COL, COLGROUP, FRAMESET, HEAD, HTML, STYLE, TABLE, TBODY, TFOOT, THEAD, TITLE, TR.

We recommend to use tags DIV or SPAN for the dynamic contents injected by application code into the HTML pages.

Gotchas

Keep in mind that the control is relatively thin wrapper of embedded MS Internet Explorer so exact behavior depends on the version of MS IE installed.
The HTML control implementation is based on OLE and COM technologies. During creation of the control OleInitialize() is called. I.e. the OLE subsystem is initialized for every thread which creates the HTML control. OleUninitialize() is similarly called when the control is destroyed.
The value of the URL in notifications might not match the URL that was originally given to the HTML control, because the URL might be converted to a qualified form. For example, the IE sometimes adds slash ('/') after URLs having two slashes after protocol and of there is no slash after. Furthermore IE can encode some special characters into their hexadecimal representation (i.e. space ' ' becomes "%20").

Standard Messages

These standard messages are handled by the control:

CCM_GETUNICODEFORMAT
CCM_SETNOTIFYWINDOW
CCM_SETUNICODEFORMAT

These standard notifications are sent by the control:

NM_OUTOFMEMORY

Data Structures
struct	MC_NMHTMLURLW
	Structure used for notifications with URL parameter (Unicode variant). More...

struct	MC_NMHTMLURLA
	Structure used for notifications with URL parameter (ANSI variant). More...

struct	MC_NMHTMLPROGRESS
	Structure used for notification about download progress. More...

struct	MC_NMHTMLTEXTW
	Structure used for notifications with textual parameter (Unicode variant). More...

struct	MC_NMHTMLTEXTA
	Structure used for notifications with textual parameter (ANSI variant). More...

struct	MC_NMHTMLHISTORY
	Structure used for notification about history navigation. More...

Initialization Functions
BOOL	mcHtml_Initialize (void)

void	mcHtml_Terminate (void)

Window Class
#define	MC_WC_HTMLW L"mCtrl.html"

#define	MC_WC_HTMLA "mCtrl.html"

Control Styles
#define	MC_HS_NOCONTEXTMENU 0x0001
	Disables context menu. More...

Control Messages
#define	MC_HM_GOTOURLW (MC_HM_FIRST + 10)
	Displays a document specified by the given URL (Unicode variant). More...

#define	MC_HM_GOTOURLA (MC_HM_FIRST + 11)
	Displays a document specified by the given URL (ANSI variant). More...

#define	MC_HM_SETTAGCONTENTSW (MC_HM_FIRST + 12)
	Set contents of the HTML tag with given attribute `"id"` (Unicode variant). More...

#define	MC_HM_SETTAGCONTENTSA (MC_HM_FIRST + 13)
	Set contents of the HTML tag with given attribute `"id"` (ANSI variant). More...

#define	MC_HM_GOBACK (MC_HM_FIRST + 14)
	Navigates the HTML control back or forward in history. More...

#define	MC_HM_CANBACK (MC_HM_FIRST + 15)
	Tests whether going back or forward in history is possible. More...

Control Notifications
#define	MC_HN_APPLINK (MC_HN_FIRST + 0)
	Fired when the browser should navigates to to URL with application protocol. More...

#define	MC_HN_DOCUMENTCOMPLETE (MC_HN_FIRST + 1)
	Fired when loading of a document is complete. More...

#define	MC_HN_PROGRESS (MC_HN_FIRST + 2)
	Fired to inform application about download progress. More...

#define	MC_HN_STATUSTEXT (MC_HN_FIRST + 3)
	Fired when the browser would like to change status text. More...

#define	MC_HN_TITLETEXT (MC_HN_FIRST + 4)
	Fired when the browser changes title of the HTML page. More...

#define	MC_HN_HISTORY (MC_HN_FIRST + 5)
	Fired when possibility of going back or forward in history changes. More...

#define	MC_HN_NEWWINDOW (MC_HN_FIRST + 6)
	Fired when the browser would open a new window. More...

Unicode Resolution
#define	MC_WC_HTML MCTRL_NAME_AW(MC_WC_HTML)

#define	MC_HM_GOTOURL MCTRL_NAME_AW(MC_HM_GOTOURL)

#define	MC_HM_SETTAGCONTENTS MCTRL_NAME_AW(MC_HM_SETTAGCONTENTS)

#define	MC_NMHTMLURL MCTRL_NAME_AW(MC_NMHTMLURL)

#define	MC_NMHTMLTEXT MCTRL_NAME_AW(MC_NMHTMLTEXT)

Data Structure Documentation

struct MC_NMHTMLURLW

Structure used for notifications with URL parameter (Unicode variant).

See Also: MC_HN_APPLINK MC_HN_DOCUMENTCOMPLETE

Data Fields
NMHDR	hdr	Standard notification structure header.
LPCWSTR	pszUrl	String representation of the URL.

struct MC_NMHTMLURLA

Structure used for notifications with URL parameter (ANSI variant).

See Also: MC_HN_APPLINK MC_HN_DOCUMENTCOMPLETE

Data Fields
NMHDR	hdr	Standard notification structure header.
LPCSTR	pszUrl	String representation of the URL.

struct MC_NMHTMLPROGRESS

Structure used for notification about download progress.

See Also: MC_HN_PROGRESS

Data Fields
NMHDR	hdr	Standard notification structure header.
LONG	lProgress	Current progress.
LONG	lProgressMax	Progress maximum.

struct MC_NMHTMLTEXTW

Structure used for notifications with textual parameter (Unicode variant).

See Also: MC_HN_STATUSTEXT MC_HN_TITLETEXT

Data Fields
NMHDR	hdr	Standard notification structure header.
LPCWSTR	pszText	The string.

struct MC_NMHTMLTEXTA

Structure used for notifications with textual parameter (ANSI variant).

See Also: MC_HN_STATUSTEXT MC_HN_TITLETEXT

Data Fields
NMHDR	hdr	Standard notification structure header.
LPCSTR	pszText	The string.

struct MC_NMHTMLHISTORY

Structure used for notification about history navigation.

See Also: MC_HN_HISTORY

Data Fields
NMHDR	hdr	Standard notification structure header.
BOOL	bCanBack	`TRUE` if going back in history is possible.
BOOL	bCanForward	`TRUE` if going forward in history is possible.

Macro Definition Documentation

#define MC_WC_HTMLW L"mCtrl.html"

Window class name (Unicode variant).

#define MC_WC_HTMLA "mCtrl.html"

Window class name (ANSI variant).

#define MC_HS_NOCONTEXTMENU 0x0001

Disables context menu.

#define MC_HM_GOTOURLW (MC_HM_FIRST + 10)

Displays a document specified by the given URL (Unicode variant).

Parameters

	wParam	Reserved, set to zero.
[in]	lParam	(`const` `WCHAR*`) The URL.

Returns: (BOOL) TRUE on success, FALSE otherwise.

#define MC_HM_GOTOURLA (MC_HM_FIRST + 11)

Displays a document specified by the given URL (ANSI variant).

Parameters

	wParam	Reserved, set to zero.
[in]	lParam	(`const` `char*`) The URL.

Returns: (BOOL) TRUE on success, FALSE otherwise.

#define MC_HM_SETTAGCONTENTSW (MC_HM_FIRST + 12)

Set contents of the HTML tag with given attribute "id" (Unicode variant).

Parameters

[in]	wParam	(`const` `WCHAR*`) ID of the tag.
[in]	lParam	(`const` `WCHAR*`) New contents of the tag.

Returns: (BOOL) TRUE on success, FALSE otherwise.

See Also: Generated Contents

#define MC_HM_SETTAGCONTENTSA (MC_HM_FIRST + 13)

Set contents of the HTML tag with given attribute "id" (ANSI variant).

Parameters

[in]	wParam	(`const` `char*`) ID of the tag.
[in]	lParam	(`const` `char*`) New contents of the tag.

Returns: (BOOL) TRUE on success, FALSE otherwise.

See Also: Generated Contents

#define MC_HM_GOBACK (MC_HM_FIRST + 14)

Navigates the HTML control back or forward in history.

Parameters

[in]	wParam	(`BOOL`) Set to `TRUE` to go back in history or `FALSE` to go forward.
	lParam	Reserved, set to zero.

Returns: (BOOL) TRUE on success, FALSE otherwise.

See Also: MC_HM_CANBACK

#define MC_HM_CANBACK (MC_HM_FIRST + 15)

Tests whether going back or forward in history is possible.

Parameters

[in]	wParam	(`BOOL`) Set to `TRUE` to test going back in history or `FALSE` to going forward.
	lParam	Reserved, set to zero.

Returns: (BOOL) TRUE if can go back or forward respectively, FALSE otherwise.

See Also: MC_HM_GOBACK

#define MC_HN_APPLINK (MC_HN_FIRST + 0)

Fired when the browser should navigates to to URL with application protocol.

Parameters

[in]	wParam	(`int`) Id of the control sending the notification.
[in]	lParam	(MC_NMHTMLURL*) Pointer to a structure specifying details about the URL.

Returns: Application should return zero if it processes the notification.

#define MC_HN_DOCUMENTCOMPLETE (MC_HN_FIRST + 1)

Fired when loading of a document is complete.

Parameters

[in]	wParam	(`int`) Id of the control sending the notification.
[in]	lParam	(MC_NMHTMLURL*) Pointer to a structure specifying details about the URL.

Returns: Application should return zero if it processes the notification.

#define MC_HN_PROGRESS (MC_HN_FIRST + 2)

Fired to inform application about download progress.

This allows example for example to show a progress indicator.

Parameters

[in]	wParam	(`int`) Id of the control sending the notification.
[in]	lParam	(MC_NMHTMLPROGRESS*) Pointer to a structure specifying details about the progress.

Returns: Application should return zero if it processes the notification.

#define MC_HN_STATUSTEXT (MC_HN_FIRST + 3)

Fired when the browser would like to change status text.

IE usually shows this text in its status bar.

Parameters

[in]	wParam	(`int`) Id of the control sending the notification.
[in]	lParam	(MC_NMHTMLTEXT*) Pointer to a structure specifying the text.

Returns: Application should return zero if it processes the notification.

#define MC_HN_TITLETEXT (MC_HN_FIRST + 4)

Fired when the browser changes title of the HTML page.

IE usually shows this in window caption or tab label.

Parameters

[in]	wParam	(`int`) Id of the control sending the notification.
[in]	lParam	(MC_NMHTMLTEXT*) Pointer to a structure specifying the text.

Returns: Application should return zero if it processes the notification.

#define MC_HN_HISTORY (MC_HN_FIRST + 5)

Fired when possibility of going back or forward in history changes.

This allow application to enable or disable the corresponding command buttons.

Parameters

[in]	wParam	(`int`) Id of the control sending the notification.
[in]	lParam	(MC_NMHTMLURL*) Pointer to a structure specifying the text.

Returns: Application should return zero if it processes the notification.

See Also: MC_HM_GOBACK MC_HM_CANBACK

#define MC_HN_NEWWINDOW (MC_HN_FIRST + 6)

Fired when the browser would open a new window.

This happens for exaple if user clicks on a link while holding SHIFT.

MC_NMHTMLURL::pszUrl is URL to be opened in the new window. Note however that prior to Windows XP SP2, the URL is not filled.

Parameters

[in]	wParam	(`int`) Id of the control sending the notification.
[in]	lParam	(MC_NMHTMLURL*) Pointer to a structure specifying details about the URL.

Returns: Application should return non-zero to allow opening the new window, or zero to deny it.

#define MC_WC_HTML MCTRL_NAME_AW(MC_WC_HTML)

Unicode-resolution alias.

See Also: MC_WC_HTMLW MC_WC_HTMLA

#define MC_HM_GOTOURL MCTRL_NAME_AW(MC_HM_GOTOURL)

Unicode-resolution alias.

See Also: MC_HM_GOTOURLW MC_HM_GOTOURLA

#define MC_HM_SETTAGCONTENTS MCTRL_NAME_AW(MC_HM_SETTAGCONTENTS)

Unicode-resolution alias.

See Also: MC_HM_SETTAGCONTENTSW MC_HM_SETTAGCONTENTSA

#define MC_NMHTMLURL MCTRL_NAME_AW(MC_NMHTMLURL)

Unicode-resolution alias.

See Also: MC_NMHTMLURLW MC_NMHTMLURLA

#define MC_NMHTMLTEXT MCTRL_NAME_AW(MC_NMHTMLTEXT)

Unicode-resolution alias.

See Also: MC_NMHTMLTEXTW MC_NMHTMLTEXTA

Function Documentation

BOOL mcHtml_Initialize ( void )

Registers window class of the control.

Returns: TRUE on success, FALSE on failure.

void mcHtml_Terminate ( void )

Unregisters window class of the control.

Detailed Description

Resource Protocol

Application Protocol

Generated Contents

Gotchas

Standard Messages

Data Structures

Initialization Functions

Window Class

Control Styles

Control Messages

Control Notifications

Unicode Resolution

Data Structure Documentation

Macro Definition Documentation

Function Documentation