wxWidgets/docs/doxygen/overviews/html.h
Francesco Montorsi 36c9828f70 removed useless spaces
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@51911 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
2008-02-19 13:28:24 +00:00

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/////////////////////////////////////////////////////////////////////////////
// Name: html
// Purpose: topic overview
// Author: wxWidgets team
// RCS-ID: $Id$
// Licence: wxWindows license
/////////////////////////////////////////////////////////////////////////////
/*!
@page html_overview wxHTML overview
The wxHTML library provides classes for parsing and displaying HTML.
It is not intended to be a high-end HTML browser. If you are looking for
something like that try #http://www.mozilla.org.
wxHTML can be used as a generic rich text viewer - for example to display
a nice About Box (like those of GNOME apps) or to display the result of
database searching. There is a #wxFileSystem
class which allows you to use your own virtual file systems.
wxHtmlWindow supports tag handlers. This means that you can easily
extend wxHtml library with new, unsupported tags. Not only that,
you can even use your own application-specific tags!
See @c src/html/m_*.cpp files for details.
There is a generic wxHtmlParser class,
independent of wxHtmlWindow.
@ref htmlquickstart_overview
@ref printing_overview
@ref helpformat_overview
@ref filters_overview
@ref cells_overview
@ref handlers_overview
@ref htmltagssupported_overview
@section wxhtmlquickstart wxHTML quick start
@b Displaying HTML
First of all, you must include wx/wxhtml.h.
Class #wxHtmlWindow (derived from wxScrolledWindow)
is used to display HTML documents.
It has two important methods: #LoadPage
and #SetPage.
LoadPage loads and displays HTML file while SetPage displays directly the
passed @b string. See the example:
@code
mywin - LoadPage("test.htm");
mywin - SetPage("htmlbody"
"h1Error/h1"
"Some error occurred :-H)"
"/body/hmtl");
@endcode
@b Displaying Help
See #wxHtmlHelpController.
@b Setting up wxHtmlWindow
Because wxHtmlWindow is derived from wxScrolledWindow and not from
wxFrame, it doesn't have visible frame. But the user usually wants to see
the title of HTML page displayed somewhere and the frame's titlebar is
the ideal place for it.
wxHtmlWindow provides 2 methods in order to handle this:
#SetRelatedFrame and
#SetRelatedStatusBar.
See the example:
@code
html = new wxHtmlWindow(this);
html - SetRelatedFrame(this, "HTML : %%s");
html - SetRelatedStatusBar(0);
@endcode
The first command associates the HTML object with its parent frame
(this points to wxFrame object there) and sets the format of the title.
Page title "Hello, world!" will be displayed as "HTML : Hello, world!"
in this example.
The second command sets which frame's status bar should be used to display
browser's messages (such as "Loading..." or "Done" or hypertext links).
@b Customizing wxHtmlWindow
You can customize wxHtmlWindow by setting font size, font face and
borders (space between border of window and displayed HTML). Related functions:
#SetFonts
#SetBorders
#ReadCustomization
#WriteCustomization
The last two functions are used to store user customization info wxConfig stuff
(for example in the registry under Windows, or in a dotfile under Unix).
@section printing HTML Printing
The wxHTML library provides printing facilities with several levels of complexity.
The easiest way to print an HTML document is to use
@ref htmleasyprinting_overview. It lets you print HTML documents with only one
command and you don't have to worry about deriving from the wxPrintout class at all. It is only a simple wrapper around the
#wxHtmlPrintout, normal wxWidgets printout class.
And finally there is the low level class #wxHtmlDCRenderer which you can use to
render HTML into a rectangular area on any DC. It supports rendering into multiple rectangles with the same
width. (The most common use of this is placing one rectangle on each page or printing into two columns.)
@section helpformat Help Files Format
wxHTML library uses a reduced version of MS HTML Workshop format.
Tex2RTF can produce these files when generating HTML, if you set @b htmlWorkshopFiles to @b @true in
your tex2rtf.ini file.
(See #wxHtmlHelpController for help controller description.)
A @b book consists of three files: header file, contents file and index file.
You can make a regular zip archive of these files, plus the HTML and any image files,
for wxHTML (or helpview) to read; and the .zip file can optionally be renamed to .htb.
@b Header file (.hhp)
Header file must contain these lines (and may contain additional lines which are ignored) :
@code
Contents file=filename.hhc
Index file=filename.hhk
Title=title of your book
Default topic=default page to be displayed.htm
@endcode
All filenames (including the Default topic) are relative to the
location of .hhp file.
@b Localization note: In addition, .hhp file may contain line
@code
Charset=rfc_charset
@endcode
which specifies what charset (e.g. "iso8859_1") was used in contents
and index files. Please note that this line is incompatible with
MS HTML Help Workshop and it would either silently remove it or complain
with some error. See also
@ref nonenglish_overview.
@b Contents file (.hhc)
Contents file has HTML syntax and it can be parsed by regular HTML parser. It contains exactly one list
(@c ul....@c /ul statement):
@code
ul
li object type="text/sitemap"
param name="Name" value="@topic name@"
param name="ID" value=@numeric_id@
param name="Local" value="@filename.htm@"
/object
li object type="text/sitemap"
param name="Name" value="@topic name@"
param name="ID" value=@numeric_id@
param name="Local" value="@filename.htm@"
/object
...
/ul
@endcode
You can modify value attributes of param tags. @e topic name is name of chapter/topic as is displayed in
contents, @e filename.htm is HTML page name (relative to .hhp file) and @e numeric_id is optional
- it is used only when you use wxHtmlHelpController::Display(int)
Items in the list may be nested - one @c li statement may contain a @c ul sub-statement:
@code
ul
li object type="text/sitemap"
param name="Name" value="Top node"
param name="Local" value="top.htm"
/object
ul
li object type="text/sitemap"
param name="Name" value="subnode in topnode"
param name="Local" value="subnode1.htm"
/object
...
/ul
li object type="text/sitemap"
param name="Name" value="Another Top"
param name="Local" value="top2.htm"
/object
...
/ul
@endcode
@b Index file (.hhk)
Index files have same format as contents file except that ID params are ignored and sublists are @b not
allowed.
@section filters Input Filters
The wxHTML library provides a mechanism for reading and displaying
files of many different file formats.
wxHtmlWindow::LoadPage can load not
only HTML files but any known file. To make a file type known to wxHtmlWindow
you must create a #wxHtmlFilter filter and
register it using wxHtmlWindow::AddFilter.
@section cells Cells and Containers
This article describes mechanism used by
#wxHtmlWinParser and
#wxHtmlWindow to parse and display HTML documents.
@b Cells
You can divide any text (or HTML) into small fragments. Let's call these
fragments @b cells. Cell is for example one word, horizontal line, image
or any other part of document. Each cell has width and height (except special
"magic" cells with zero dimensions - e.g. colour changers or font changers).
See #wxHtmlCell.
@b Containers
Container is kind of cell that may contain sub-cells. Its size depends
on number and sizes of its sub-cells (and also depends on width of window).
See #wxHtmlContainerCell,
wxHtmlCell::Layout.
This image shows the cells and containers:
@b Using Containers in Tag Handler
#wxHtmlWinParser provides a user-friendly way
of managing containers. It is based on the idea of opening and closing containers.
Use #OpenContainer to open new
a container @e within an already opened container. This new container is a
@e sub-container of the old one. (If you want to create a new container with
the same depth level you can call @c CloseContainer(); OpenContainer();.)
Use #CloseContainer to close the
container. This doesn't create a new container with same depth level but
it returns "control" to the parent container.
See explanation:
There clearly must be same number of calls to OpenContainer as to
CloseContainer.
@b Example
This code creates a new paragraph (container at same depth level)
with "Hello, world!":
@code
m_WParser - CloseContainer();
c = m_WParser - OpenContainer();
m_WParser - AddText("Hello, ");
m_WParser - AddText("world!");
m_WParser - CloseContainer();
m_WParser - OpenContainer();
@endcode
and here is image of the situation:
You can see that there was an opened container before the code was executed.
We closed it, created our own container, then closed our container and opened
new container. The result was that we had @e same depth level after
executing. This is general rule that should be followed by tag handlers:
leave depth level of containers unmodified (in other words, number of
OpenContainer and CloseContainer calls should be same within #HandleTag's body).
Notice that it would be usually better to use
wxHtmlContainerCell::InsertCell instead
of adding text to the parser directly.
@section handlers Tag Handlers
The wxHTML library provides architecture of pluggable @e tag handlers.
Tag handler is class that understands particular HTML tag (or tags) and is
able to interpret it.
#wxHtmlWinParser has static table of @b modules.
Each module contains one or more tag handlers. Each time a new wxHtmlWinParser
object is constructed all modules are scanned and handlers are added
to wxHtmlParser's list of available handlers (note: wxHtmlParser's list
is non-static).
@b How it works
Common tag handler's #HandleTag method
works in four steps:
Save state of parent parser into local variables
Change parser state according to tag's params
Parse text between the tag and paired ending tag (if present)
Restore original parser state
See #wxHtmlWinParser for methods for modifying
parser's state. In general you can do things like opening/closing containers,
changing colors, fonts etc.
@b Providing own tag handlers
You should create new .cpp file and place following lines into it:
@code
#include mod_templ.h
#include forcelink.h
FORCE_LINK_ME(yourmodulefilenamewithoutcpp)
@endcode
Then you must define handlers and one module.
@b Tag handlers
The handler is derived from #wxHtmlWinTagHandler
(or directly from #wxHtmlTagHandler)
You can use set of macros to define the handler (see src/html/m_*.cpp files
for details). Handler definition must start with @b TAG_HANDLER_BEGIN macro
and end with @b TAG_HANDLER_END macro. I strongly recommend to have a look
at @e include/wxhtml/mod_templ.h file. Otherwise you won't understand
the structure of macros. See macros reference:
@b TAG_HANDLER_BEGIN(@e name, @e tags)
Starts handler definition. @e name is handler identifier (in fact
part of class name), @e tags is string containing list of tags
supported by this handler (in uppercase). This macro derives new class from
wxHtmlWinTagHandler and implements it is
#GetSupportedTags method.
Example: TAG_HANDLER_BEGIN(FONTS, "B,I,U,T")
@b TAG_HANDLER_VARS
This macro starts block of variables definitions. (Variables are identical
to class attributes.) Example:
@code
TAG_HANDLER_BEGIN(VARS_ONLY, "CRAZYTAG")
TAG_HANDLER_VARS
int my_int_var;
wxString something_else;
TAG_HANDLER_END(VARS_ONLY)
@endcode
This macro is used only in rare cases.
@b TAG_HANDLER_CONSTR(@e name)
This macro supplies object constructor. @e name is same name as the one
from TAG_HANDLER_BEGIN macro. Body of constructor follow after
this macro (you must use and ). Example:
@code
TAG_HANDLER_BEGIN(VARS2, "CRAZYTAG")
TAG_HANDLER_VARS
int my_int_var;
TAG_HANDLER_CONSTR(vars2)
{ // !!!!!!
my_int_var = 666;
} // !!!!!!
TAG_HANDLER_END(VARS2)
@endcode
Never used in wxHTML :-)
@b TAG_HANDLER_PROC(@e varib)
This is very important macro. It defines #HandleTag
method. @e varib is name of parameter passed to the method, usually
@e tag. Body of method follows after this macro.
Note than you must use and ! Example:
@code
TAG_HANDLER_BEGIN(TITLE, "TITLE")
TAG_HANDLER_PROC(tag)
{
printf("TITLE found...\n");
}
TAG_HANDLER_END(TITLE)
@endcode
@b TAG_HANDLER_END(@e name)
Ends definition of tag handler @e name.
@b Tags Modules
You can use set of 3 macros TAGS_MODULE_BEGIN, TAGS_MODULE_ADD and
TAGS_MODULE_END to inherit new module from
#wxHtmlTagsModule and to create instance of it.
See macros reference:
@b TAGS_MODULE_BEGIN(@e modname)
Begins module definition. @e modname is part of class name and must
be unique.
@b TAGS_MODULE_ADD(@e name)
Adds the handler to this module. @e name is the identifier from
TAG_HANDLER_BEGIN.
@b TAGS_MODULE_END(@e modname)
Ends the definition of module.
@b Example:
@code
TAGS_MODULE_BEGIN(Examples)
TAGS_MODULE_ADD(VARS_ONLY)
TAGS_MODULE_ADD(VARS2)
TAGS_MODULE_ADD(TITLE)
TAGS_MODULE_END(Examples)
@endcode
@section htmltagssupported Tags supported by wxHTML
wxHTML is not full implementation of HTML standard. Instead, it supports most common tags so that it
is possible to display @e simple HTML documents with it. (For example it works fine with pages created
in Netscape Composer or generated by tex2rtf).
Following tables list all tags known to wxHTML, together with supported parameters.
A tag has general form of @c tagname param_1 param_2 ... param_n where param_i is
either @c paramname="paramvalue" or @c paramname=paramvalue - these two are equivalent. Unless stated
otherwise, wxHTML is case-insensitive.
@b Table of common parameter values
We will use these substitutions in tags descriptions:
@code
[alignment] CENTER
LEFT
RIGHT
JUSTIFY
[v_alignment] TOP
BOTTOM
CENTER
[color] HTML 4.0-compliant colour specification
[fontsize] -2
-1
+0
+1
+2
+3
+4
1
2
3
4
5
6
7
[pixels] integer value that represents dimension in pixels
[percent] i%
where i is integer
[url] an URL
[string] text string
[coords] c(1),c(2),c(3),...,c(n)
where c(i) is integer
@endcode
@b List of supported tags
@code
A NAME=[string]
HREF=[url]
TARGET=[target window spec]
ADDRESS
AREA SHAPE=POLY
SHAPE=CIRCLE
SHAPE=RECT
COORDS=[coords]
HREF=[url]
B
BIG
BLOCKQUOTE
BODY TEXT=[color]
LINK=[color]
BGCOLOR=[color]
BR ALIGN=[alignment]
CENTER
CITE
CODE
DD
DIV ALIGN=[alignment]
DL
DT
EM
FONT COLOR=[color]
SIZE=[fontsize]
FACE=[comma-separated list of facenames]
HR ALIGN=[alignment]
SIZE=[pixels]
WIDTH=[percent|pixels]
NOSHADE
H1
H2
H3
H4
H5
H6
I
IMG SRC=[url]
WIDTH=[pixels]
HEIGHT=[pixels]
ALIGN=TEXTTOP
ALIGN=CENTER
ALIGN=ABSCENTER
ALIGN=BOTTOM
USEMAP=[url]
KBD
LI
MAP NAME=[string]
META HTTP-EQUIV="Content-Type"
CONTENT=[string]
OL
P ALIGN=[alignment]
PRE
SAMP
SMALL
STRIKE
STRONG
SUB
SUP
TABLE ALIGN=[alignment]
WIDTH=[percent|pixels]
BORDER=[pixels]
VALIGN=[v_alignment]
BGCOLOR=[color]
CELLSPACING=[pixels]
CELLPADDING=[pixels]
TD ALIGN=[alignment]
VALIGN=[v_alignment]
BGCOLOR=[color]
WIDTH=[percent|pixels]
COLSPAN=[pixels]
ROWSPAN=[pixels]
NOWRAP
TH ALIGN=[alignment]
VALIGN=[v_alignment]
BGCOLOR=[color]
WIDTH=[percent|pixels]
COLSPAN=[pixels]
ROWSPAN=[pixels]
TITLE
TR ALIGN=[alignment]
VALIGN=[v_alignment]
BGCOLOR=[color]
TT
U
UL
@endcode
*/