VkWebViewerBase(3)

NAME
     VkWebViewerBase - Web viewing component

INHERITS FROM
     VkComponent, wvBrowser : VkCallbackObject

HEADER FILE
     #include <Vk/VkWebViewer.h>

PUBLIC PROTOCOL SUMMARY
   Constructor/Destructor
           VkWebViewerBase(const char *, VkComponent)
           VkWebViewerBase(const char *, Widget)
           VkWebViewerBase(const char *)
           ~VkWebViewerBase();


   Accessing URLs and Files
           void fetchUrl(const cstring& url, const cstring& query,
                      const cstring& method, NavigationFlags nav);
           void fetchFile(const cstring& filename, NavigationFlags nav);


   Loading control
           void stopFetch()


   Miscellaneous
           void setFollowLinks(Boolean f)
           Boolean getFollowLinks()
           void notify(NotifyReason, const char* message);
           void postError(const char*)



CLASS DESCRIPTION
     This viewkit component provides a means for application which would like
     to provide web access from within the application. Many reasons for
     providing such access may have little to do with the web "per se."  For
     example, this component can be used with a form and the post method to
     obtain a license for a user from a local or remote server. The component
     can be used to format text and images in a purely read-only fashion, or
     could be used to provide help to the user. See also VkWebViewer.

     This component complies with the HTML level 3.2 specification. Tables are
     supported fully (excepting decimal alignment),  and some Netscape
     extensions are supported,  including FRAMES and partial support for the
     CENTER tag and various attributes such as background images and colors
     for text.

     The 2.0 version added support for tables, frames and the semantics for
     IMG and TABLE where LEFT and RIGHT alignments flow the remaining text
     around. Additions in the 3.0 version include CSS1 stylesheets,
     JavaScript, plugins (o32 only), animated gifs, authentication, cookies,
     and additional small bits of tags and attributes.

     In this version,  the superclass of the ViewKit components is wvBrowser,
     and many methods have been moved upward into the wvBrowser superclass.
     Note that it is somewhat more tricky to work with this since we're using
     C++ multiple inheritence.  Note that the library version has been
     incremented since the interface changes can not be made in a binary
     compatible fashion.  Developers who've overriden methods in
     VkWebViewerBase would be well advised to examine wvBrowser and override
     the equivalent methods there.  Application programmers who've use the
     ViewKit components unchanged should not have any issues after
     recompilation.

     Methods which have new virtuals in wvBrowser which should be used for
     proper override include.  One general tendency is to use the string class
     defined in /usr/include/CC/mstring.h to pass parameters.  The moved
     methods include:


   activate
     Override the activate(const cstring& url, ...) method instead.

   gotoUrl
     fetchUrl is slightly more functional.

   loadFile
     fetchFile

   findWindowTarget
     findTargetBrowser - You must override this instead.  findWindowTarget can
     now only be used as a call interface.  Overriding it will not produce any
     effect.

   notify
     You should preferentially override the notify(NotifyReason, const char*)
     version of this method. notify(const char*) is kept for source
     compatibility.

   stopTransfer
     Call or override stopFetch instead.  You may continue to call
     stopTransfer from an application.


     There have been other semantic changes.  Caching interfaces are no longer
     available as caching is in the websupport ism and cannot be
     programmatically controlled. The user can control global caching behavior
     with the controlpanel supplied.  Navigation is now supported for any
     wvBrowser object,  although only VkWebViewer supplies a builtin GUI.  To
     use navigation with VkWebViewerBase as a toplevel frame,  create a
     wvNavigator object with the toplevel frame's browser as the argument.
     Other public include files now exist for the wvNavigator and wvBrowser
     objects, and previous public objects are now in their own wvObjects.h
     include file.

     Several methods in the public include file, dumpDocument and
     dumpStructure are primarily included for our own debugging use,  but may
     prove interesting to curious programmers who want to know how the data is
     stored internally for the HTML documents and rendering structures.


   Web sites
     Web sites which may be of interest to the user of this component or the
     VkWebViewer subclass:


           Web consortium:
              http://www.w3.org/
           Web consortium style sheet information:
              http://www.w3.org/Style
           VRML information:
              http://vrml.wired.com/vrml.tech/
           HTML specs at the W3 consortium:
              http://www.w3.org/hypertext/WWW/MarkUp/html-spec/html-spec.txt
           Yahoo WWW HTML list:
              http://www.yahoo.com/Computers/World_Wide_Web/HTML/
           Style sheets for SGML:
              http://www.falch.no/~pepper/DSSSL-Lite/
           Word processor file filters for HTML:
              http://www.w3.org/hypertext/WWW/Tools/Word_proc_filters.html
           Netscape's HTML extensions:
              http://home.netscape.com/assist/net_sites/html_extensions.html
           SGML on the Web:
              http://www.ncsa.uiuc.edu/SDG/Software/Mosaic/WebSGML.html



FUNCTION DESCRIPTIONS
   void fetchUrl(const cstring& url, const cstring& query,
                 const cstring& method, NavigationFlags = NAV_NONE)
     This is a wvBrowser method and should be used in place of gotoLink.  Main
     method used to load a URL. The method is normally "GET". "POST" is
     generally used for form queries. NavigationFlags advise the browser as to
     whether this load is the result of navigation and will not normally be
     used by a calling application.


   void fetchFile(const cstring& filename, NavigationFlags = NAV_NONE)
     This is a wvBrowser method and should be used in place of loadFile.  This
     may be thought of as a functional equivalent of fetchUrl for the given
     filename as a file: url.

   void stopFetch()
     This is a wvBrowser method and should be used in place of stopTransfer.
     Stops the current transfer in progress. This can be called at anytime,
     even if there is no transfer in progress. This also sets flags to abort
     the loading of any images or other associated files which are currently
     in progress.  Note that this only will apply to loading associated with
     the object this is called with.


   void setFollowLinks(Boolean flag)
     If this is set to False (default in the base class,  True is the default
     for VkWebViewer) then the user clicking on a link will not cause the
     viewer to follow the link to show the new page.


   Boolean getFollowLinks()
     Obtain the value of the flag for following links.


   time_t getDefaultExpiration()
     Returns the value of the defaultExpiration.


   void postError(const char* message)
     Posts message in an error dialog as a convenience to the programmer.


Bugs and Limitations
     Although the viewer loads the page and images asynchronously,  the user
     interface must still become unavailable during the initial network lookup
     of the web site being accessed.  This is,  at the moment,  unavoidable
     and a problem for all browsers.

     Although FTP sites can be accessed,  only viewable items should be
     followed by the user.  Other items,  such as binary files,  will be
     downloaded,  but there is no mechanism for saving them.

     This man page does not truly supply sufficient information for
     subclassers.