VkWebViewerBase(3)VkWebViewerBase(3)NAMEVkWebViewerBase - 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
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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.
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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.
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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.
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