man wml::des::navbar (3): Navigation Bar

SYNOPSIS

#use wml::des::navbar
# explicitly write javascript code now
<navbar:jsfuncs>
# define a navigation bar
<navbar:define name=<name> [<options>]>
<navbar:header>...</navbar:header>
<navbar:footer>...</navbar:footer>
<navbar:prolog [<options>]>...</navbar:prolog>
<navbar:epilog [<options>]>...</navbar:epilog>
<navbar:button id=<id1> txt=... [<options>]>
:
<navbar:button id=<idN> txt=... [<options>]>
<navbar:filter>...</navbar:filter>
</navbar:define>
# debug the internal structure
<navbar:debug name=<name>>
# render the navigation bar
<navbar:render name=<name> [options]>

DESCRIPTION

This include file defines a complex navigation bar container tag named "<navbar:define>". It can be used to define navigation bars of any optical style by specifying its parts in general and individually and letting the "<navbar:render>" tag create the complete particular HTML code. Creating a navigation bar is a two step process. First you define it according to this grammar:

   navbar   ::= HEADER{0,1} 
                PROLOG{0,3} BUTTON{1,N} EPILOG{0,3} 
                FOOTER{0,1}
                FILTER{0,1}
   HEADER   ::= navbar:header
   PROLOG   ::= navbar:prolog (type=N) 
              | navbar:prolog (type=S)
              | navbar:prolog (type=SS)
   BUTTON   ::= navbar:button
   EPILOG   ::= navbar:epilog (type=N)
              | navbar:epilog (type=S)
              | navbar:epilog (type=SS)
   FOOTER   ::= navbar:footer
   FILTER   ::= navbar:filter

or in other words: navigation bar consists of an optional header and footer, up to three different (according to "type") prologs and epilogs for the navigation buttons and at least one actual navigation button. Additionally a filter can be applied. The "navbar:XXXX" names in the above grammar directly correspond to the existing tags you have to use.

After you have defined such a navigation bar (which is usually done inside an include file) you can create the corresponding HTML markup code by placing "<navbar:render>" at the point where this markup code should occur. This tag can be used more then once when you want (for instance inside a page header and its footer or once with graphics and once with the "txtonly" attribute for the textual version, etc.).

Always notice that "<navbar:render>" has no internal built-in knowledge of your navigation bar except its structure according to the above grammar. So, you only receive nice results when you define a nice grammar instance with the available "navbar:XXXX" tags. The "<navbar:render>" tag is not there to create nice things you usually couldn't do yourself. It is there to avoid the nasty compilation of one million prologs and epilogs for each button where each of these consists of similar HTML code. So, "<navbar:render>" is your workhorse, the intelligence is yours.

But how do we actually get navigation bars? Haven't we forgot something which is essential to navigation bars? Yes, we have. Navigation bars feature is that we can define them at one point for the underlaying hyperlink structure and use them at any point inside this structure while the hyperlinks are automatically aligned for the current location. But this feature the core of WML already provides through its adjustable path variables. So, this include file is useless without this feature. Or in other words: You really have to define some root-variable of your structure in a .wmlrc file and then use this variable when defining the hyperlinks inside the "<navbar:button>"'s "url" attribute. Never forget this point!

For complete examples see under "EXAMPLES" below.

OPTIONS

Options of <navbar:define>:

This defines the navigation bar.

name=STR

This sets the name of the navigation bar which is used both for internal data respresentation and for referencing in "<navbar:debug>" and "<navbar:render>". Always use this attribute (or you risk other navigation bars to be overwritten) and always use a unique name here when using more then one navigation bar.

imgstar=SPEC

This contains a colon-separated list of three strings. They are used for substitution of asterisks in the "<navbar:button>"'s "img" attribute when this attribute only contains one image filename and this filename contains an asterisk. In other words: this single image filename is expanded to a colon-separated list of three image filenames while for each filename the asterisk is substituted with the corresponding string from the "imgstar" attribute.

Example:

  <navbar:define imgstar=std:sel:ovr ...>
    ...
    <navbar:button img=button-1-*.gif ...>
    <navbar:button img=button-2-*.gif ...>
    ... 
  </navbar:define>

This is equivalent to the following:

  <navbar:define ...>
    ...
    <navbar:button img=button-1-std.gif:button-1-sel.gif:button-1-ovr.gif ...>
    <navbar:button img=button-2-std.gif:button-2-sel.gif:button-2-ovr.gif ...>
    ... 
  </navbar:define>

imgbase=PATH

Defines a common image base directory, i.e. all non-absolute pathnames in "<navbar:button>"'s "img" attributes are prefixed with PATH. Per default there is no such prefix.

urlbase=PATH

Defines a common navigation base directory, i.e. all non-absolute pathnames in "<navbar:button>"'s "url" attributes are prefixed with PATH. Per default there is no such prefix. Is is useful that PATH itself contains an WML adjustable path variable.

target=STR

The target frame or window to which all hyperlinks are per default redirected to. This can be overwritten by the "target" attribute of "<navbar:button>".

Options of <navbar:header>:

This defines the global header for the navigation bar. Currently there are no attributes used.

Options of <navbar:footer>:

This defines the global footer for the navigation bar. Currently there are no attributes used.

Options of <navbar:prolog>:

This defines the prolog of "<navbar:button>"s, i.e. the local header for each navigation button.

pos=SPEC: This sets the button position where to apply this prolog, i.e. the number of the button starting with the number 1. Use this to apply a special prolog to a particular button only. The default is "any" for SPEC which means: apply this prolog to any button as long as there is no specially defined one for it. There are three important special values for SPEC: "first" (=1), "last" (=number of used "<navbar:button>"'s) and "next" which applies to the next button only.
type=SPEC: This sets the type of application of this button. There are three possible values for SPEC: ``"N"'' (normal: used for buttons in normal state), ``"S"'' (selected: used for selected buttons) and ``"SS"'' (sub-selected: used for selected buttons but level is deeper).
This type is triggered by the "select=ID" and "subselected" attributes of "<navbar:render>".

Options of <navbar:epilog>:

This defines the epilog of "<navbar:button>"s, i.e. the local footer for each navigation button. The available attributes or the same as for "<navbar:prolog>".

Options of <navbar:button>:

This defines a particular navigation button, i.e. a text or image surrounded by a hyperlink plus a few special features like status bar hints and a rollover effect for images.

id=STR: The identification string for this button. This has to be a unique identifier which later is used with "<navbar:render>"'s "select" attribute to mark this button as selected.
alias=STR: The former "id" attribute has to be unique. This tag allows you to group buttons as if they had the same "id" attribute.
txt=STR: The textual representation of the button which is displayed. When no "alt" attribute is specified, it defaults to the value of this "txt" attribute.
alt=STR: The "alt" attribute for the created "<img>" tags. When images are not displayed this is used instead by most browsers. If images are displayed this is ignored by most browsers. It defaults to the value of the "txt" attribute.
img=SPEC: The image(s) to display for this button. This can be a single image file or a colon-separated list of three images. The first one is the normal button, the second one is the selected button variant and the third one is the variant which is displayed when the mouse is over the button (but only if the button is not a selected one).
hint=STR: The text displayed in the browsers status bar when the mouse is over the button.
url=PATH: The hyperlink URL which is activated when the button is pressed. There are three special URLs: "#UP#", "#PREV#" and "#NEXT#", which refer to the node one level up, the previous or the next node.
target=STR: A target frame or window where the hyperlink is redirected to.
menu=STR: The name of a navigation bar to insert at this point.
:a:ATTR=STR :img:ATTR=STR: The ``ATTR=STR'' pairs are passed along to the desired HTML tags. It is also possible to add a prefix to tag name to select only normal (".N"), selected (".S") or subselected (".SS") buttons.

Options of <navbar:debug>:

Use this tag while developing your navigation bar definition. It dumps the internal structure of this definition.

name=STR: The name of the navigation bar to dump. See the corresponding "name" attribute of "<navbar:define>".

Options of <navbar:render>:

name=STR

The name of the navigation bar definition to use when rendering.

select=ID

Select a particular button as selected.

subselected

Marks the selected button as a subselected one, i.e. the current page for which the button is selected is deeper than the original page for which this button stands.

txtcol_select=#rrggbb

This is a hack because of the HTML rendering of typical browsers on anchors. You have to use this attribute when you want to create textual navigations bars with specific colors, this can not be performed with prologs and epilogs when defining navbars.

txtcol_normal=#rrggbb

This is the corresponding tag to "txtcol_select" because we want to have a homogen configuration style.

menumode=inner|outer

With menumode=inner (default), a selected sub-menu is inserted before epilog of current entry, otherwise it is put after.

txtonly

Forces the rendering to ignore all defined images.

nohints

Do not create Javascript hints for navigation buttons.

:a:ATTR=STR :img:ATTR=STR

The ``ATTR=STR'' pairs are passed along to all the desired HTML tags found in this navbar. It is also possible to add a prefix to tag name to select only normal (".N"), selected (".S") or subselected (".SS") buttons. For instance with

   <navbar:render name=main :img:class=nav
      :a.N:class=nav-n :a.S:class=nav-s :a.SS:class=nav-ss />

attribute ``class=``nav'''' is added to all images, ``class=``nav-s'''' is added to anchor when button is selected (this is a dummy example, since when button is selected, there is no such anchor), ``class=``nav-ss'''' is added when button is subselected, and normal links have ``class=``nav-n''''.

Options of <navbar:filter>:

This defines the body of a Perl filtering function which can be used to post-process the generated HTML markup code before it is written out. Currently there are no attributes used.

When no "<navbar:filter>" tag is specified, no such filtering occurs. When

  <navbar:filter> BODY </navbar:filter>

is specified, internally an anonymous Perl function is created and the HTML markup code is filtered through this function as follows:

  $func = sub { BODY };
  $markup_code = &{$func}($markup_code, $CFG, $select);

where $CFG is the internal configuration structure as seen with "<navbar:debug>" and $markup_code is a literal string holding the HTML markup code. In other words, when you want to apply a filter, you have to do it with the following skeleton:

  <navbar:filter>
      my ($mcode, $CFG, $select) = @_;
      ...
      return $mcode;
  </navbar:filter>

Options of <navbar:jsfuncs>:

This prints Javascript functions used for rollover effects on images. This macro discards itself after first invocation so that definitions are printed only once. It is automatically called by "<navbar:render>", so it could looks useless. But if you consider

  <en><navbar:render name=main></en>
  <fr><navbar:render name=main></fr>

javascript code only appears in English version. The correct solution is to put this tag outside of any slice:

  <navbar:jsfuncs>
  <en><navbar:render name=main></en>
  <fr><navbar:render name=main></fr>

EXAMPLES

Classic Navigation bar

File: nb.inc

  <navbar:define name=test 
          imgbase="img/" urlbase="$(ROOT)"
          txtcol_normal="#000000" txtcol_select="#ffffff">
    <navbar:header> 
      <table cellspacing=1 cellpadding=2 border=0>
      <tr>
    </navbar:header>
    <navbar:prolog>        <td bgcolor="#cccccc"> </navbar:prolog>
    <navbar:prolog type=S> <td bgcolor="#cc3333"> </navbar:prolog>
    <navbar:button id=foo txt="Foo" url="foo.html" hint="The Foo Page"> 
    <navbar:button id=bar txt="Bar" url="bar.html" hint="The Bar Page"> 
    <navbar:button id=baz txt="Baz" url="baz.html" hint="The Baz Page"> 
    <navbar:epilog> </td> </navbar:epilog> 
    <navbar:footer> 
      </tr>
      </table> 
    </navbar:footer>
  </navbar:define>
  <navbar:render name=$(name) select=$(select)>

File: .wmlrc

  -DROOT~.
  -I.

File: foo.wml

  #use wml::std::page
  #use wml::des::navbar
  
  <page indent=2>
  #include "nb.inc" name=test select=foo
  <h1>The Foo Page</h1>
  <p>
  Foo...

File: bar.wml

  #use wml::std::page
  #use wml::des::navbar
  
  <page indent=2>
  #include "nb.inc" name=test select=bar
  <h1>The Bar Page</h1>
  <p>
  Bar...

Nested Navigation bar