Widgets

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Revision as of 08:14, 2 April 2015 by Hraban (talk | contribs) (example for setting default values with JS)
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< Visuals | Interaction >

You can find more about interactive form elements in Widgets uncovered. It’s written for MkII, but still mostly valid.

At the moment all of the following examples are from mwidget manual. We will cook up our own later.

JavaScript

If you need to check or otherwise process the input of your forms, you need JavaScript to handle interaction. For simple forms without input validation, you can skip this section.

\startJSpreamble {name}
MyCounter = 0 ;
\stopJSpreamble

\startJScode {increment}
MyCounter = MyCounter + 1 ; // or: ++MyCounter ;
\stopJScode

\goto {advance by one} [JS(increment)]

Beware, in MkIV (as of 2015-04-01) the JS code is only copied to the PDF if there is a \goto referencing one of the defined functions!

You can pass values to a JS function:

\startJScode {increment}
MyCounter = MyCounter + JS_V_1 ;
\stopJScode

\goto {advance by five} [JS(increment{V{5}})]
  • V{} is verbose, defaults to string
  • S{} = as string
  • R{} = as reference
  • JS_V_n, JS_S_n, JS_R_n are the names of the variables
  • JS_N keeps the number of arguments

Documentation

JavaScript in Acrobat is different than in a web context. Documentation is even more sparse that on ConTeXt ;) Debugging is only possible in Acrobat Pro, and also there very inconvenient. Additionally, Acrobat’s possibilities change with every version.

Examples

Setting a default value

Here we set a date field to the current date on opening the document. Additionally we have a button that can hide/show a form field.

\starttext
\setupinteraction	[state=start]

\startJSpreamble
var d = new Date();
var df = this.getField("CurDate");
df.value = util.printd("dd.mm.yyyy", d);

function toggleField(){
	var f = this.getField("CurDate");
	f.display = ! f.display;
}
\stopJSpreamble

% this button makes no sense for the example, but in MkIV we need one \goto,
% otherwise we get no JS into the PDF
\goto{toggle}[JS(toggleField)]
\blank

\setupfield[shortString][reset,horizontal][height=5mm, width=50mm, frame=off, bottomframe=on]
\definefield[CurDate][line][shortString][][JavaScript should replace this text with the current date]

Current date: \field[CurDate]

\stoptext

Fields


Someone thinks this entry needs some more explanation. (See: Needs Explanation?, To-Do List.)


Relevant commands:

Field types:

  • line: one line of text
  • text: more lines of text
  • radio: radiobutton (only one of a group can be active)
  • check: checkbox

Beware, for fillinfields in MkIV you need \usemodule[fields]! They’re meant for clozes (texts with gaps, like in questionnaires).

In MkIV (as of 2015-04-01) default values are always used verbatim, i.e. JS() doesn’t work.

Other fields you must first define and then use. That might look complicated, but you can use the same field several times, and the contents will automatically repeat themselves if you need the same content at several places, even on different pages.

Text Entries

\fillinfield[name]{text that defines field length}

or

\setupfield[ShortLine][horizontal][width=2cm]
\definefield [Email] [line] [ShortLine] [] [sample@contextgarden.net]
\field [Email] [your email]

Radiobuttons

Sample from the manual:

\setupfield [LogoSetup]
        [width=4cm,
        height=4cm,
        frame=off,
        background=screen]

\definefield[Logos] [radio] [LogoSetup][ConTeXt,PPCHTEX,TeXUtil] [PPCHTEX]

\definesubfield [ConTeXt] [] [ConTeXtLogo]
\definesubfield [PPCHTEX] [] [PPCHTEXLogo]
\definesubfield [TeXUtil] [] [TeXUtilLogo]

\definesymbol [ConTeXtLogo] [{\externalfigure[mpcont.502]}]
\definesymbol [PPCHTEXLogo] [{\externalfigure[mpcont.503]}]
\definesymbol [TeXUtilLogo] [{\externalfigure[mpcont.504]}]

\hbox to \hsize{\hss\field[ConTeXt]\hss\field[PPCHTEX]\hss\field[TeXUtil]\hss}

Checkboxes

\setupfield[setup 3]
        [width=2cm, height=2cm,
        rulethickness=3pt, corner=round, framecolor=red]

\definesymbol [yes] [{\externalfigure[mpcont.502]}]
\definesymbol [no] []
\definefield [checkme][check] [setup 3] [yes,no] [no]
\field[checkme]

Tricks

This helps debugging (MkII only!):

\tracefieldstrue
\showfields  % typeset a table of field relations
\logfields     % logs field descriptions to a file fields.log

Samples