LibreOffice Javascript

There are other languages in which you can write LibreOffice macros. One of them is Javascript. If you’ve installed the package “libreoffice-script-provider-js”, you can write Javascript macros. In Linux’ you can use apt-get or rpm to install it.

Javascript macros can be edited from LibreOffice, and is ready to run without compilation.

.In the Developer Guide, you will find how to write macros in Java. Those example can be easily translated to Javascript. You can even implement interfaces and extend classes. For example, you can override an “actionPerformed” method of a button, as shown in the previous postLibreOffice – The Kakuro Cell Macro.

LibreOffice provides you with a friendlier way to create dialogs:

1. Tools=>Macros=>Organize Dialogs.

2. Edit an existing dialog or a new one.

3. If you added a control, such as a button, double-click it. a window is opened. In the General Tab, you can get or change information such as the name (important if you want to use it in the macro), color, type (“Ok” button, for example), etc. In the Event tab, you can assign macros to events.

The dialog can be created and executed by a macro. Following is an example in LibreOffice Basic:

Sub kakuro_cell
DialogLibraries.LoadLibrary( “Standard” )

oDialog1 = CreateUnoDialog( DialogLibraries.Standard.kakuro )

oDialog1.Execute()
End Sub

This will show the following dialog:

Clicking “Submit” will run another macro with the event details, and the “Button type” selected in the general tab was “OK”. We can also start our macro by pressing the “tab” key until our button gains focus and then pressing the Enter key, thus the event starting the macro is “Item status change”.

Now, what does event handling look like in a Javascript macro:

 event=ARGUMENTS[0];      // Because this macro is a callback, it has the event for first argument.
 evtSource=event.Source;       // The control that fired the event.
 xControl=UnoRuntime.queryInterface(XControl, evtSource);
 xControlModel = xControl.getModel();
 xPropertySet = UnoRuntime.queryInterface(XPropertySet, xControlModel);
 peer=xControl.getPeer();       // The dialog window.
 ctx=xControl.getContext();
 ctxControlContainer=UnoRuntime.queryInterface(XControlContainer, ctx);  // Yes, the window is a control container that contains the button and input fields.
 lowerPartControl = ctxControlContainer.getControl("lowerPart");
 lowerPartModel=lowerPartControl.getModel();
 lowerPartPropertySet=UnoRuntime.queryInterface(XPropertySet,
                                                lowerPartModel);
 upperPartControl = ctxControlContainer.getControl("upperPart");
 upperPartModel=upperPartControl.getModel();
 upperPartPropertySet=UnoRuntime.queryInterface(XPropertySet,
                                                upperPartModel);

How to Translate from Java to Javascript?

The interpreter used by the script provider is named Rhino, an interpreter developed by Mozilla.  Rhino is written entirely in Java, and allows developers to embed Java objects within their code.

Importing

To embed a Java object, you should first import it using the command “importClass(Packages.<class-name>);”.

For example:

importClass(Packages.com.sun.star.sheet.XSpreadsheetDocument);

XSCRIPTCONTEXT

In Javascript, the first command executed is not found inside a function, so instead of an argument of class XScriptContext, a variable named XSCRIPT CONTEXT is supplied upon invocation of a Javascript macro.

Java Objects

Java objects are accessed the same way in both Java and Javascript, but without the casting in the latter because Javascript is loosely type. The “new” command in Javascript has the same syntax as in Java, except for instantiating a Java array.

Instantiating a Java Array

A Javascript array containing Java objects is not a Java array. To instantiate a Java array, you should use class “java.lang.reflect.Array”. This class and other classes from the “reflect” package should not be imported.

To instantiate an array use the function “newInstance(<class>, <integer array>);”. For example:
points = java.lang.reflect.Array.newInstance(Point, [1, 3]);
Will create a bi-dimensional array with one row and 3 columns of Point objects.

Implementing an Interface or Extending a Class

Use the syntax:

<var> = new <class or interface>(<args>){
      <func-name>: function(<args>){
     }
}

For example:

xButton.addActionListener(new XActionListener() {
                    
     disposing: function(evtObj) {
        // TODO Auto-generated method stub
                        
     }
      
     actionPerformed: function(evt){
        // Javascript code
        .
        .
        .
     }
}


JSON, The New XML

When you write for the web, you may want to send data to another server or to a client. A common way to transfer that data is in XML format. The data will then be processed using SAX, DOM or XPath. Every language support it.

If what you want is to define a variable, an object or an array in Javascript, you can use the JSON extension. JSON is an acronym for ‘Java Script Object Notation’. In Javascript you can use it as follows:

var myObject=<?php echo json_encode($php_object); >;

Here no parsers are required.

Here’s an example of using it in PHP:

<?
class my_class {
  public $prop1;
  public $prop2;

  function __construct(){
    $this->prop1='a';
    $this->prop2=400;
  }
}

$obj=new my_class();
echo json_encode($obj);
?>

The output looks like:
{“prop1″:”a”,”prop2″:400}

In addition to encoding, a JSON string can be decoded into an object in a language other than Javascript. Thus, you can pass data in the JSON format to any program supporting JSON, and, as you can see in www.json.org, most languages used today support it.

The ability to encode varibles into JSON and decode it back in any language is not the only reason why JSON can replace XML. If you go to www.json.org, you can see links in the bottom referring to other sites. For example, JSONPath, that allows you to access a member just like XPath. JSONPath is available in PHP and Javascript.