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# Add-in for Programming in LibreOffice Calc

The method of extending Calc by Add-Ins that is described in the following is outdated. The interfaces are still valid and supported, to ensure compatibility with existing Add-Ins, but for programming new Add-Ins you should use the new API functions.

LibreOffice Calc can be expanded by Add-Ins, which are external programming modules providing additional functions for working with spreadsheets. These are listed in the Function Wizard in the Add-In category. If you would like to program an Add-In yourself, you can learn here which functions must be exported by the shared library external DLL so that the Add-In can be successfully attached.

LibreOffice searches the Add-in folder defined in the configuration for a suitable shared library DLL. To be recognized by LibreOffice, the shared library DLL must have certain properties, as explained in the following. This information allows you to program your own Add-In for Function Wizard of LibreOffice Calc.

## The Add-In Concept

Each Add-In library provides several functions. Some functions are used for administrative purposes. You can choose almost any name for your own functions. However, they must also follow certain rules regarding parameter passing. The exact naming and calling conventions vary for different platforms.

### Functions of Shared Library AddIn DLL

At a minimum, the administrative functions GetFunctionCount and GetFunctionData must exist. Using these, the functions as well as parameter types and return values can be determined. As return values, the Double and String types are supported. As parameters, additionally the cell areas Double Array, String Array, and Cell Array are supported.

Parameters are passed using references. Therefore, a change of these values is basically possible. However, this is not supported in LibreOffice Calc because it does not make sense within spreadsheets.

Libraries can be reloaded during runtime and their contents can be analyzed by the administrative functions. For each function, information is available about count and type of parameters, internal and external function names and an administrative number.

The functions are called synchronously and return their results immediately. Real time functions (asynchronous functions) are also possible; however, they are not explained in detail because of their complexity.

## General information about the interface

The maximum number of parameters in an Add-In function attached to LibreOffice Calc is 16: one return value and a maximum of 15 function input parameters.

The data types are defined as follows:

Data types | Definition
CALLTYPE | Under Windows: FAR PASCAL (_far _pascal) Other: default (operating system specific default)
USHORT | 2 Byte unsigned Integer
DOUBLE | 8 byte platform-dependent format
Paramtype | Platform-dependent like int PTR_DOUBLE =0 pointer to a double PTR_STRING =1 pointer to a zero-terminated string PTR_DOUBLE_ARR =2 pointer to a double array PTR_STRING_ARR =3 pointer to a string array PTR_CELL_ARR =4 pointer to a cell array NONE =5

## Shared Library DLL functions

Following you will find a description of those functions, which are called at the Shared Library external DLL.

For all Shared Library DLL functions, the following applies:

void CALLTYPE fn(out, in1, in2, ...)

Output: Resulting value

Input: Any number of types (double&, char*, double*, char**, Cell area), where the Cell area is an array of types double array, string array, or cell array.

### GetFunctionCount()

Returns the number of functions without the management functions of the reference parameter. Each function has a unique number between 0 and nCount-1. This number will be needed for the GetFunctionData and GetParameterDescription functions later.

Syntax

void CALLTYPE GetFunctionCount(USHORT& nCount)

Parameter

USHORT &nCount:

Output: Reference to a variable, which is supposed to contain the number of Add-In functions. For example: If the Add-In provides 5 functions for LibreOffice Calc, then nCount=5.

### GetFunctionData()

Determines all the important information about an Add-In function.

Syntax

void CALLTYPE GetFunctionData(USHORT& nNo, char* pFuncName, USHORT& nParamCount, Paramtype* peType, char* pInternalName)

Parameter

USHORT& nNo:

Input: Function number between 0 and nCount-1, inclusively.

char* pFuncName:

Output: Function name as seen by the programmer, as it is named in the Shared Library DLL. This name does not determine the name used in the Function Wizard.

USHORT& nParamCount:

Output: Number of parameters in AddIn function. This number must be greater than 0, because there is always a result value; the maximum value is 16.

Paramtype* peType:

Output: Pointer to an array of exactly 16 variables of type Paramtype. The first nParamCount entries are filled with the suitable type of parameter.

char* pInternalName:

Output: Function name as seen by the user, as it appears in the Function Wizard. May contain umlauts.

The pFuncName and pInternalName parameters are char arrays, which are implemented with size 256 in LibreOffice Calc.

### GetParameterDescription()

Provides a brief description of the Add-In function and its parameters. As an option, this function can be used to show a function and parameter description in the Function Wizard.

Syntax

void CALLTYPE GetParameterDescription(USHORT& nNo, USHORT& nParam, char* pName, char* pDesc)

Parameter

USHORT& nNo:

Input: Number of the function in the library; between 0 and nCount-1.

USHORT& nParam:

Input: Indicates, for which parameter the description is provided; parameters start at 1. If nParam is 0, the description itself is supposed to be provided in pDesc; in this case, pName does not have any meaning.

char* pName:

Output: Takes up the parameter name or type, for example, the word "Number" or "String" or "Date", and so on. Implemented in LibreOffice Calc as char[256].

char* pDesc:

Output: Takes up the description of the parameter, for example, "Value, at which the universe is to be calculated." Implemented in LibreOffice Calc as char[256].

pName and pDesc are char arrays; implemented in LibreOffice Calc with size 256. Please note that the space available in the Function Wizard is limited and that the 256 characters cannot be fully used.

## Cell areas

The following tables contain information about which data structures must be provided by an external program module in order to pass cell areas. LibreOffice Calc distinguishes between three different arrays, depending on the data type.

### Double Array

As a parameter, a cell area with values of the Number/Double type can be passed. A double array in LibreOffice Calc is defined as follows:

Offset | Name | Description
0 | Col1 | Column number in the upper-left corner of the cell area. Numbering starts at 0.
2 | Row1 | Row number in the upper-left corner of the cell area; numbering starts at 0.
4 | Tab1 | Table number in the upper-left corner of the cell area; numbering starts at 0.
6 | Col2 | Column number in the lower-right corner of the cell area. Numbering starts at 0.
8 | Row2 | Row number in the lower-right corner of the cell area; numbering starts at 0.
10 | Tab2 | Table number in the lower-right corner of the cell area; numbering starts at 0.
12 | Count | Number of the following elements. Empty cells are not counted or passed.
14 | Col | Column number of the element. Numbering starts at 0.
16 | Row | Row number of the element; numbering starts at 0.
18 | Tab | Table number of the element; numbering starts at 0.
20 | Error | Error number, where the value 0 is defined as "no error." If the element comes from a formula cell the error value is determined by the formula.
22 | Value | 8 byte IEEE variable of type double/floating point
30 | ... | Next element

### String Array

A cell area, which contains values of data type Text and is passed as a string array. A string array in LibreOffice Calc is defined as follows:

Offset | Name | Description
0 | Col1 | Column number in the upper-left corner of the cell area. Numbering starts at 0.
2 | Row1 | Row number in the upper-left corner of the cell area; numbering starts at 0.
4 | Tab1 | Table number in the upper-left corner of the cell area; numbering starts at 0.
6 | Col2 | Column number in the lower-right corner of the cell area. Numbering starts at 0.
8 | Row2 | Row number in the lower-right corner of the cell area; numbering starts at 0.
10 | Tab2 | Table number in the lower-right corner of the cell area; numbering starts at 0.
12 | Count | Number of the following elements. Empty cells are not counted or passed.
14 | Col | Column number of the element. Numbering starts at 0.
16 | Row | Row number of the element; numbering starts at 0.
18 | Tab | Table number of the element; numbering starts at 0.
20 | Error | Error number, where the value 0 is defined as "no error." If the element comes from a formula cell the error value is determined by the formula.
22 | Len | Length of the following string, including closing zero byte. If the length including closing zero byte equals an odd value a second zero byte is added to the string so that an even value is achieved. Therefore, Len is calculated using ((StrLen+2)&~1).
24 | String | String with closing zero byte
24+Len | ... | Next element

### Cell Array

Cell arrays are used to call cell areas containing text as well as numbers. A cell array in LibreOffice Calc is defined as follows:

Offset | Name | Description
0 | Col1 | Column number in the upper-left corner of the cell area. Numbering starts at 0.
2 | Row1 | Row number in the upper-left corner of the cell area; numbering starts at 0.
4 | Tab1 | Table number in the upper-left corner of the cell area; numbering starts at 0.
6 | Col2 | Column number in the lower-right corner of the cell area. Numbering starts at 0.
8 | Row2 | Row number in the lower-right corner of the cell area; numbering starts at 0.
10 | Tab2 | Table number in the lower-right corner of the cell area; numbering starts at 0.
12 | Count | Number of the following elements. Empty cells are not counted or passed.
14 | Col | Column number of the element. Numbering starts at 0.
16 | Row | Row number of the element; numbering starts at 0.
18 | Tab | Table number of the element; numbering starts at 0.
20 | Error | Error number, where the value 0 is defined as "no error." If the element comes from a formula cell the error value is determined by the formula.
22 | Type | Type of cell content, 0 == Double, 1 == String
24 | Value or Len | If type == 0: 8 byte IEEE variable of type double/floating point If type == 1: Length of the following string, including closing zero byte. If the length including closing zero byte equals an odd value a second zero byte is added to the string so that an even value is achieved. Therefore, Len is calculated using ((StrLen+2)&~1).
26 if type==1 | String | If type == 1: String with closing zero byte
32 or 26+Len | ... | Next element