Programming custom calculations in Table controls (prefix syntax)

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Programming custom calculations in Table controls (prefix syntax)

Overview

How to?

Exporting the results of calculations

See also

Programming custom calculations in Table controls (prefix syntax)

Overview

WINDEV allows you to easily insert automatic calculations into the columns found in the Table and TreeView Table controls.

From version 22, you also have the ability to perform automatic calculations in the columns found in the Table and TreeView Table controls. These calculations are performed through programming.

How to?

Implementation

To add a custom calculation in the column of a Table control (or TreeView Table), use <Table>.FormulaAdd.

This function expects as parameter:

the name of the column taken into account for the calculation.
the caption of the row that displays the calculation in the Table control. If this caption does not exist, the row will be created. If this caption exists, the calculation will be displayed in the requested column.
the name of three procedures. These procedures are used to:
- initialize the calculation,
- to perform a calculation for each row of the Table control,
- perform the final calculation if necessary.

Example:

TABLE_MyTable.FormulaDeleteAll()
nRow is int
nRow = TABLE_MyTable.COL_Num.FormulaAdd("Positive mean", ProcInit, ProcAdd, ProcEnd)
// Change the background color of the row for custom calculation
COL_Num[nRow].BackgroundColor = LightRed

nCounter is int
INTERNAL PROCEDURE ProcInit()
nCounter = 0
RESULT 0
END

INTERNAL PROCEDURE ProcAdd(Accumulator, ColValue)
// Ignores the negative numbers or NULL
IF (ColValue <= 0) RESULT Accumulator
nCounter++
RESULT Accumulator + ColValue
END
INTERNAL PROCEDURE ProcEnd(Accumulator)
IF nCounter = 0 THEN RESULT 0
// Calculate the mean
RESULT Accumulator/nCounter
END

Remarks:

The custom calculation rows are automatically recalculated as soon as the content of the Table or TreeView Table control changes.
Tip: The iteration procedure is called for each row: we advise you not to perform slow calculations (avoid the accesses to the database for example).
The TotalsEnabled property does not allow or forces automatic or custom calculations in a Table control.
If the DisplayEnabled property is used on the Table control and is set to False, the column calculations are not updated.
The following syntax is used to retrieve the value of the custom calculation for a column:

<Table control>.<Column name>[Row number]

where <Row number> is the row index returned by <Table>.FormulaAdd.

Position of calculation row

To configure the position of automatic or custom column calculations:

Go to the "General" tab of the Table control (to do so, select the name of the Table control and click "General").
Specify the location of totals. To display the results:
- in one or more rows directly added after the last control row, check "In the table, after the last row".
  These rows are visible:
  - at the bottom of the Table control if the control includes no vertical scrollbar.
  - when the vertical scrollbar is located at the very bottom if the Table control includes a vertical scrollbar.
- below the Table control, check "Below the table".
  These rows are always visible.
- you also have the ability to perform column calculations without displaying them ("No display" option).
Validate the Table control description window.

Customizing the calculation row

You have the ability to customize (caption, color, font, height, ...):

the added row by using the following syntax:

<Table control>[Row number].<Property> = <New value>
the cell containing the result by using the following syntax:

<Table control>.<Column name>[Row number].<Property> = <New value>

Caution: the first column contains the caption of the calculation if it exists.

where:

<Row number> is the row index returned by <Table>.FormulaAdd.

<Property> can correspond to one of the following properties:


BackgroundColor	Used to find out and modify the background color of a calculation cell.
Caption	Used to find out and modify the caption of the row containing a calculation cell.
Color	Used to find out and modify the color of the text displayed in a calculation cell.
Font	Allows you to find out and modify the font used in a calculation cell.
FontBold	Used to find out and modify the "Bold" attribute for the column elements.
FontCondensed	Used to find out whether the characters of column elements are condensed or not, and to condense (or not) the characters of column elements.
FontExtended	Used to find out whether the characters of column elements are extended or not, and to extend (or not) the characters of column elements.
FontItalic	Used to find out and modify the "Italic" attribute for the column elements.
FontLarge	Used to find out whether the characters of column elements are enlarged or not, and to enlarge (or not) the characters of column elements.
FontName	Used to find out and modify the font used for the column elements.
FontSize	Used to find out and modify the size of the font used for the column elements.
FontStrikeOut	Used to find out and modify the "StrikeOut" attribute for a calculation cell.
FontUnderlined	Used to find out and modify the "Underline" attribute for the column elements.
Height	Used to find out and modify the height of a calculation cell.
Name	Used to find out the name of a calculation cell.
Note	Used to find out and modify the notes associated with a calculation cell.
State	Gets and changes the display state of the row containing the calculation cell.
Visible	Used to find out whether a column is visible and to make a column visible/invisible.
Width	Used to find out and modify the width of a calculation cell.

Deleting the custom calculation rows

To delete the custom calculation rows, use <Table>.FormulaDeleteAll.

Exporting the results of calculations

Export via the AAF (Automatic Application Features) of Table control

The context menu of Table and TreeView Table controls contains several options to export the control content.

During this export, the results of custom calculations are exported.

Remark: Only the value is exported, not the caption.

Export via the WLanguage functions

Several WLanguage functions can be used to export the content of a Table control in a specific format (Word, Excel, XML, ...). During this export, the rows corresponding to calculations are also exported by default.

To avoid exporting the calculation rows, all you have to do is specify the taNoTotal constant in the following functions:


<Table>.ToClipboard	Copies the content of a Table or TreeView Table control to the clipboard.
<Table>.ToExcel	Creates an Excel file with the data from a Table or TreeView Table control.
<Table>.ToText	Creates a character string from the data found in a Table or TreeView Table control.
<Table>.ToWord	Creates a Word file (.RTF) from the data found in a Table or TreeView Table control.
<Table>.ToXML	Creates an XML file from the data found in a Table or TreeView Table control.