iXPos (Function)

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Origin and physical margins

Managing the parameter

Combining positions ( parameter)

Printing in Java and Android

See also

iXPos (Function)

In french: iPosX

Allows you to manage the horizontal position (X coordinate) of print cursor in the page. You can:

find out the current horizontal position,
modify the horizontal position of print cursor.

Remark: When printing a character string, the current vertical position points to the top of the string to print. The bottom print line depends on the height of the fonts used in the printed line.

Example

// Draw vertical lines separated by two millimeters
// across the entire page width
iVLine(0, iPageHeight(), 1) // Draws a line
iXPos(iXPos() + 2) // Shifts by 2
iVLine(0, iPageHeight(), 3) // Draws a line
iEndPrinting()

Syntax

Finding out the horizontal position of print cursor Hide the details

<Result> = iXPos()

<Result>: Real

Current horizontal position of cursor (in millimeters).

Modifying the horizontal position of print cursor Hide the details

<Result> = iXPos(<Horizontal position> [, <Immediate calculation>])

<Result>: Character string

Requested horizontal position.

<Horizontal position>: Real

New horizontal position (X coordinate) of print cursor (in millimeters).

<Immediate calculation>: Optional boolean

True (by default) to immediately calculate the horizontal position.
False if the horizontal position must be calculated during the print (when nesting positions for example). See remarks for more details.

Remarks

Origin and physical margins

The origin (0,0) is located in the top left corner of the sheet. This origin takes the physical printer margins into account.

Each printer includes physical margins in which no printing is possible. iMargin is used to define the "logical" print margins. If logical margins have been defined, iXPos manages the horizontal position according to these new margins.

Managing the <Immediate Calculation> parameter

When <Horizontal Position> is specified in iXPos, the function performs two actions at the same time:

Returns a control character string. This control character string modifies the print position when the string is printed.
Immediately modifies the position of print cursor

The <Immediate Calculation> parameter is used to retrieve the control character string without modifying the current position of print cursor

sMyTitle is string = "Print title"
iDestination(iViewer)

// --- CASE 1: <Immediate Calculation> is set to True (default)
// Position the cursor at requested location
// Note: The control character string is not retrieved here
iXPos((iPageWidth() - iTextWidth(sMyTitle))/2)
// Calculation to center the text

// Print at cursor position (defined beforehand)
iPrint(sMyTitle) // Must be centered

// --- CASE 2: The same code with <Immediate Calculation> set to False
// The control character string is not retrieved here
// And the print cursor is not positioned because
// <Immediate Calculation> is set to False
// Note: Therefore, this line is not required
iXPos((iPageWidth() - iTextWidth(sMyTitle))/2, False)

// Print at cursor position
// As the previous code line did not change it
// the text will be printed at the previous position (at the beginning of line)
iPrint(sMyTitle) //Therefore MUST NOT be centered

// --- CASE 3: A single code line
// With <Immediate Calculation> set to True or to False
// the result is the same

// The position of the print cursor is modified when
// running iXPos, and when printing the
// character string that contains the result returned by iXPos
iPrint(iXPos((iPageWidth() - iTextWidth(sMyTitle))/2, True) + sMyTitle)
// Must be centered
// The positioning is done twice: a little bit longer
// but the result is the expected one

// --- CASE 3 B
// The position of print cursor IS NOT modified when
// running iXPos, BUT it is modified when
// printing the character string that contains the result
// returned by iXPos
iPrint(iXPos((iPageWidth() - iTextWidth(sMyTitle))/2, False) + sMyTitle)
// Must be centered

// End of print
iEndPrinting()

Combining positions (<Immediate Calculation> parameter)

When combining positions, unexpected results may occur. For example, the following code:

iXPos(50)
iPrint("First part" + iXPos(20) + "Second part")

is not equivalent to:

iPrint(iXPos(50) + "First part" + iXPos(20) + "Second part")

In the first case, the entire character string is printed at horizontal position 20. Indeed, in this case, the function iXPos(20) is executed during the construction of the chain to be printed and thus before the printing of the chain "First part".

To get an identical result, all you have to do is use iXPos with the False parameter: iXPos(20, False) will only be run during the print.

The same operation can be performed by iYPos.

Printing in Java and Android

The prints can be less precise because the print resolution is set to 72 dot per inch (dpi) even if the printer supports higher resolutions.

Consequence: The calculations of points in images and in drawings (lines for example) are rounded during the position calculations when printing, especially for small values. During the print, the calculations are performed in point (according to the print resolution) instead of mm (or cm).

Example: Printing lines: if the spacing between the lines is set to 0.5 mm, how many points will be found between each line (resolution set to 72 ppp)?

The first line is positioned at 0.5 mm which means (0.5/25.4) inches with a resolution of 72 points per inch (ppp): (0.5/25.4) x 72 = 1.42 point. The point being the base unit, it cannot be divided: the result is automatically rounded to 1 point less or greater according to the case.

This is a succession of lines printed with a spacing set to 05 mm:

0.5 mm --> (1.42) 1 point
1.0 mm --> (2.84) 3 points
1.5 mm --> (4.25) 4 points. Caution: the line found at 1.5 mm is stuck to the line found at 1 mm (no spacing between these two lines)
2.0 mm --> (5.67) 6 points
2.5 mm --> (7.09) 7 points. Caution: the line found at 2.5 mm is stuck to the line found at 2 mm (no spacing between these two lines)
3.0 mm --> (8.50) 9 points
3.5 mm --> (9.92) 10 points. Caution: the line found at 3.5 mm is stuck to the line found at 3 mm (no spacing between these two lines)
4.0 mm --> (11.33) 11 points. Caution: the line found at 4 mm is stuck to the line found at 3.5 mm (no spacing between these two lines)
etc.

To get a proper representation (no rounding), the size and/or the position in mm for a resolution set to 72 ppp must be a multiple of 127/360.

1 point --> (1/72) pouces --> (1/72) x 25.4 mm = 127/360 = 0.3527778 mm

Component: wd260prn.dll