Monkeybread Software - DynaPDF Manual

DynaPDF Manual - Page 533

Function Reference

Page 533 of 839

Human readable text

Many barcodes consist of the barcode and a human readable text portion that is mostly drawn

below the barcode. In image mode it is possible to adjust the font size and font weight with the flags

bcoSmallText and bcoBoldText. More options are not available in image mode.

In vector mode, we have more control over the text. The default font for text is the standard font

Helvetica but it is possible to change it to an arbitrary font by setting the flag bsoUseActiveFont.

When this flag is set the active font is used to output the text. This font should be loaded with the

code page cp1252 or cpUnicode. If no font is active the function falls back again to Helvetica. This font

is always available unless it was disabled with SetUseStdFonts() or SetFontSearchOrder(). Note that

the function fails with a fatal error if no font can be loaded when text must be drawn.

The function tries to achieve an almost identical result in comparison to the image version of a

barcode. This required a bit fine tuning by adjusting the font size and vertical text position. The font

size scaling factor (member FSizeFactor) is set to 0.7 by default but it can be set to values between 0.3

through 3.0. However, the text cannot become wider as the barcode. The font size will be decreased

if the text does not fit into the barcode width. Setting the scaling factor to an unneccesary large value

increases the processing time.

The vertical text position can be adjusted with the member TextOffsetY.

Outer border

The member OuterBorder can be used to extend the background rectangle. Each side of OuterBorder

specifies the line width of the corresponding side of the rectangle. OuterBorder is measured in user

space whereas BorderWidth is measured in pixels of the reference grid (see Scaling Details below).

Note that the background rectangle is drawn only if BgColor is set to another value than

NO_COLOR (default).

Scaling details

Barcodes are rendered internally to a virtual integer raster that we call reference grid. Although the

width and height of the reference grid is mostly unknown, the height of lines or bars of 1D codes

can be controlled with the member SymbHeight and the amount of space between bars can be

adjusted with SpaceWidth. Both values are measured in pixels of the reference grid.

The default symbol height of 1D barcodes is 50. The default space width is just zero since

meaningful values depend on the barcode type.

The full height of a 1D barcode is the height of the bars plus optional text, that is mostly drawn

below the code. The default font size is 8 for image based barcodes and 9 for vector based barcodes.

Although not every part of a barcode can be scaled freely, with SymbHeight and SpaceWidth it is

possible to control the proportions of a barcode precise enough to achieve reasonable results.