zintBarcode

Introduction

zintBarcode provides a VFP connector to the Zint Barcode Generator library.

Zint is an open source project that implements 1D and 2D barcode symbologies. The VFP connector uses the zint.dll library to access the Zint API, and it's compatible with versions 2.10 to 2.13 (the last one, at the time of writing).

Developers should refer to the Zint documentation for a presentation on the library (Read The Fine Manual).

In particular, zintBarcode implements the following Zint API methods:

Zint API	ZintBarcode connector	Feature
ZBarcode_Encode_And_Print	EncodeSave	Generates a barcode and saves it to a file
ZBarcode_Encode	Encode	Generates a barcode
ZBarcode_Print	Save	Saves a generated barcode to a file

zintBarcode also implements getters and setters for all input properties of the Zint Symbol structure (and getters for the others).

See zintBarcode Classes for further documentation.

The Zint API is discussed in the Section 5 of the manual. The settings that control the generation process are described in point 5.6.

A description of the available symbologies and specific settings for them is presented in Section 6.

Additionally, zintBarcode implements a high-level method that returns the name of a barcode image file. The name can be used as a Picture or Control Source in VFP reports and forms. See the demo section below, for an example of both scenarios.

As an extension to the original library, zintBarcode supports the placement of image overlays on top of the generated barcodes. The demo section also presents a sample case.

Setup

zintBarcode comes as a single program file, but depends on the Zint Dynamic Link Library, as well as on the VFP2C32 Fox Link Library.

Both should be downloaded from their sites (Zint project; VFP2C32 project). For convenience, binary copies of both libraries are stored in this repository.

To overlay an image on the barcode, the GdiPlusX library must be present in the application environment.

zintBarcode is implemented as a class, and to put its definition in scope the command

DO zintbarcode.prg

should be issued. Afterward,

LOCAL ZB AS ZintBarcode

m.ZB = CREATEOBJECT("ZintBarcode")

will instantiate a zintBarcode object.

Quick demo

In this demo, a QR code is produced and displayed in the VFP's main screen.

Install the library and its dependencies:

DO LOCFILE("zintbarcode.prg")

Instantiate a zintBarcode object:

m.ZB = CREATEOBJECT("ZintBarcode")

Encode a QR barcode:

m.ZB.SetSymbology(58)
m.ImgFilename = m.ZB.ImageFile("https://vfpx.github.io")

Create an image object in the VFP _Screen:

_Screen.AddObject("qr", "Image")

Load the barcode into the image:

_Screen.qr.Picture = m.ImgFilename

Display the image

_Screen.qr.Visible = .T.

Demos

zintBarcode in a form

A simple Code 128 generator form. The barcode is regenerated as the user types new text. This is the code for the text control InteractiveChange event:

Thisform.Image1.Picture = Thisform.zs.ImageFile(This.Value, "gif")
Thisform.Text2.Value = Thisform.zs.GetErrorText()

To run the demo:

DO FORM demo\code128generator

zintBarcode in a report a)

A Northwind Catalog of current products. The Id can be selected by scanning a barcode.

The barcode image is set when the report cursor is populated (a field in the cursor holds the filename).

SELECT cpl.ProductId, ;
		cpl.ProductName, ;
		m.ZB.Imagefile(TRANSFORM(cpl.ProductId)) AS barcode ;
	FROM Northwind!Current_Product_List cpl ;
	INTO CURSOR curReport

To run the demo:

DO demo\northwindCatalog.prg

zintBarcode in a report b)

A report of current VFPX projects. A program fetches the data from the VFPX website, including the URL of the projects, and builds a report for the resulting cursor. The URLs are represented as QR codes (their colors depending on the project status).

A PRIVATE variable ZS points to a zintBarcode object that generates the QR for each project. A Picture control source in the report is set to the method that returns the name of the image file for each project's URL.

To run the demo:

DO demo\vfpxprojects.prg

Barcodes with overlay images

Images can be placed over barcodes of any symbology. Since the readability of the barcode may be seriously affected, comprehensive testing is highly recommended.

Overlay images may be used to add a logo to a barcode, or to comply with a requirement imposed by an organization.

Overlay images may be dropped on a barcode as they are, or resized to fit a specific width and height.

In the demo, a report on the sessions of the Virtual Fox Fest produces QR codes with links to the sessions. Each QR code includes a photo of the speaker at its center.

The code section that controls the overlay image:

* use a VFP image as the overlay image
m.ZB.SetOverlay(m.ZB.Photo)
* the size
m.ZB.SetOverlayWidth(34)	&& 30x39, 4 pixels for the margin
m.ZB.SetOverlayHeight(43)
* and a margin
m.ZB.SetOverlayMargin(2)
* isometric resizing (it's the default, anyway)
m.ZB.SetOverlayIsometric(.T.)
* and placed at the center (also the default)
m.ZB.SetOverlayPosition("C")

* the subclassing of ZintBarcode
DEFINE CLASS ZintBarcodeExtended AS ZintBarcode

	ADD OBJECT Photo AS Image

	PROCEDURE DynamicSettings (InputData AS String)

		This.Photo.PictureVal = curVFFSessions.photo   && a blob in a cursor

	ENDPROC

ENDDEFINE

The report:

To run the demo:

DO demo\virtualfoxfest.prg

Licensing and acknowledgments

Unlicensed.

Zint is Copyright © 2023 Robin Stuart, distributed under a BSD license.

VFP2C32 by Christian Ehlscheid with collaboration of Eric Selje.

GdiPlusX by Bernard Bout (project manager) et al.

Status

In development.