How to create a 2D barcode as a vector image?

Question

Java

I'm generating 2D barcodes using the iText API, but they end up as bitmaps in the PDF document, and the quality of the barcode degrades when printed on low resolution printers. As a result, these barcodes cannot be scanned. Here is our code:

BarcodePDF417 pdf417 = new BarcodePDF417();
String text = "BarcodePDF417 barcode";
pdf417.setText(text);
Image img = pdf417.getImage();        
document.add(img);

We take a method placeBarcode()to create a vector image. We tried to use it like this:

Rectangle pageSize = new Rectangle(w * 72, h * 72);
Document doc = new Document(pageSize, 1f, 1f, 1f, 1f);
PdfWriter writer = PdfWriter.getInstance(doc, getOutputStream());
doc.open();
PdfContentByte cb = writer.getDirectContent();
BarcodePDF417 pf = new BarcodePDF417();
pf.setText("BarcodePDF417 barcode");
Rectangle rc = pf.getBarcodeSize();
pf.placeBarcode(cb, BaseColor.BLACK, rc.getHeight(), rc.getWidth());
doc.close();

As a result, the page becomes completely black.

Answer 1

See the BarcodePlacement example. Here we generate three PDF417 barcodes:

Image img = createBarcode(1, 1, pdfDoc);
doc.add(new Paragraph(String.format("This barcode measures %s by %s user units",
    img.getImageScaledWidth(), img.getImageScaledHeight())));
doc.add(img);
img = createBarcode(3, 3, pdfDoc);
doc.add(new Paragraph(String.format("This barcode measures %s by %s user units",
    img.getImageScaledWidth(), img.getImageScaledHeight())));
doc.add(img);
img = createBarcode(3, 1, pdfDoc);
doc.add(new Paragraph(String.format("This barcode measures %s by %s user units",
    img.getImageScaledWidth(), img.getImageScaledHeight())));
doc.add(img);

The result looks like this:
Barcodes
This is what one of the barcodes looks like inside:
Vector data
I'm adding an inside view to show that the 2D barcode is not being added as a bitmap (as in your example). This is a vector image that consists of a group of small rectangles. You can check it yourself in barcode_placement.pdf
file Object Imageshould not confuse you. If you look at the method createBarcode(),you will see what Imageis actually a vector image:

public Image createBarcode(float mw, float mh, PdfDocument pdfDoc) {
    BarcodePDF417 barcode = new BarcodePDF417();
    barcode.setCode("BarcodePDF417 barcode");
    return new Image(barcode.createFormXObject(Color.BLACK, pdfDoc)).scale(mw, mh);
}

The height and width passed through the method scale()determine the height and width of the small rectangles. On the inside of the barcode, you can see the following:
This is a rectangle that has x = 0, y = 21, width is 3, and height is -1.
When you ask for the barcode size, you get the number of rectangles needed. The barcode dimensions will be calculated as follows:

Rectangle size = barcode.getBarcodeSize();
float width = mw * size.getWidth();
float height = mh * size.getHeight();

You assume that the value of size (size in user units) is true only if mwand are mhequal to 1.
I use the values ​​to create an example PdfFormXObjectand move it to Image. I can then add Imageto the document just like any other image. The main difference between this image and the usual ones is that it is vector.