Why is Code 128 not displayed correctly in JavaFX TextFlow?

Question

I'm currently creating a program where the user gives a text as input, and then gets displayed the same text with the Code 128 font to see his input as a barcode.

I already installed and located Code 128 and Code 39 under /usr/share/fonts/truetype/

Both fonts should be installed correctly because both work in Libre Office Writer. However, only Code 39 is displayed correctly in my JavaFx Application.

That's my code:

package sample;

import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.TextArea;
import javafx.scene.control.TextField;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
import javafx.scene.text.TextFlow;
import javafx.stage.Stage;

public class CreateBarcodeStage extends Stage {

VBox vbox;

TextField textFieldInput;
TextFlow textFlowOutput;

public CreateBarcodeStage() {
    createUI();
    this.setTitle("Create Barcode");
    this.setScene(new Scene(vbox));
}

private void createUI() {
    vbox = new VBox(10);

    textFieldInput = new TextField();
    textFieldInput.textProperty().addListener((ObservableValue<? extends String> observableValue, String s, String t1) -> {
        String inputText = textFieldInput.getText();

        textFlowOutput.getChildren().clear();

        Text textReadable = new Text();
        textReadable.setFont(Font.font("Verdana", 20));
        textReadable.setText(inputText + "\n\n");

        Text textBarcode = new Text();
        textBarcode.setFont(Font.font("Code 128", 40));
        textBarcode.setText(inputText);

        textFlowOutput.getChildren().addAll(textReadable, textBarcode);
    });
    textFlowOutput = new TextFlow();
    textFlowOutput.setPadding(new Insets(15));
    textFlowOutput.setPrefWidth(200);
    textFlowOutput.setPrefHeight(150);


    vbox.getChildren().addAll(textFieldInput, textFlowOutput);

}
}

If I replace "Code 128" with "Code 39" everthing works fine.

This is the output with Code 39:

Code 39 output

And here is the output with Code 128:

Code 128 output

I don't know why Code 128 isn't displayed correctly.

EDIT: Ok, so now I tried to add an asterix before and after the Code 39 text and in this case everything works. I tested it with a barcode scanner app on my smartphone and the result was right.

For Code 128 I enhanced my code with a checksum maker which I found on github: github Code 128 barcode generator

Now my code looks like this:

package sample;

import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.TextArea;
import javafx.scene.control.TextField;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
import javafx.scene.text.TextFlow;
import javafx.stage.Stage;

public class CreateBarcodeStage extends Stage {
VBox vbox;

TextField textFieldInput;
TextFlow textFlowOutput;

public CreateBarcodeStage() {
    createUI();
    this.setTitle("Create Barcode");
    this.setScene(new Scene(vbox));
}

private void createUI() {
    vbox = new VBox(10);

    textFieldInput = new TextField();
    textFieldInput.textProperty().addListener((ObservableValue<? extends String> observableValue, String s, String t1) -> {
        String inputText = textFieldInput.getText();

        textFlowOutput.getChildren().clear();

        Text textReadable = new Text();
        textReadable.setFont(Font.font("Verdana", 20));
        textReadable.setText(inputText + "\n\n");

        Text textBarcode = new Text();
        textBarcode.setFont(Font.font("Code 128", 40));
        textBarcode.setText(inputText);

        textFlowOutput.getChildren().addAll(textReadable, textBarcode);
    });
    textFlowOutput = new TextFlow();
    textFlowOutput.setPadding(new Insets(15));
    textFlowOutput.setPrefWidth(200);
    textFlowOutput.setPrefHeight(150);


    vbox.getChildren().addAll(textFieldInput, textFlowOutput);

}

private String createCode128(String text) {
    return (char) 136 + text + checksum(text) + (char) 138;
}

char checksum(String text) {
    int result = 104; // Code 128B start code
    for (int i = 0; i < text.length(); i++) {
        result += ((int) text.charAt(i) - 32) * (i + 1);
    }
    return (char) (result % 103 + 32); // Return the character value of the checksum.
    }
}

However, it still doesn't work: Code 128 with start/stop symbol and checksum

The only thing I can think of is the font is not 100% barcode symbols. For some reason your Code 128 font is mapping ASCII codes to human-readable characters and they've buried their bar symbols in high ASCII. Personally, I think it is a poor design decision to create a barcode font that requires unicode or high ASCII ($80-$FF) to work, but actually has symbols for the human-readable characters. Have you brought the font up in mapping software so you can see all the characters? — Brian Anderson, Nov 11 '17 at 01:02

score 0 · Answer 1 · answered Nov 10 '17 at 20:51

While the output may look fine using the Code 39 font, it isn't. It will not scan and is not recognizable as a Code 39 barcode. This is what the word "TEXT" looks like in Code 39:

And this is what "TEXT" looks like with Code 128:

It looks like, with Code 39, you are missing the start and stop characters because what you are displaying in the Code 39 example is actually a subset of the bars, like so:

I suspect that with Code 128, you might not be supplying the start, stop and checksum characters, and the render is failing because of it.

Also, check to make sure you are passing low ASCII ($00-$7F) characters to Code 128. The font might not work with UTF-8 or UTF-16. Check the font's documentation. — Brian Anderson, Nov 11 '17 at 00:53

Why is Code 128 not displayed correctly in JavaFX TextFlow?

1 Answers1