Learn How to Generate a UPC Barcode using PHP!

Table of Contents

1. Introduction
2. Updating the Bar Position
3. Fixing the Barcode Border
4. Adding Numbers to the Label
5. Choosing the Font for the Barcode
6. Setting the Label Scale
7. Getting the Position for the Items
8. Adding Labels to the Right Positions
9. Generating the Bar Code
10. Conclusion

Updating the Bar Position

In the previous section, we initialized the bar position but did not update it, causing all the bars to be placed in the same position. To fix this, we need to update the bar position by adding the power position to it.

$barPosition = $powerPosition + $this->barWidth;

This update ensures that the bars are added in the correct position and not on top of each other.

Fixing the Barcode Border

Another issue we need to address is the appearance of the barcode border. Currently, it is not visible because we haven't instantiated it. To fix this, we can set the barcode border to a default value of 2.

$this->barcodeBorder = 2;

By assigning a value to the barcode border, we can now see the border around the barcode.

Adding Numbers to the Label

Next, let's add the numbers on the label. This step brings us closer to the final product. Before we proceed, let me introduce the font I used for the barcode. It's called "Other" and can be downloaded for free from Font Squirrel. I will provide you with the font file and its license for this tutorial. You can use this font or any other font that suits your needs.

$font = "path/to/font/other_regular.ttf";

Now, let's add the labels and numbers to the barcode. We need to consider the size and positioning of the labels. The left digits are smaller, while the middle digits are slightly larger. Moreover, the digits need to be divided into four different pieces.

To achieve this, we'll use some math calculations. Let's start by defining the scale for the outer and inner digits.

$outerDigitsScale = $this->barcodeWidth * 5;
$innerDigitsScale = $this->barcodeBorder / 0.14;

The label scale will be slightly smaller than the inner digits' scale.

$labelScale = $innerDigitsScale * 0.22;

Now that we have determined the scales, let's calculate the positions for the items on the barcode.

$digit1XYPosition = imagettfbbox($outerDigitsScale, 0, $font, $digit1);
// Calculate position for Digit 1

$digit12XYPosition = imagettfbbox($innerDigitsScale, 0, $font, $digit12);
// Calculate position for Digit 12

$labelXYPosition = imagettfbbox($labelScale, 0, $font, $label);
// Calculate position for the label

With the positions calculated, we can now proceed to add the labels to the appropriate positions based on our calculations.

Please note that for brevity, I have provided a summary of the steps involved. You can refer to the source code and the documentation for more detailed explanations.