Labels are retrieved and stored when a booking is made with a carrier. The labels are stored in Google Cloud Storage together with a reference to it and some metadata in the database.
You can use the following to retrieve the available labels for a booking using the external reference of the booking.


Labels

This documentation explains how to create and customize Skrym shipping labels. It covers the layout system, required elements, and instructions for adding elements to the labels.
Label Layout System
The layout of the label is managed by a grid system that divides the label into blocks. Each block's position and size are calculated based on predefined steps.
Key Constants


Horizontal Block Sizes: These constants define the width of the blocks.

Third: Represents one-third of the page width.
Half: Represents half of the page width.
Whole: Represents the entire page width.



Vertical Steps: The height of each vertical block is fixed at 16.8 units, but this value can be configured as needed.


Positioning of label elements
calculateBlockOriginAndSize
This function calculates the origin and size of a block based on horizontal and vertical steps, block size, and its position from the left and top.
Parameters:

xSteps []float64: Array of x-axis steps that determine the horizontal positions of the blocks.
ySteps []float64: Array of y-axis steps that determine the vertical positions of the blocks.
horizontalBlockSize string: Size of the block horizontally. Possible values are:

Third: One-third of the page width.
Half: Half of the page width.
Whole: The entire page width.


blockFromLeft string: Position of the block from the left. Possible values are:

L: Left. (only applicable for third and half)
M: Middle. (only applicable for third)
R: Right. (only applicable for third and half)


blockFromTop int: Position of the block from the top (0-based index).
numberOfVerticalBlocks int: Number of vertical blocks the block spans.
pageWidth float64: The total width of the page.

Returns:

x float64: X-coordinate of the block.
y float64: Y-coordinate of the block.
width float64: Width of the block.
height float64: Height of the block.

drawGrid
Draws a grid for layout debugging.
Parameters:

pdf *fpdf.Fpdf: Pointer to the fpdf.Fpdf instance used for PDF generation.
xSteps []float64: Array of x-axis steps that determine the horizontal positions of the grid lines.
ySteps []float64: Array of y-axis steps that determine the vertical positions of the grid lines.
pageWidth float64: The total width of the page.
pageHeight float64: The total height of the page.

Adding Elements to Labels
To add elements to the label, you need to follow these steps:

Define the Block: Use calculateBlockOriginAndSize to define the position and size of the block where the element will be placed.
Draw the Element: Use the appropriate function to draw the element (e.g., imageBlock, addressBlock, contactInfoBlock).

Example: Adding a Logo
To add a logo, the following steps are taken:

Calculate the block position and size for the logo using calculateBlockOriginAndSize.
Draw the logo using imageBlock.

// Transporter logo
transporterLogoX, transporterLogoY, transporterLogoWidth, transporterLogoHeight := calculateBlockOriginAndSize(xSteps, ySteps, Third, "R", 0, 1, width)
imageBlock(pdf, transporterLogoX, transporterLogoY, transporterLogoWidth, transporterLogoHeight, transporterLogo, transportMethod.Transporter.Name, "M", "R")

List of custom label blocks
| Function                | Description                                       |
|-------------------------|---------------------------------------------------|
| calculateBlockOriginAndSize | Calculates the origin and size of a block on the label. |
| imageBlock            | Draws an image block on the label.                |
| addressBlock          | Draws an address block on the label.              |
| verticalFieldValueBlock | Draws a vertical field-value pair block.        |
| horizontalFieldValueBlock | Draws a horizontal field-value pair block.     |
| bookingDetailsBlock   | Draws booking details block containing, customer number, booking reference etc                     |
| contactInfoBlock      | Draws contact information block.                  |
| barcodeBock           | Draws a barcode block with text about the barcode content.    |