Multipart Preview Now Supports TrimBox and More

What this article covers

This article explains how the Multipart Preview feature has been enhanced to support multiple PDF page box types, giving you more control over how artwork is displayed in the preview window.
You’ll learn what’s changed, why it matters, and how to configure which page box (TrimBox, CropBox, BleedBox, ArtBox, or MediaBox) defines your multipart previews.

About this feature

Previously, multipart previews were always generated using the MediaBox area of a PDF, which represents the full physical page including bleed and trim areas.
In this release, you can now specify which page box to use when generating multipart previews — providing a more accurate and consistent view of how your artwork will appear after trimming or finishing.

This enhancement benefits production teams that rely on precise on-screen previews to validate layout, bleed, and cropping accuracy before printing.

What’s included

• New configuration option: previewPageBoxOption in multipart product setup.

• Support for the following PDF page box types:

  • TrimBox – The final trimmed page area.

  • CropBox – The visible portion after cropping.

  • BleedBox – The area including bleed beyond the trim line.

  • ArtBox – The content or artwork area.

  • MediaBox – The full physical page (default).

• Backward compatibility: defaults to MediaBox if no value is set.

Key settings

• previewPageBoxOption
  Found in the multipart configuration XML of a product.
  Defines which page box to use when generating the on-screen preview.
  Example values:

  previewPageBoxOption="TrimBox" previewPageBoxOption="CropBox" previewPageBoxOption="BleedBox" previewPageBoxOption="ArtBox" previewPageBoxOption="MediaBox"

• Preview Rendering Logic
  Determines how the chosen box influences the displayed artwork boundaries.

Use cases

• Proofing accuracy: Show only the final trimmed content (TrimBox) to reflect the printed outcome.

• Artwork inspection: Use BleedBox or CropBox to verify margins and bleed.

• Template verification: Match previews with designer expectations from Adobe or PitStop.

• Consistency: Ensure preview and print align exactly, reducing prepress errors.

Step-by-step implementation

Step 1 – Edit your multipart product

1. Go to Admin → Catalog → Products.

2. Click Edit on the multipart product you want to configure.

3. Scroll to the multipart configuration area.

Step 2 – Update the configuration XML

1. Locate or add the previewPageBoxOption attribute in your multipart setup.

<?xml version="1.0" encoding="utf-8" ?>
<Configuration previewPageBoxOption="ENTER VALUE HERE"  previewModeType="minimumdummypages" editorMode="required" confirmPreview="False">
   <Parts>
       <PartConfiguration type="userupload" name="upload" requiredCheckProfile="" optionalFixProfile=""  />
   </Parts>
   <InputItems>
       <InputItem type="part">
           <ItemInfo>
                   <InternalName>upload</InternalName>
                   <UIName>Upload a PDF</UIName>
                   <UIDescription>Upload PDF files for printing</UIDescription>
           </ItemInfo>
           <ItemContent>
                   <PartName>upload</PartName>
                   <Usage type="range" min="1" max="5" />
           </ItemContent>
       </InputItem>
   </InputItems>
   <Order>
      <OrderItem>upload</OrderItem>
   </Order>
</Configuration>

1. Enter the desired value (e.g., TrimBox, CropBox, BleedBox, ArtBox, or MediaBox).

2. Save your changes.

💡 If no value is specified, MediaBox will continue to be used as the default for backward compatibility.

Step 3 – Test the preview

1. Open the product in the storefront.

2. Generate a preview and inspect the visible area.

3. Confirm that the preview now matches the expected region of the PDF (for example, trimmed vs. full bleed).

Step 4 – Validate output

1. Compare the on-screen preview with your production-ready file.

2. Ensure that what appears in the preview corresponds to the correct box definition.

3. Adjust as needed for different artwork templates or production workflows.

Tips & best practice

• Use TrimBox for accurate visual proofing of finished product size.

• Use BleedBox when validating print-ready files that require bleed margins.

• Always coordinate with your design or prepress teams to match their PDF export settings.

• Test multiple files to confirm consistent preview scaling across different formats.