Split PDF Pages in PHP: Create Half-Sized Pages Without Blank Space

Splitting PDF pages in PHP requires using specialized libraries like FPDF, TCPDF, or mPDF to create half-sized pages without blank space. The key is calculating exact content boundaries and creating pages that match the actual dimensions of each section rather than using full page heights. For invoice-specific splitting, you’ll need to identify the Y coordinate where the invoice section begins and create two separate pages with appropriate dimensions.

Contents

• Understanding PDF Page Splitting in PHP
• Best PHP Libraries for PDF Manipulation
• Step-by-Step Guide to Splitting PDF Pages in Half
• Removing Blank Space from Split PDF Pages
• Advanced Techniques for Invoice-Specific PDF Splitting

Understanding PDF Page Splitting in PHP

PDF page splitting in PHP involves taking a single page and dividing its content into multiple smaller pages. When working with invoices, this typically means separating the header or content above the invoice from the actual invoice section. The challenge lies in not just visually splitting the content, but creating actual half-sized pages that match the exact dimensions of the content they contain.

Unlike simple PDF viewers that might just overlay content on full-sized pages, proper page splitting requires:

1. Identifying the exact boundary between sections
2. Creating new pages with dimensions proportional to the content
3. Copying content to these new pages with proper scaling
4. Removing any remaining blank space

This process differs from basic PDF manipulation because it’s not just about extracting pages, but about creating new, properly-sized pages that contain only the relevant content. For invoice processing, this ensures that each resulting page contains only the information needed without unnecessary whitespace.

The “keep invoice” function you’re using likely identifies where the invoice content begins on the page, but the issue is that it’s still creating full-sized pages rather than resizing them to match the actual content dimensions.

Best PHP Libraries for PDF Manipulation

Several PHP libraries can help you split PDF pages effectively. Each has its strengths and weaknesses when it comes to page manipulation and content extraction:

FPDF (Free PDF)

FPDF is a lightweight PHP library focused on PDF generation. While it doesn’t have built-in page splitting functionality, it offers precise control over page dimensions and content positioning. With FPDF, you can create half-sized pages by setting the page dimensions and positioning content exactly where you need it. The library’s SetPage() method allows you to create new pages, and you can calculate the exact Y coordinate where your invoice begins to split the content accordingly.

TCPDF

TCPDF is a more comprehensive library that provides advanced page manipulation features. It offers methods like setPage() and SetSourceFile() that make it particularly suitable for extracting specific content areas and creating split pages. TCPDF’s ability to calculate content boundaries precisely makes it ideal for removing blank space from resulting pages. The library’s support for page templates and content positioning gives you fine control over how content is divided between pages, making it well-suited for invoice-specific splitting requirements.

mPDF

mPDF excels at HTML-to-PDF conversion and offers flexible page manipulation options. For splitting pages in half, you can use the SetDisplayMode() and SetPageOrientation() methods to control page layout. mPDF’s content analysis capabilities can help identify content boundaries, making it easier to remove blank space. The library’s support for CSS positioning and page breaks is particularly useful for dividing content between pages based on logical sections like invoice headers and details.

PDF Parser Libraries

For more advanced splitting, consider using PDF parser libraries that can extract content coordinates and boundaries. These libraries analyze the PDF structure to determine where content actually begins and ends, allowing you to create pages that match the exact content dimensions rather than using full page heights.

Each library has its advantages, but TCPDF often provides the most comprehensive features for page splitting and content boundary detection, making it a good choice for your invoice splitting needs.

Step-by-Step Guide to Splitting PDF Pages in Half

Here’s a practical approach to splitting PDF pages in half using PHP:

Step 1: Install the Chosen Library

First, install your preferred PDF library via Composer:

composer require tecnickcom/tcpdf

Step 2: Load the Original PDF

use setasign\Fpdi\Fpdi;

$pdf = new Fpdi();
$pageCount = $pdf->setSourceFile('your_invoice.pdf');

Step 3: Identify the Split Point

Determine the Y coordinate where your invoice section begins. This might be based on content analysis or known positioning:

$splitY = 120; // Example Y coordinate where invoice begins

Step 4: Create the First Page (Above Invoice)

Create a new page with dimensions matching the content above the invoice:

// Import the first page
$templateId = $pdf->importPage(1);

// Get page dimensions
$pageSize = $pdf->getTemplateSize($templateId);

// Create first page with reduced height
$pdf->AddPage('P', [$pageSize['width'], $splitY]);

// Copy content to the first page
$pdf->useTemplate($templateId, 0, 0, $pageSize['width'], $splitY);

Step 5: Create the Second Page (Invoice Section)

Create another page for the invoice section:

// Create second page with remaining height
$pdf->AddPage('P', [$pageSize['width'], $pageSize['height'] - $splitY]);

// Copy invoice content to the second page
$pdf->useTemplate($templateId, 0, -$splitY, $pageSize['width'], $pageSize['height']);

Step 6: Save the Result

$pdf->Output('split_invoice.pdf', 'F');

This approach creates two pages with actual half-sized dimensions rather than full pages with blank space. The key is calculating the exact split point and creating pages that match the content dimensions rather than using default page sizes.

Removing Blank Space from Split PDF Pages

The main issue you’re facing—blank space in the resulting pages—typically occurs when pages are created with standard dimensions rather than matching the actual content. Here’s how to remove that blank space:

Calculate Content Boundaries

Instead of using arbitrary split points, analyze the actual content to determine where it begins and ends:

// Get the bounding box of content on the page
$bbox = $pdf->getTemplateBbox($templateId);

// Calculate split point based on content
$splitY = $bbox['h'] * 0.6; // Split at 60% of content height

Create Pages with Exact Content Dimensions

Create pages that match the exact dimensions of the content they contain:

// First page dimensions match content above split
$pdf->AddPage('P', [$bbox['w'], $splitY]);

// Second page dimensions match remaining content
$pdf->AddPage('P', [$bbox['w'], $bbox['h'] - $splitY]);

Use Proper Scaling and Positioning

Ensure content is scaled and positioned correctly to avoid blank areas:

// Copy content with proper scaling
$pdf->useTemplate($templateId, 0, 0, $bbox['w'], $splitY, false, false, 0, $splitY);

// For the second page, adjust the Y offset
$pdf->useTemplate($templateId, 0, -$splitY, $bbox['w'], $bbox['h'], false, false, 0, 0);

Trim Margins

If your PDF has margins that are creating blank space, you can trim them by adjusting the page creation:

// Calculate trim box dimensions
$trimBox = [
 'x' => $bbox['x'],
 'y' => $bbox['y'],
 'w' => $bbox['w'],
 'h' => $bbox['h']
];

// Create pages with trimmed dimensions
$pdf->AddPage('P', [$trimBox['w'], $splitY - $trimBox['y']]);

By implementing these techniques, you’ll create pages that contain only the relevant content without unnecessary blank space, resulting in properly half-sized pages that match the actual dimensions of your invoice sections.

Advanced Techniques for Invoice-Specific PDF Splitting

For more sophisticated invoice splitting, consider these advanced techniques:

Content-Based Splitting

Instead of using a fixed Y coordinate, analyze the content to identify where the invoice section begins:

// Analyze text content to find invoice section
$text = $pdf->extractText(1);
$invoicePosition = strpos($text, 'Invoice #');

if ($invoicePosition !== false) {
 // Calculate approximate Y coordinate based on text position
 $splitY = $invoicePosition / 50; // Adjust based on your font size
}

Template-Based Splitting

Create templates for different invoice layouts to ensure consistent splitting:

// Define invoice templates
$templates = [
 'standard' => ['splitY' => 120, 'headerHeight' => 80],
 'compact' => ['splitY' => 100, 'headerHeight' => 60]
];

// Use appropriate template based on PDF characteristics
$template = $this->detectInvoiceTemplate($pdf);
$splitY = $templates[$template]['splitY'];

Multi-Document Output

Create separate documents for different sections rather than just splitting pages:

// Create header document
$headerPdf = new Fpdi();
$headerPdf->AddPage('P', [$width, $splitY]);
$headerPdf->useTemplate($templateId, 0, 0, $width, $splitY);
$headerPdf->Output('invoice_header.pdf', 'F');

// Create invoice document
$invoicePdf = new Fpdi();
$invoicePdf->AddPage('P', [$width, $height - $splitY]);
$invoicePdf->useTemplate($templateId, 0, -$splitY, $width, $height);
$invoicePdf->Output('invoice_details.pdf', 'F');

Automated Invoice Detection

Implement automated detection to identify invoice sections across different PDFs:

function detectInvoiceSection($pdf) {
 // Check for invoice keywords
 $invoiceKeywords = ['invoice', 'bill', 'receipt', 'tax'];
 $text = $pdf->extractText(1);
 
 foreach ($invoiceKeywords as $keyword) {
 $position = stripos($text, $keyword);
 if ($position !== false) {
 return $position;
 }
 }
 
 return false; // Default split position
}

Batch Processing

Process multiple invoices at once with consistent splitting:

function batchSplitInvoices($directory) {
 $files = glob($directory . '/*.pdf');
 
 foreach ($files as $file) {
 $pdf = new Fpdi();
 $templateId = $pdf->setSourceFile($file);
 $splitY = $this->detectInvoiceSection($pdf);
 
 // Split logic here
 $this->splitInvoice($pdf, $templateId, $splitY, $file);
 }
}

These advanced techniques will help you create a robust invoice splitting system that works consistently across different PDF layouts and removes blank space effectively.

Sources

1. FPDF Documentation — Comprehensive guide to PHP PDF generation and manipulation: https://www.fpdf.org/en/doc/
2. TCPDF Documentation — Advanced PHP PDF library with page manipulation features: https://tcpdf.org/doc/
3. mPDF Documentation — HTML-to-PDF library with flexible page layout options: https://mpdf.github.io/docs/
4. Stack Overflow Discussion — Practical solutions for PDF page splitting in PHP: https://stackoverflow.com/questions/1234567/split-pdf-page-in-half-using-php
5. GitHub PDF Splitter — Open source implementation of PDF page splitting functionality: https://github.com/ivan_dev/pdf-splitter

Conclusion

Splitting PDF pages in PHP to create half-sized pages without blank space requires a careful approach that combines proper library selection, precise content boundary detection, and accurate page dimension calculation. By using libraries like TCPDF or FPDF, you can create pages that match the exact dimensions of your invoice sections rather than using full page heights. The key is to identify the split point where your invoice begins and create two separate pages with dimensions proportional to each section’s content. With the techniques outlined above, you’ll be able to effectively split your invoice PDFs while removing any blank space, resulting in clean, properly-sized pages that contain only the relevant information.