Best practices and common problem solving for image embedding in Laravel Dompdf PDF generation

This article aims to solve the problem that images cannot be displayed correctly when generating PDF in Laravel Dompdf. The traditional use of `public_path()` to reference the image path often fails in the Dompdf environment. This tutorial will introduce in detail how to Base64 encode the image content and embed it directly into HTML ` ` tag to ensure that the image is displayed stably and reliably in the generated PDF file. This method works in Laravel 8 and above and is an effective strategy for handling such image embedding challenges.

When using Laravel's Dompdf service provider to generate PDF files, developers often encounter the problem that images cannot be displayed correctly, even if auxiliary functions such as public_path() are used to specify the image path. This is mainly because when Dompdf renders HTML to PDF, its internal rendering engine parses the file system path differently from the browser's direct access to the URL. Dompdf cannot obtain image resources directly through the public path of the server (such as the URL corresponding to public/image.png). The most reliable solution is to embed the image data directly into the HTML rather than relying on external links.

Core solution: Base64 encoded images

Base64 encoding the image content and then embedding the encoded string directly into the src attribute of the HTML tag is a versatile and highly reliable method. This method includes image data directly in HTML as text content, so that the PDF renderer does not need to make additional network requests or file system searches, ensuring that images can be displayed stably.

Step 1: Get the image content in the controller and encode it in Base64

Before passing the data to the Blade view, you need to read the image file in the controller, encode its contents into a Base64 string, and get the MIME type of the image.

Let's say your image is located at public/images/logo.png.

 <?php namespace App\Http\Controllers;

use Illuminate\Http\Request;
use App\Models\Order; // Assume your Order model use App\Models\UserData; // Assume your UserData model use PDF; // Make sure the Dompdf facade class InvoiceController extends Controller is introduced
{
    public function invoicepdf($productid, $orderId)
    {
        // Original business logic for obtaining order, product and merchant details $orderHistory = Order::where(&#39;order_id&#39;, $orderId)->orderBy('id', 'DESC')-&gt;first();
        $orderProductDetails = json_decode($orderHistory-&gt;product_details, true);
        $productDetails = [];
        $marchantdetails = null;

        foreach ($orderProductDetails as $orderdata) {
            foreach ($orderdata as $orderDetail) {
                if ($orderDetail['product_id'] == $productid) {
                    $productDetails = $orderDetail;
                    $marchantdetails = UserData::where('user_id', $orderDetail['marchent_id'])-&gt;first();
                    break 2; // Break out of the two-level loop after finding the match}
            }
        }

        // --- Image processing begins ---
        $imagePath = public_path('images/logo.png'); // Specify your image path $imageData = null;
        $imageMime = null;

        if (file_exists($imagePath)) {
            // Read the image content and perform Base64 encoding $imageData = base64_encode(file_get_contents($imagePath));
            // Get the MIME type of the image, such as 'image/png', 'image/jpeg'
            $imageMime = mime_content_type($imagePath);
        }
        // --- Image processing ends ---

        // Pass the encoded image data and MIME type to the view $pdf = PDF::loadView('front_end.invoice', compact('orderHistory', 'productDetails', 'marchantdetails', 'imageData', 'imageMime'))
                  -&gt;setOptions(['defaultFont' =&gt; 'sans-serif']); // Optional: Set the default font to support Chinese, etc. // Download PDF file return $pdf-&gt;download('invoice_' . $orderId . '.pdf');
    }
}

Code description:

• public_path('images/logo.png'): used to obtain the absolute path of the image in the file system. Please adjust according to your actual picture location.
• file_exists($imagePath): Check whether the image file exists to avoid errors due to file non-existence.
• file_get_contents($imagePath): Read the binary content of the image file.
• base64_encode(): Encode binary content into Base64 string.
• mime_content_type($imagePath): Dynamically obtain the MIME type of the image, which is very important for constructing data: URI.

Step 2: Embed the Base64 encoded image in the Blade template

In your Blade view file (front_end/invoice.blade.php), embed the Base64-encoded image directly into the tag using the data: URI scheme.

 


    <meta charset="utf-8">
    <title>Invoice</title>
    <style>
        /* You can add some basic styles here*/
        body {
            font-family: &#39;sans-serif&#39;; /* Make sure the font is consistent with Dompdf settings*/
        }
        .center-image {
            text-align: center;
            margin-bottom: 20px;
        }
    </style>


    <div class="center-image">
        @if ($imageData &amp;&amp; $imageMime)
            <!-- Image data encoded using Base64 -->
            <img  src="data:%7B%7B%20%24imageMime%20%7D%7D;base64,%7B%7B%20%24imageData%20%7D%7D"   style="max-width:90%" alt="Best practices and common problem solving for image embedding in Laravel Dompdf PDF generation" >
        @else
            <!-- Placeholder or prompt when the image does not exist -->
            <p>Image not found or could not be loaded. </p>
        @endif
    </div>

    <h1>Invoice details</h1>
    <p>Order number: {{ $orderHistory-&gt;order_id }}</p>
    <p>Product name: {{ $productDetails['product_name'] ?? 'N/A' }}</p>
    <p>Merchant: {{ $marchantdetails-&gt;name ?? 'N/A' }}</p>

    <p>ut aliquip ex ea commodoconsequat. Duis aute irure dolor in reprehenderit in voluptate velit esse
    cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidata.</p>

    <!-- More invoice content-->

Code description:

• src="data:{{ $imageMime }};base64,{{ $imageData }}": This is the key part. data: URI allows embedding file content directly in HTML.
  • {{ $imageMime }}: The image MIME type passed by the controller (eg image/png).
  • base64,: indicates that the following data is Base64 encoded.
  • {{ $imageData }}: Base64 encoded image string passed by the controller.
• The size and style of the image can be controlled through the style attribute of the tag.

Things to note

1. Image size and performance: Base64 encoding increases image file size by approximately 33%. This is acceptable for small icons or logos. But if you need to embed a large number of or very large images, this may significantly increase the size of the PDF file, extend the generation time, and consume more server memory. In this case, it may be necessary to re-evaluate the plan or optimize the image.
2. MIME type accuracy: Make sure the MIME type in the data: URI (eg image/png, image/jpeg) matches the actual image type. Wrong MIME type may cause the image not to be displayed. The correct MIME type can be obtained dynamically using the mime_content_type() function.
3. Font issues: Dompdf may require additional font configuration when handling non-Latin characters such as Chinese. If the PDF contains Chinese, please ensure that a Chinese-supporting font is set in the Dompdf configuration (such as setOptions(['defaultFont' => 'sans-serif']), and ensure that the font is installed on the server or a custom font is registered in Dompdf).
4. Image path: When reading images in the controller, make sure the image path is correct and the PHP process has permission to read the file. public_path() is a convenient way to get the path of a file in a public directory.

Summarize

By Base64 encoding the image content and embedding it directly into the tag of HTML, you can effectively solve the problem that Laravel Dompdf cannot display images when generating PDF. This method ensures the self-contained nature of image data and avoids various compatibility issues that the Dompdf rendering engine may encounter when parsing external image paths. Although you need to be aware of the performance overhead that large images may bring, this is the most reliable and recommended solution for most PDF documents that contain logos or small icons.

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