How to generate PDF files using PHP

In the application of modern Internet technology, PDF files are widely used as a cross-platform standard document format. As one of the most popular server-side programming languages, PHP is also very practical for processing PDF files. This article will introduce how to use PHP to generate PDF files.

1. Install related extensions

Generating PDF files requires the use of a PDF library, which can be achieved by installing PDF-related extensions. Commonly used PDF extensions include the following:

1. TCPDF extension

TCPDF is a PHP class library used to generate PDF files. It is completely written in PHP language, so you can easily generate PDF files in PHP environment.

You can use Composer to install the TCPDF extension. Add the following code to your project:

{
    "require": {
        "tecnickcom/tcpdf": "^6.2"
    }
}

2. mPDF extension

mPDF is a PHP based on TDCPDF Class library, which can not only generate PDF files, but also generate files in HTML, XHTML and CSS formats.

You can use Composer to install the mPDF extension and add the following code to your project:

{
    "require": {
        "mpdf/mpdf": "*"
    }
}

2. Generate a simple PDF file

Before we start generating PDF files , let’s first take a look at the steps required to generate a simple PDF file:

1. Create PDF instance
2. Define PDF page
3. Output PDF content
4. Save PDF file

Next we will follow these four steps to generate a simple PDF file.

1. Create PDF instance

First, we need to create a PDF instance to define parameters such as page size and margins. The following is an example of creating a TCPDF instance:

require_once('tcpdf/tcpdf.php');

$pdf = new TCPDF(PDF_PAGE_ORIENTATION, PDF_UNIT, PDF_PAGE_FORMAT, true, 'UTF-8', false);

Among them, PDF_PAGE_ORIENTATION is used to define the page orientation. PDF_UNIT is used to define page units. PDF_PAGE_FORMAT is used to define the page size. true means use unicode fonts. 'UTF-8' is used to define the character encoding. false means not to use anti-aliasing.

2. Define PDF page

Defining PDF page means setting the size, margin, font and other styles of PDF page. The following is an example of defining a TCPDF page:

// 设置页面信息
$pdf->SetCreator(PDF_CREATOR);
$pdf->SetAuthor('Author');
$pdf->SetTitle('Title');
$pdf->SetSubject('Subject');
$pdf->SetKeywords('TCPDF, PDF, example');

// 设置页面边距和大小
$pdf->SetMargins(PDF_MARGIN_LEFT, PDF_MARGIN_TOP, PDF_MARGIN_RIGHT);
$pdf->SetHeaderMargin(PDF_MARGIN_HEADER);
$pdf->SetFooterMargin(PDF_MARGIN_FOOTER);
$pdf->SetAutoPageBreak(TRUE, PDF_MARGIN_BOTTOM);
$pdf->setImageScale(PDF_IMAGE_SCALE_RATIO);

// 设置默认字体
$pdf->SetFont('cid0cs', '', 12);

Among them, SetMargins, SetHeaderMargin, SetFooterMargin and SetAutoPageBreak are used to set PDF page margins, headers, footers and paging. setImageScale is used to set the proportion of PDF images. SetFont is used to set the font and size of PDF text.

3. Output PDF content

Outputting PDF content refers to converting HTML text into PDF documents. In TCPDF, we can use the writeHTML method to achieve this. The following is an example of outputting TCPDF content:

$pdf->AddPage();

$html = '<h1>My PDF</h1>';
$html .= '<p>This is my first PDF generated with TCPDF.</p>';

$pdf->writeHTML($html, true, false, true, false, '');

Among them, AddPage is used to add a new PDF page. writeHTML is used to output HTML text into a PDF document.

4. Save the PDF file

The final step is to save the PDF file to disk. In TCPDF, we can use the Output method to achieve this. The following is an example of saving a TCPDF file:

$pdf->Output('my_pdf.pdf', 'D');

where, my_pdf.pdf represents the name of the PDF file. 'D' means the PDF file is output directly to the user's browser. You can also use other parameters, for example: 'I' means to output the PDF file to the browser, 'F' means to save the PDF file to disk.

3. Use mPDF to generate PDF files

In the previous article, we introduced how to use TCPDF to generate PDF files. If you want to use mPDF to generate PDF files, then here is an example of simply using mPDF to generate PDF files:

require_once(__DIR__.'/vendor/autoload.php');

$mpdf = new MpdfMpdf();

$mpdf->WriteHTML('<h1>Hello world</h1>');

$mpdf->Output();

Among them, __DIR__.'/vendor/autoload.php' is the mPDF library that is automatically loaded through Composer. WriteHTML is used to output HTML text into a PDF document. Output is used to output PDF files to the browser or disk.

4. Conclusion

PHP can use TCPDF or mPDF class library to generate PDF files. You need to install the relevant extensions first, and then follow the steps below to generate PDF files:

1. Create PDF instance
2. Define PDF page
3. Output PDF content
4. Save PDF files

If you need to convert the HTML page into a PDF document, first replace the HTML page with the writeHTML() function of TCPDF with the WriteHTML function of mPDF. Generating PDF files using PHP is very simple and can be used in many scenarios, such as converting web content into PDF documents for users to download and share.

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