How to Generate a PDF With PHP

As mentioned earlier, there are different settings for the measurement units on the PDF pages within FPDF. You can control them by sending parameters to the constructor when you instantiate a new copy of the class. Previously, you saw the $pdf = new FPDF( ); statement of instantiation, which creates an object with the default attributes. You can send the following parameters into the constructor:

Here is a constructor call that defines portrait, inches, and letter layout:

$pdf = new FPDF('P', 'in', 'Letter' );

$pdf = new FPDF('L', 'in', array(4,5));

Let’s take a look at object inheritance, or extension, in action. Naturally, there is often a need for headers and footers on a multipage PDF document. FPDF has empty header and footer methods, and they are called automatically each time the AddPage method is called. Without extending the class and adding content to our own methods of the same names, however, nothing is visually apparent. So, let’s extend the class and add custom page header and footer methods to the child class. Here is the code:

require("../../fpdf/fpdf.php");



class myPDF extends FPDF {



	public $title = "FPDF Sample Page Header";



	//Page header method

	function Header() {



 	$this->SetFont('Times','',12);

 	$w = $this->GetStringWidth($this->title)+150;

 	$this->SetDrawColor(0,0,180);

 	$this->SetFillColor(170,169,148);

 	$this->SetTextColor(0,0,255);

 	$this->SetLineWidth(1);

 	$this->Cell($w,9,$this->title,1,1,'C',1);

 	$this->Ln(10);



	}



	//Page footer method

	function Footer() 	{

 	//Position at 1.5 cm from bottom

 	$this->SetY(-15);

 	$this->SetFont('Arial','I',8);

 	$this->Cell(0,10,'page footer -> Page '

 	.$this->PageNo().'/{nb}',0,0,'C');

	}



}



$pdf = new myPDF('P', 'mm', 'Letter');

$pdf->AliasNbPages();

$pdf->AddPage();

$pdf->SetFont('Times','',24);

$pdf->Cell(0,0,'text at the top of the page',0,0,'L');

$pdf->ln(225);

$pdf->Cell(0,0,'text near page bottom',0,0,'C');

$pdf->AddPage();

$pdf->SetFont('Arial','B',15);

$pdf->Cell(0,0,'Top of page 2 after page header',0,1,'C');

$pdf->Output();

There are a number of other methods being called from within the extended header and footer methods. Some of this is included here to show you that the entire class is inherited and not just the header and footer methods. Also, some of the methods are used to show the difference between the header and footer areas distinctly. The full listing of methods and their uses can be found on the product web page under the “Manual” link. The image shown in Figure 8.5 is the result of the above code being executed within the browser. It is a picture of the bottom of one page (to show the footer) and the top of the next page (to show the header).

Figure 8.5. Generated PDF with page headers and footers

You can also add image and link content to PDF files with the FPDF library. These links can be anchors within the PDF file itself or full URL resources on the Web. First, we will look at inserting images into the PDF file, then we will look at making links from either images or text.

To add an image to the document, simply use the image method. In the following code, we will use the image method within the header method to add a PHP logo to the page header and remove the background fill color option from the cell method call so that we can see the image. The image parameters are the image filename, the x and y coordinates of the image, and the width and height of the image:

function Header() {



	$this->SetFont('Times','',12);

	$w = $this->GetStringWidth($this->title)+150;

	$this->SetTextColor(0,0,255);

	$this->SetLineWidth(1);

	$this->Image('phplogo.jpg',10,10.5,15,8.5);

	$this->Cell($w,9,$this->title,1,1,'C');

	$this->Ln(10);



}

The PDF document now looks like the image shown in Figure 8.6.

Figure 8.6. Generated PDF with image included in the page header

Now, to make this image link to the PHP home page, simply add the URL to the last parameter of the image method, skipping the type parameter with a comma.

The new linking method call now looks like this:

$php_url = "http://www.php.net" ;

$this->Image('phplogo.jpg',10,10.5,15,8.5,"",$php_url);

The image is now a clickable link image, as shown by the hover text in Figure 8.7.

Figure 8.7. Inserted image with active URL link

The other kind of link that we can add to the PDF document is a link to another location within the document. This is the concept of a table of contents or an index. Creating an internal link is done in two parts. First, you define the origin for the link (the link itself), then you set the anchor (the destination that the link will take you to when you click it).

To set the origin of a link, use the AddLink() method. This method returns a handle for use when creating the destination portion of the link with the SetLink() method, which takes the origin’s link handle as its parameter so that it can perform the connection between the two items. Here is some sample code that performs the creation of both the origin and the destination parts; notice the use of the FPDF write method, which is another way to send text to the document (as opposed to using the cell method):

require("../../fpdf/fpdf.php");



$pdf = new FPDF();



//First page

$pdf->AddPage();

$pdf->SetFont('Times','',14);



$pdf->write(5,'For a link to page 2 - Click ');

$pdf->SetFont('','U');

$pdf->SetTextColor(0,0,255);

$link_to_pg2 = $pdf->AddLink();

$pdf->write(5,'here',$link_to_pg2);

$pdf->SetFont('');



//Second page

$pdf->AddPage();

$pdf->SetLink($link_to_pg2);

$pdf->Image('phplogo.jpg',10,10,30,0,'','http://www.php.net');

$pdf->ln(20);

$pdf->SetTextColor(1);

$pdf->Cell(0,5,'This is a link and a clickable image', 0, 1, 'L');

$pdf->SetFont('','U');

$pdf->SetTextColor(0,0,255);

$pdf->Write(5,'www.oreilly.com','http://www.oreilly.com');

$pdf->Output();

The browser outputs for both the link and the destination page for this code are shown in Figures 8.8 and 8.9.

Figure 8.8. PDF document generated with an internal link

Figure 8.9. Anchor page of PDF sample code with additional links

The next feature that we’ll look at is making a watermark appear on the PDF document. This can be a nice addition to generated reports or sales brochures that you may want to create within a PHP application. Here is the code to create the watermark:

require("../../fpdf/fpdf.php");



$pdf = new FPDF( );

$pdf->AddPage();

$pdf->SetFont('Arial','B',16);

$pdf->SetXY(26,100);

$pdf->image('php_watermark.jpg');

$pdf->SetY(35);

$text = "This is sample text to show the watermark underneath it.";

for($i = 0; $i < 35; $i++) { $pdf->Cell(0,5,$text,0,1); }

$pdf->Output();

All that is really going on here is that we are moving the write cursor around the page with the SetXY and SetY methods, and we have an image that is set to a semitransparent shading level. There is really no difference here from setting an image on the page, except that we are overwriting the image with additional text. If this had not been a semitransparent image, the text and the image would be garbled together and it would look like a mess.

Make sure you add the image to the document first in the case of a watermark, as the last items sent to the document will overwrite anything previously sent. In Figure 8.10, if the text were sent out first, followed by the image, the image would overlay the text.

Figure 8.10. PDF with generated watermark

Now we want to really make FPDF earn its keep. Up to this point, we have only been sending static information to the PDFs being created. Let’s look at how to integrate a PDF document with database information drawn out by a query request. We will display that information in a nicely formatted table on the PDF itself, thus making the PDF dynamic in its content. The following code listing is a little long, but it is well commented and the highlights are discussed in the subsequent paragraphs:

require("../../fpdf/fpdf.php");



class PDF extends FPDF {



	function BuildTable($header,$data) {

 	//Colors, line width and bold font

 	$this->SetFillColor(255,0,0);

 	$this->SetTextColor(255);

 	$this->SetDrawColor(128,0,0);

 	$this->SetLineWidth(.3);

 	$this->SetFont('','B');

 	//Header

 	// make an array for the column widths

 	$w=array(85,40,15);

 	// send the headers to the PDF document

 	for($i=0;$i<count($header);$i++)

 	$this->Cell($w[$i],7,$header[$i],1,0,'C',1);

 	$this->Ln();

 	//Color and font restoration

 	$this->SetFillColor(175);

 	$this->SetTextColor(0);

 	$this->SetFont('');



 	//now spool out the data from the $data array

 	$fill=true; // used to alternate row color backgrounds

 	foreach($data as $row)

 	{

 	$this->Cell($w[0],6,$row[0],'LR',0,'L',$fill);

 	// set colors to show a URL style link

 	$this->SetTextColor(0,0,255);

 	$this->SetFont('', 'U');

 	$this->Cell($w[1],6,$row[1],'LR',0,'L',$fill, 'http://www.oreilly.com');

 	// restore normal color settings

 	$this->SetTextColor(0);

 	$this->SetFont('');

 	$this->Cell($w[2],6,$row[2],'LR',0,'C',$fill);



 	$this->Ln();

 	// flips from true to false and vise versa

 	$fill =! $fill;

 	}

 	$this->Cell(array_sum($w),0,'','T');

	}

}



//connect to database

$connection = mysql_connect("localhost","user", "password");

$db = "library";

mysql_select_db($db, $connection)

	or die( "Could not open $db database");





$sql = 'SELECT * FROM books ORDER BY pub_year';

$result = mysql_query($sql, $connection)

	or die( "Could not execute sql: $sql");



// build the data array from the database records.

While($row = mysql_fetch_array($result)) {

	$data[] = array($row['title'], $row['ISBN'], $row['pub_year'] );

}



// start and build the PDF document

$pdf = new PDF();



//Column titles

$header=array('Book Title','ISBN','Year');



$pdf->SetFont('Arial','',14);

$pdf->AddPage();

// call the table creation method

$pdf->BuildTable($header,$data);

$pdf->Output();

In this code, we use the database connection and build two arrays to send to the BuildTable() custom method of this extended class. Inside the BuildTable() method, we set colors and font attributes for the table header, then send out the headers based on the first array passed in. An array called $w (for width) sets the column widths and is used in the calls to the cell() methods.

After the table header is sent out, we use the $data array that contains the database information and walk through that array with a foreach loop. Notice here that the cell() method uses LR for its border parameter. This refers to borders on the left and right of the cell in question, thus effectively adding the sides to the table rows. We also add a URL link to the second column just to show that it can be done in connection with the table row construction. Finally, we use a $fill variable to flip back and forth so that the background color will alternate as the table is constructed row by row.

The final call to the cell() method in this BuildTable() method draws the bottom of the table and closes off the columns.

The result of executing this code in a browser is shown in Figure 8.11.

Figure 8.11. Table data taken from MySQL placed in a dynamic PDF