Draw Lines in PDF document using FPDF

Line( x1, y1, x2, y2 );

<?php  
require('fpdf.php');  

$pdf = new FPDF();  
$pdf->AddPage();  

$pdf -> Line(20, 20, 150, 200);  

$pdf->Output();  
?>

Draw a cross X using full length of page

<?php  
require('fpdf.php');  

$pdf = new FPDF();  
$pdf->AddPage();  

$width = $pdf->GetPageWidth(); // Width of Current Page  
$height = $pdf->GetPageHeight(); // Height of Current Page  

$pdf->Line(0, 0, $width, $height); // Line one Cross  
$pdf->Line($width, 0, 0, $height); // Line two Cross  

$pdf->Output();  
?>

Draw border at a gap of 2 across the page

<?php  
require('fpdf.php');  

$pdf = new FPDF();  
$pdf->AddPage();  

$width = $pdf->GetPageWidth(); // Width of Current Page  
$height = $pdf->GetPageHeight(); // Height of Current Page  
$gap = 2; // Gap between line and border, change this value  

$pdf->Line($gap, $gap, $width - $gap, $gap); // Horizontal line at top  
$pdf->Line($gap, $height - $gap, $width - $gap, $height - $gap); // Horizontal line at bottom  
$pdf->Line($gap, $gap, $gap, $height - $gap); // Vertical line at left  
$pdf->Line($width - $gap, $gap, $width - $gap, $height - $gap); // Vertical line at right  

$pdf->Output();  
?>

Draw horizontal lines at a gap of 10 throughout the page

<?php  
require('fpdf.php');  

$pdf = new FPDF();  
$pdf->AddPage();  

$width = $pdf->GetPageWidth(); // Width of Current Page  
$height = $pdf->GetPageHeight(); // Height of Current Page  

$i = 0;  

for($i = 0; $i <= $height; $i += 10) {  
    $pdf -> Line(0, $i, $pdf -> w, $i);  
}  

$pdf->Output();  
?>

Draw patterns of square boxes with reducing dimension across the page

<?php  
require('fpdf.php');  

$pdf = new FPDF();  
$pdf->AddPage();  

$width = $pdf->GetPageWidth(); // Width of Current Page  
$height = $pdf->GetPageHeight(); // Height of Current Page  
$gap = 2; // Gap between line and border  

for ($gap = 2; $gap <= $width / 2; $gap += 2) {  

    $pdf->Line($gap, $gap, $width - $gap, $gap); // Horizontal line at top  
    $pdf->Line($gap, $height - $gap, $width - $gap, $height - $gap); // Horizontal line at bottom  
    $pdf->Line($gap, $gap, $gap, $height - $gap); // Vertical line at left  
    $pdf->Line($width - $gap, $gap, $width - $gap, $height - $gap); // Vertical line at right  
}  

$pdf->Output();  
?>

SetLineWidth(float width)

$pdf->SetLineWidth(0.8);

SetDrawColor(R,G,B) to change line color

$pdf->SetDrawColor(10, 10, 10);

<?php  
require('fpdf.php');  

$pdf = new FPDF();  
$pdf->AddPage();  

$width = $pdf->GetPageWidth(); // Width of Current Page  
$height = $pdf->GetPageHeight(); // Height of Current Page  
$gap = 2; // Gap between line and border  

$pdf->SetLineWidth(0.8);  
$pdf->SetDrawColor(10, 10, 10);  

for ($gap = 2; $gap <= $width / 2; $gap += 5) {  
    $pdf->SetDrawColor(10 + (3 * $gap), 10 + $gap, 10 + $gap);  

    $pdf->Line($gap, $gap, $width - $gap, $gap); // Horizontal line at top  

    $pdf->Line($gap, $height - $gap, $width - $gap, $height - $gap); // Horizontal line at bottom  

    $pdf->Line($gap, $gap, $gap, $height - $gap); // Vertical line at left  

    $pdf->Line($width - $gap, $gap, $width - $gap, $height - $gap); // Vertical line at right  
}  

$pdf->Output();  
?>