PHP | ImagickPixelIterator getPreviousIteratorRow() Function

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The ImagickPixelIterator::getPreviousIteratorRow() function is an inbuilt function in PHP which is used to get the previous row as an array of pixel wands from the pixel iterator.

Syntax:

array ImagickPixelIterator::getPreviousIteratorRow( void )

Parameters: This function doesn’t accepts any parameters.

Return Value: This function returns an array value containing ImagickPixel objects.

Below programs illustrate the ImagickPixelIterator::getPreviousIteratorRow() function in PHP:

Program 1:

<?php 
  
// Create a new imagick object 
$imagick = new Imagick( 
'https://media.zambiatek.com/wp-content/uploads/zambiatek-13.png'); 
   
// Get the pixel iterator 
$pixelIterator = $imagick->getPixelIterator(); 
   
// Set the pixel iterator to 50 
$pixelIterator->setIteratorRow(50); 
  
// Move one step to previous row 
$pixelIterator->getPreviousIteratorRow(); 
   
// Get the current iterator row 
echo "Current row is " . $pixelIterator->getIteratorRow(); 
?> 

Output:

Current row is 49

Program 2:

<?php 
  
// Create a new imagick object 
$imagick = new Imagick(); 
  
// Create a image on imagick object 
$imagick->newImage(800, 250, 'black'); 
  
$imageIterator = $imagick->getPixelIterator(); 
  
$x = 0; 
  
// Set the iterator row to last row 
$imageIterator->setIteratorRow(249); 
  
while ($x < 250) { 
  
    // Get the previous row 
    $pixels = $imageIterator->getPreviousIteratorRow(); 
  
    foreach ($pixels as $pixel) { 
        if ($x % 4) { 
  
            // Set the color of pixel 
            $pixel->setColor('green'); 
  
        } else { 
  
            // Set the color of pixel 
            $pixel->setColor('red'); 
        } 
    } 
  
    // Sync the iterator 
    $imageIterator->syncIterator(); 
      
    $x++; 
} 
  
// Show the output 
$imagick->setImageFormat('png'); 
header("Content-Type: image/png"); 
echo $imagick->getImageBlob(); 
?> 