如何在Imagick中设置图像像素颜色？

Question

i am using Imagick for image processing. I am unable to find any native function to set a particular pixel color while there is one to get one. I mean,

$image->getimagepixelcolor($i, $j);

will return an object to get the color of pixel at ($i, $j) but there doesn't seems to be a method to set color. Something like this,

$image->setimagepixelcolor($i, $j, "#FFFFFF");

Answer 1

There would be no setImagePixelColor method on the Imagick class. I can't speak of why there isn't one, but one can achieve the same effects by invoking the ImagickPixelIterator, or ImagickDraw class.

Iterator Example:

The proper way would be to iterator over the pixels in an image, alter a pixels color, then sync the data back to the image.

$image = new Imagick('source.png');

// Grab iterator
$iterator = $image->getPixelIterator();
// Seek to row at Y
$iterator->setIteratorRow($j);
// Get pixel in row
$row = $iterator->getCurrentIteratorRow();
// Seek to pixel at X
$pixel = $row[$i];
// Set Color
$pixel->setColor('#FFFFFF');
// Sync data back to image
$iterator->syncIterator();

$image->writeImage('out.png');

Draw Example:

The other option would be to draw the new pixel on top of the existing image.

$image = new Imagick('source.png');
$draw  = new ImagickDraw();
$color = new ImagickPixel('#FFFFFF');

// Set fill color
$draw->setFillColor($color);
// Draw a point at X,Y
$draw->point($i,$j);
// Apply the drawing on top of the image
$image->drawImage($draw);

$image->writeImage('dest.png');

Of course with Object's in PHP, you can simple extend the core Imagick object, and create your own setImagePixelColor method

class MyImagick extends Imagick 
{
   /**
    * Alter image by defining the color of a single pixel
    *
    * @param integer $x
    * @param integer $y
    * @param string $color
    */
   public function setImagePixelColor($x,$y, $color) 
   {
      //... Apply one of the methods here
      $draw  = new ImagickDraw();
      $draw->setFillColor(new ImagickPixel($color));
      $draw->point($x,$y);
      $this->drawImage($draw);
   }
}