Imagick::distrortImage control points array function

getControlPointsForPerspectiveDistortion.php

/**
 * Returns an array of control points for use with Imagick::distortImage
 *
 * Offset floats describe the proportions between 0.0 and 1.0 to move the
 * given anchor point toward the opposite corner of the image. For example,
 * an image of size 100x100. $topLeftOffsetX = .2, $topLeftOffsetY = .5
 * will move the top left corner down and right from (0,0) to (20,50).
 * $bottomRightOffsetX = .2, $bottomRightOffsetY will move the bottom right
 * corner up and left from (100,100) to (80,50).
 *
 * Providing 1.0 for all values will flip the image horizontally and
 * vertically.
 *
 * @param int $width Width of the image to distort
 * @param int $height Height of the image to distort
 * @param float $topLeftOffsetX
 * @param float $topLeftOffsetY
 * @param float $topRightOffsetX
 * @param float $topRightOffsetY
 * @param float $bottomRightOffsetX
 * @param float $bottomRightOffsetY
 * @param float $bottomLeftOffsetX
 * @param float $bottomLeftOffsetY
 * @return float[] Array of control points for Imagick::distortImage
 */
function getControlPointsForPerspectiveDistortion(
    $width,
    $height,
    $topLeftOffsetX = 0.0,
    $topLeftOffsetY = 0.0,
    $topRightOffsetX = 0.0,
    $topRightOffsetY = 0.0,
    $bottomRightOffsetX = 0.0,
    $bottomRightOffsetY = 0.0,
    $bottomLeftOffsetX = 0.0,
    $bottomLeftOffsetY = 0.0
) {
    return array(
        // Top left source
        0, 0, 
        // Top left destination
        $width * $topLeftOffsetX, $height * $topLeftOffsetY,
        // Top right source
        $width, 0,
        // Top right destination
        $width - ($width * $topRightOffsetX), $height * $topRightOffsetY,
        // Bottom right source
        $width, $height, 
        // Bottom right destination
        $width - $width * $bottomRightOffsetX, 
        // Bottomleft source
        $height - ($height * $bottomRightOffsetY),
        // Bottom left destination
        0, $height, $width * $bottomLeftOffsetX, $height - $height * $bottomLeftOffsetY
    );
}