(PECL imagick 2.0.0)
ImagickDraw::setStrokeAlpha — Specifies the opacity of stroked object outlines
$opacity
   )This function is currently not documented; only its argument list is available.
Specifies the opacity of stroked object outlines.
opacityopacity
No value is returned.
Example #1 ImagickDraw::setStrokeAlpha()
<?php
function setStrokeAlpha($strokeColor, $fillColor, $backgroundColor) {
    $draw = new \ImagickDraw();
    $draw->setStrokeColor($strokeColor);
    $draw->setFillColor($fillColor);
    $draw->setStrokeWidth(4);
    $draw->line(100, 100, 400, 145);
    $draw->rectangle(100, 200, 225, 350);
    $draw->setStrokeOpacity(0.1);
    $draw->line(100, 120, 400, 165);
    $draw->rectangle(275, 200, 400, 350);
    $image = new \Imagick();
    $image->newImage(500, 400, $backgroundColor);
    $image->setImageFormat("png");
    $image->drawImage($draw);
    header("Content-Type: image/png");
    echo $image->getImageBlob();
}
?>