Add apply alpha layer mask

[GoodLittleDev]

add this code to: ImageWorkshopLayer.php
too allow you to apply layer mask.
to use $layer_you_wish_to_apply_mask->applyalphamask($mask_layer);

/**
* Apply alpha layer mask.
* can be slower so best for images you don't need to remake for every user.
* @param layer $mask
*
* @author email [email protected]
*
*/

public function applyalphamask($mask){
    $layerWidth = $this->width;
    $layerHeight = $this->height;

    $masktemp = clone $mask;

    $masktemp->resizeInPixel($layerWidth, $layerHeight); // make $mask and $layer the same size.
    $masktemp->applyFilter(IMG_FILTER_GRAYSCALE); //converts to greyscale if not greyscale;
    $masktemp->applyFilter(IMG_FILTER_NEGATE); 

    $layerImg= $this->getImage();
    $maskImg = $masktemp->getImage();

    $imgtemp = imageCreateTrueColor($layerWidth,$layerHeight);

    imagealphablending($imgtemp, false);
    imagesavealpha($imgtemp, true);


    for ($h=0; $h<$layerHeight; $h++){
        for ($w=0; $w<$layerWidth; $w++){
            $Lrgb = imagecolorat($layerImg, $w, $h);
            $Lcolors = imagecolorsforindex($layerImg, $Lrgb);

            $Mrgb = imagecolorat($maskImg, $w, $h);
            $Mcolors = imagecolorsforindex($maskImg, $Mrgb);

            $alpha = $Mcolors["red"]/255*127;
            //$alpha = (int)( $alpha);

            imagesetpixel($imgtemp,$w,$h,imagecolorallocatealpha($imgtemp,$Lcolors["red"],$Lcolors["green"],$Lcolors["blue"],$alpha));
    }}

    imagepng($imgtemp, realpath(dirname(__FILE__))."\imgtem.png");

    //imagecopyresampled($imgtemp, $this->image, 0, 0, 0, 0, $this->width, $this->height, -$this->width, $this->height);     
    $this->image = $imgtemp;
}