Question

im trying to complete this function, it seems to be working great except for 1 small problem – it seems to position the image too far to the left and then fills the rest of the space with black.

what i’m trying to do is get this function to resize the image to the specified $thumb_w, and if the height ends up being bigger than then $thumb_h after being resized, it just crops out the bottom.

heres my function code:

function resize_upload ($tmp, $thumb_w, $thumb_h, $img_name, $img_ext, $img_path)
{
    if ($img_ext == 'jpg' || $img_ext == 'jpeg' || $img_ext == 'png' || $img_ext == 'gif')
    {
        if ($img_ext == 'jpg' || $img_ext == 'jpeg')
            $source_img = imagecreatefromjpeg($tmp);
        else if ($img_ext=='png')
            $source_img = imagecreatefrompng($tmp);
        else 
            $source_img = imagecreatefromgif($tmp);

        $orig_w = imagesx($source_img);
        $orig_h = imagesy($source_img);

        $w_ratio = ($thumb_w / $orig_w);
        $h_ratio = ($thumb_h / $orig_h);

        if ($orig_w > $orig_h ) 
        {
            $crop_w = round($orig_w * $h_ratio);
            $crop_h = $thumb_h;
            $src_x = ceil( ( $orig_w - $thumb_w ) / 2 );
            $src_y = 0;
        } 
        elseif ($orig_w < $orig_h ) 
        {
            $crop_h = round($orig_h * $w_ratio);
            $crop_w = $thumb_w;
            $src_x = 0;
            $src_y = ceil( ( $orig_h - $thumb_h ) / 2 );
        } 
        else 
        {
            $crop_w = $thumb_w;
            $crop_h = $thumb_h;
            $src_x = 0;
            $src_y = 0;
        }

        $thumb_img = imagecreatetruecolor($thumb_w,$thumb_h);

        imagecopyresampled($thumb_img, $source_img, 0 , 0 , $src_x, $src_y, $crop_w, $crop_h, $orig_w, $orig_h);

        imagejpeg($thumb_img, $img_path.'/'.$img_name.'.'.$img_ext, 100);

        imagedestroy($thumb_img);
        imagedestroy($source_img);
    }
}

heres how i call the function:

resize_upload ($_FILES['image_main']['tmp_name'], 556, 346, $img_name, $img_ext, '../wp-content/themes/my-theme/images/projects');

heres what the image ends up looking like after the function does its thing:

see the black on the right-hand side? its probably some math problem i can’t figure out. any help would be greatly appreciated.

Answer 1

Using the same variables from your post $thumb_w = 556, $thumb_h = 346, let’s assume that the image that was sent in was the exact same dimensions, and thus wouldn’t need resized (556×346).

    $orig_w = 556;
    $orig_h = 346;

    $w_ratio = 1;
    $h_ratio = 1;

    if (556 > 346) //true
    {
        $crop_w = round(556 * 1); // 556
        $crop_h = 346;
        $src_x = ceil( ( 556 - 346 ) / 2 ); // ceil( 210 / 2 ) == 105;
        $src_y = 0;
    } 

    ...

    $thumb_img = imagecreatetruecolor(556, 346);

    imagecopyresampled($thumb_img, $source_img, 0, 0, 105, 0, 556, 346, 556, 346);

So your code is starting at x = 105 of your source image, and attempting to go 556 pixels to the right of that, but only 451 pixels exist past that point. So if I had sent in a 556×346 image, it would copy the width of pixels 105 through 556 for the horizontal part of the image, and then 0 through 346 for the vertical. Thus, the entire vertical piece of the image shows up, but not all of the width.

I’m sure if we did these same calculations with an image which had a greater height than width, we’d have the same problem with it having black space at the bottom of the image instead.

Tip: When writing formulas and other things that require a lot of calculations, go through them with the simplest numbers first. If those don’t work, you obviously did something wrong.