php - imagecopyresampled

Question

I'm trying to use jcrop to allow users to create a thumbnail of their image, it will be 190x190 pixels .

jcrop seems to be working and sending me the correct coordinates. However, imagecopyresampled seems to be acting very unpredictably and not giving me what I expect. Here is my code:

$destWidth = $destHeight = 190;
$jpeg_quality = 90;
$path = Yii::app()->basePath."/../images/user/";
$src = $path.$model->image;

$img_src = imagecreatefromjpeg($src);
$img_dest = ImageCreateTrueColor( $destWidth, $destHeight );

imagecopyresampled(
$img_dest, //destination image
$img_src, //source image
0, //top left coordinate of the destination image in x direction
0, //top left coordinate of the destination image in y direction
$_POST['x'], //top left coordinate in x direction of source image that I want copying to start at
$_POST['y'], //top left coordinate in y direction of source image that I want copying to start at
$destWidth, //190, thumbnail width
$destHeight, //190, thumbnail height
$_POST['w'], //how wide the rectangle from the source image we want thumbnailed is
$_POST['h'] //how high the rectangle from the source image we want thumbnailed is
);

imagejpeg($img_dest,$path."thumbs/test.jpg",$jpeg_quality);

I'm seriously at a loss, I've checked that the four $_POST variables are all coming in correctly, but for some reason I can't get a proper thumbnail. All I can tell for sure is that the thumbnail is usually zoomed in too much and that the top left corner I want it to start from isn't being used.

Answer 1

This is my final source code. I found out that my CSS was conflicting with my code since it allowed a max-height of 550px and a max-width of 700px. This caused images larger to have incorrect widths and/or heights. So in these cases I had to add a multiplier based on the aspect ratio of the image, and how the CSS would have resized it.

        $destWidth = $destHeight = 190;
        $jpeg_quality = 90;

        $path = Yii::app()->basePath."/../images/user/";
        $src = $path.$model->image;
        $img_src = imagecreatefromjpeg($src);
        $img_dest = ImageCreateTrueColor( $destWidth, $destHeight );

        //
        // IMPORTANT!! 
        // If you change the max-width or max-height in the css, you MUST change them here too!!
        //
        $maxWidth = 700;
        $maxHeight = 550;

        $srcWidth = imagesx($img_src);
        $srcHeight = imagesy($img_src);
        $srcRatio = $srcWidth/$srcHeight;
        $mult = 1;

        //if the image is wider than the max allowed width AND has a wider aspect ratio than a max height + max width image
        if ($srcWidth > $maxWidth && $srcRatio > $maxWidth/$maxHeight) {
            $mult = $srcWidth/$maxWidth;
        //else if the image is taller than the max height
        } else if ($srcHeight > $maxHeight) {
            $mult = $srcHeight/$maxHeight;
        }

        imagecopyresampled(
            $img_dest, //destination image
            $img_src, //source image
            0, //top left coordinate of the destination image in x direction
            0, //top left coordinate of the destination image in y direction
            $_POST['x']*$mult, //top left coordinate in x direction of source image that I want copying to start at
            $_POST['y']*$mult, //top left coordinate in y direction of source image that I want copying to start at
            $destWidth, //190, thumbnail width
            $destHeight, //190, thumbnail height
            $_POST['w']*$mult, //how wide the rectangle from the source image we want thumbnailed is
            $_POST['h']*$mult //how high the rectangle from the source image we want thumbnailed is
        );

        imagejpeg($img_dest,$path."thumbs/$model->image",$jpeg_quality);