scale an image proportionally without knowing both dimensions - php

Question

$newimg = imagecreatefromjpeg($tempname);
Now I need to scale this image proportionally but don't know both dimensions in advance.
$newimg = imagescale($newimg, 160, auto, IMG_BICUBIC); //doesn't work
or
$newimg = imagescale($newimg, auto, 160, IMG_BICUBIC); // doesn't work
Is there a way to say auto or something to calculate width or height automatically.
If no, how can I calculate this?
The accepted solution here doesn't work. I doesn't keep aspect ratio.

Answer 1

I made a function that will do what you need. I have tested this function with scaling down images and it works as intended.
This function will size an image preserving the aspect ratio to completely fit inside the dimensions that you specify. The image will also be centered.
The function also has the ability to crop. If you use the crop parameter, it will oversize the image to make sure the smallest side of the image fills the desired dimensions. It will then crop the image to fit inside the dimensions, thus completely filling the given dimensions. The image will be centered.
Here is the function:
function scaleMyImage($filePath, $newPath, $newSize, $crop = NULL){
$img = imagecreatefromstring(file_get_contents($filePath));
$dst_x = 0;
$dst_y = 0;
$width = imagesx($img);
$height = imagesy($img);
$newWidth = $newSize;
$newHeight = $newSize;
if($width < $height){ //Portrait.
if($crop){
$newWidth = floor($width * ($newSize / $width));
$newHeight = floor($height * ($newSize / $width));
$dst_y = (floor(($newHeight - $newSize)/2)) * -1;
}else{
$newWidth = floor($width * ($newSize / $height));
$newHeight = $newSize;
$dst_x = floor(($newSize - $newWidth)/2);
}
} elseif($width > $height) { //Landscape
if($crop){
$newWidth = floor($width * ($newSize / $height));
$newHeight = floor($height * ($newSize / $height));
$dst_x = (floor(($newWidth - $newSize)/2)) * -1;
}else{
$newWidth = $newSize;
$newHeight = floor($height * ($newSize / $width));
$dst_y = floor(($newSize - $newHeight)/2);
}
}
$finalImage = imagecreatetruecolor($newSize, $newSize);
imagecopyresampled($finalImage, $img, $dst_x, $dst_y, 0, 0, $newWidth, $newHeight, $width, $height);
imagejpeg($finalImage, $newPath, 60); //Set your compression.
imagedestroy($img);
imagedestroy($finalImage);
}
How to use:
$newSize = 160;
$filePath = 'path/myImg.jpg';
$newPath = 'path/newImg.jpg';
$crop = 1; //Set to NULL if you don't want to crop.
scaleMyImage($filePath, $newPath, $newSize, 1);
This should do exactly what you want with the crop parameter set to 1.

Answer 2

First of all you will have to mention al-least one dimension (either height or width) then using aspect ration of original image you can identify another. Here is a sample code which i used in my case:
$width = 160; // User-defined
$height = ''; // User-defined
$path = $uploadDir . '/' . $tempname;
$mime = getimagesize($path);
// Load original image
if($mime['mime']=='image/png') {
$orig_img = imagecreatefrompng($path);
}
if($mime['mime']=='image/jpg' || $mime['mime']=='image/jpeg' || $mime['mime']=='image/pjpeg') {
$orig_img = imagecreatefromjpeg($path);
}
// Get original image height and width
$width_orig = imagesx($orig_img);
$height_orig = imagesy($orig_img);
// Aspect ratio of original image
$aspectRatio = $width_orig / $height_orig;
// If any one dimension available then calculate other with the help of aspect-ratio of original image
if ($width == '' && $height != '') {
$newheight = $height;
$newwidth = round($height * $aspectRatio);
}
if ($width != '' && $height == '') {
$newheight = round($width / $aspectRatio);
$newwidth = $width;
}
$newimg = imagescale($orig_img, $newwidth, $newheight, IMG_BICUBIC);