PHP Manual: Copy and resize part of an image with resampling

Description

bool imagecopyresampled(
    GdImage $dst_image,
    GdImage $src_image,
    int $dst_x,
    int $dst_y,
    int $src_x,
    int $src_y,
    int $dst_width,
    int $dst_height,
    int $src_width,
    int $src_height
)

imagecopyresampled copies a rectangular portion of one image to another image, smoothly interpolating pixel values so that, in particular, reducing the size of an image still retains a great deal of clarity.

In other words, imagecopyresampled will take a rectangular area from src_image of width src_width and height src_height at position (src_x,src_y) and place it in a rectangular area of dst_image of width dst_width and height dst_height at position (dst_x,dst_y).

If the source and destination coordinates and width and heights differ, appropriate stretching or shrinking of the image fragment will be performed. The coordinates refer to the upper left corner. This function can be used to copy regions within the same image (if dst_image is the same as src_image) but if the regions overlap the results will be unpredictable.

Parameters

dst_image: Destination image resource.
src_image: Source image resource.
dst_x: x-coordinate of destination point.
dst_y: y-coordinate of destination point.
src_x: x-coordinate of source point.
src_y: y-coordinate of source point.
dst_width: Destination width.
dst_height: Destination height.
src_width: Source width.
src_height: Source height.

Return Values

Returns true on success or false on failure.

Changelog

Version	Description
8.0.0	`dst_image` and `src_image` expect GdImage instances now; previously, resources were expected.

Examples

Example #1 Simple example

This example will resample an image to half its original size.

<?php
// The file
$filename = 'test.jpg';
$percent = 0.5;

// Content type
header('Content-Type: image/jpeg');

// Get new dimensions
list($width, $height) = getimagesize($filename);
$new_width = $width * $percent;
$new_height = $height * $percent;

// Resample
$image_p = imagecreatetruecolor($new_width, $new_height);
$image = imagecreatefromjpeg($filename);
imagecopyresampled($image_p, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

// Output
imagejpeg($image_p, null, 100);
?>

The above example will output something similar to:

Example #2 Resampling an image proportionally

This example will display an image with the maximum width, or height, of 200 pixels.

<?php
// The file
$filename = 'test.jpg';

// Set a maximum height and width
$width = 200;
$height = 200;

// Content type
header('Content-Type: image/jpeg');

// Get new dimensions
list($width_orig, $height_orig) = getimagesize($filename);

$ratio_orig = $width_orig/$height_orig;

if ($width/$height > $ratio_orig) {
   $width = $height*$ratio_orig;
} else {
   $height = $width/$ratio_orig;
}

// Resample
$image_p = imagecreatetruecolor($width, $height);
$image = imagecreatefromjpeg($filename);
imagecopyresampled($image_p, $image, 0, 0, 0, 0, $width, $height, $width_orig, $height_orig);

// Output
imagejpeg($image_p, null, 100);
?>