问如何在JS / jQuery上实现透明背景的JPG和PNG的裁剪

EN

$x = $_GET["x"];
$y = $_GET["y"];
$w = $_GET["w"];
$h = $_GET["h"];

// Load the original image.
$img = imagecreatefrompng($img_path);
imagealphablending($img, true);

// Create a blank canvas for the cropped image.
$img_cropped = imagecreatetruecolor($w, $h);
imagesavealpha($img_cropped, true);
imagealphablending($img_cropped, false);
$transparent = imagecolorallocatealpha($img_cropped, 0, 0, 0, 127);
imagefill($img_cropped, 0, 0, $transparent);

// Crop the image and store the data on the blank canvas.
imagecopyresampled($img_cropped, $img, 0, 0, $x, $y, $w, $h, $w, $h); // or imagecopy()

// Save the image.
imagepng($img_cropped, "image_cropped.png", 2);

// Free memory.
imagedestroy($img);
imagedestroy($img_cropped);