PHP GD Lib是PHP中一個(gè)非常強(qiáng)大的圖像處理庫(kù)，它能夠處理各種各樣的圖像，比如創(chuàng)建縮略圖、加水印、裁剪、旋轉(zhuǎn)等操作，也支持將多幅圖像合并成一幅圖像。下面我將從以下幾個(gè)方面介紹PHP GD Lib。

第一：創(chuàng)建縮略圖

$src_img = "test.jpg";
$max_width = 200;
$max_height = 200;
$src_info = getimagesize($src_img);
$src_mime = $src_info['mime'];
switch ($src_mime) {
case 'image/jpeg':
$src_image = imagecreatefromjpeg($src_img);
break;
case 'image/png':
$src_image = imagecreatefrompng($src_img);
break;
case 'image/gif':
$src_image = imagecreatefromgif($src_img);
break;
default:
exit("Unsupported image type");
}
$src_width = imagesx($src_image);
$src_height = imagesy($src_image);
if (($max_width && $src_width >$max_width) || ($max_height && $src_height >$max_height)) {
if ($src_width >$src_height) {
$ratio = $max_width / $src_width;
} else {
$ratio = $max_height / $src_height;
}
$dst_width = $src_width * $ratio;
$dst_height = $src_height * $ratio;
$dst_image = imagecreatetruecolor($dst_width, $dst_height);
imagecopyresampled($dst_image, $src_image, 0, 0, 0, 0, $dst_width, $dst_height, $src_width, $src_height);
header('Content-Type: image/jpeg');
imagejpeg($dst_image);
} else {
header('Content-Type: ' . $src_mime);
readfile($src_img);
}

第二：添加水印

$src_img = "test.jpg";
$watermark_img = "watermark.png";
$watermark_pos = "bottom-right";
$watermark_padding = 10;
$src_info = getimagesize($src_img);
$src_mime = $src_info['mime'];
switch ($src_mime) {
case 'image/jpeg':
$src_image = imagecreatefromjpeg($src_img);
break;
case 'image/png':
$src_image = imagecreatefrompng($src_img);
break;
case 'image/gif':
$src_image = imagecreatefromgif($src_img);
break;
default:
exit("Unsupported image type");
}
$watermark_info = getimagesize($watermark_img);
$watermark_mime = $watermark_info['mime'];
switch ($watermark_mime) {
case 'image/jpeg':
$watermark_image = imagecreatefromjpeg($watermark_img);
break;
case 'image/png':
$watermark_image = imagecreatefrompng($watermark_img);
break;
case 'image/gif':
$watermark_image = imagecreatefromgif($watermark_img);
break;
default:
exit("Unsupported image type");
}
$src_width = imagesx($src_image);
$src_height = imagesy($src_image);
$watermark_width = imagesx($watermark_image);
$watermark_height = imagesy($watermark_image);
switch ($watermark_pos) {
case 'top-left':
$x = $watermark_padding;
$y = $watermark_padding;
break;
case 'top-right':
$x = $src_width - $watermark_width - $watermark_padding;
$y = $watermark_padding;
break;
case 'bottom-left':
$x = $watermark_padding;
$y = $src_height - $watermark_height - $watermark_padding;
break;
case 'bottom-right':
$x = $src_width - $watermark_width - $watermark_padding;
$y = $src_height - $watermark_height - $watermark_padding;
break;
default:
exit("Unsupported watermark position");
}
imagecopy($src_image, $watermark_image, $x, $y, 0, 0, $watermark_width, $watermark_height);
header('Content-Type: image/jpeg');
imagejpeg($src_image);

第三：裁剪圖像

$src_img = "test.jpg";
$x = 150;
$y = 150;
$width = 200;
$height = 200;
$src_info = getimagesize($src_img);
$src_mime = $src_info['mime'];
switch ($src_mime) {
case 'image/jpeg':
$src_image = imagecreatefromjpeg($src_img);
break;
case 'image/png':
$src_image = imagecreatefrompng($src_img);
break;
case 'image/gif':
$src_image = imagecreatefromgif($src_img);
break;
default:
exit("Unsupported image type");
}
$image_crop = imagecrop($src_image, ['x' =>$x, 'y' =>$y, 'width' =>$width, 'height' =>$height]);
header('Content-Type: image/jpeg');
imagejpeg($image_crop);

第四：旋轉(zhuǎn)圖像

$src_img = "test.jpg";
$degrees = 90;
$src_info = getimagesize($src_img);
$src_mime = $src_info['mime'];
switch ($src_mime) {
case 'image/jpeg':
$src_image = imagecreatefromjpeg($src_img);
break;
case 'image/png':
$src_image = imagecreatefrompng($src_img);
break;
case 'image/gif':
$src_image = imagecreatefromgif($src_img);
break;
default:
exit("Unsupported image type");
}
$rotated_image = imagerotate($src_image, $degrees, 0);
header('Content-Type: image/jpeg');
imagejpeg($rotated_image);

第五：將多幅圖像合并成一幅圖像

$src_images = [
"test1.jpg",
"test2.jpg",
"test3.jpg"
];
$src_info = getimagesize($src_images[0]);
$src_mime = $src_info['mime'];
$src_image_array = [];
foreach ($src_images as $src_img) {
switch ($src_mime) {
case 'image/jpeg':
$src_image_array[] = imagecreatefromjpeg($src_img);
break;
case 'image/png':
$src_image_array[] = imagecreatefrompng($src_img);
break;
case 'image/gif':
$src_image_array[] = imagecreatefromgif($src_img);
break;
default:
exit("Unsupported image type");
}
}
$dst_width = 800;
$dst_height = 600;
$dst_image = imagecreatetruecolor($dst_width, $dst_height);
$white = imagecolorallocate($dst_image, 255, 255, 255);
imagefill($dst_image, 0, 0, $white);
$x = 0;
$y = 0;
foreach ($src_image_array as $src_image) {
$src_width = imagesx($src_image);
$src_height = imagesy($src_image);
imagecopy($dst_image, $src_image, $x, $y, 0, 0, $src_width, $src_height);
$x += $src_width;
}
header('Content-Type: image/jpeg');
imagejpeg($dst_image);