PHP实现图片裁剪与缩放的几种方法

图片裁剪缩放函数，支持方位裁剪和自定义坐标裁剪
/**
* 图片裁剪函数，支持指定定点裁剪和方位裁剪两种裁剪模式
* @param $src_file 原图片路径
* @param $new_width 裁剪后图片宽度（当宽度超过原图片宽度时，去原图片宽度）
* @param $new_height 裁剪后图片高度（当宽度超过原图片宽度时，去原图片高度）
* @param $type 裁剪方式，1-方位模式裁剪；0-定点模式裁剪。
* @param $pos 方位模式裁剪时的起始方位（当选定点模式裁剪时，此参数不起作用）
* 1为顶端居左，2为顶端居中，3为顶端居右；
* 4为中部居左，5为中部居中，6为中部居右；
* 7为底端居左，8为底端居中，9为底端居右；
* @param $start_x 起始位置X （当选定方位模式裁剪时，此参数不起作用）
* @param $start_y 起始位置Y（当选定方位模式裁剪时，此参数不起作用）
* @return 裁剪图片存储路径
*/
function thumb($src_file, $new_width, $new_height, $type = 1, $pos = 5, $start_x = 0, $start_y = 0) {
$pathinfo = pathinfo($src_file);
$dst_file = $pathinfo['dirname'] . '//m.sbmmt.com/m/' . $pathinfo['filename'] .'_'. $new_width . 'x' . $new_height . '.' . $pathinfo['extension'];
if (!file_exists($dst_file)) {
if ($new_width echo "params width or height error !";
exit();
}
if (!file_exists($src_file)) {
echo $src_file . " is not exists !";
exit();
}
// 图像类型
$img_type = exif_imagetype($src_file);
$support_type = array(IMAGETYPE_JPEG, IMAGETYPE_PNG, IMAGETYPE_GIF);
if (!in_array($img_type, $support_type, true)) {
echo "只支持jpg、png、gif格式图片裁剪";
exit();
}
/* 载入图像 */
switch ($img_type) {
case IMAGETYPE_JPEG :
$src_img = imagecreatefromjpeg($src_file);
break;
case IMAGETYPE_PNG :
$src_img = imagecreatefrompng($src_file);
break;
case IMAGETYPE_GIF :
$src_img = imagecreatefromgif($src_file);
break;
default:
echo "载入图像错误!";
exit();
}
/* 获取源图片的宽度和高度 */
$src_width = imagesx($src_img);
$src_height = imagesy($src_img);
/* 计算剪切图片的宽度和高度 */
$mid_width = ($src_width $mid_height = ($src_height /* 初始化源图片剪切裁剪的起始位置坐标 */
switch ($pos * $type) {
case 1://1为顶端居左
$start_x = 0;
$start_y = 0;
break;
case 2://2为顶端居中
$start_x = ($src_width - $mid_width) / 2;
$start_y = 0;
break;
case 3://3为顶端居右
$start_x = $src_width - $mid_width;
$start_y = 0;
break;
case 4://4为中部居左
$start_x = 0;
$start_y = ($src_height - $mid_height) / 2;
break;
case 5://5为中部居中
$start_x = ($src_width - $mid_width) / 2;
$start_y = ($src_height - $mid_height) / 2;
break;
case 6://6为中部居右
$start_x = $src_width - $mid_width;
$start_y = ($src_height - $mid_height) / 2;
break;
case 7://7为底端居左
$start_x = 0;
$start_y = $src_height - $mid_height;
break;
case 8://8为底端居中
$start_x = ($src_width - $mid_width) / 2;
$start_y = $src_height - $mid_height;
break;
case 9://9为底端居右
$start_x = $src_width - $mid_width;
$start_y = $src_height - $mid_height;
break;
default://随机
break;
}
// 为剪切图像创建背景画板
$mid_img = imagecreatetruecolor($mid_width, $mid_height);
//拷贝剪切的图像数据到画板，生成剪切图像
imagecopy($mid_img, $src_img, 0, 0, $start_x, $start_y, $mid_width, $mid_height);
// 为裁剪图像创建背景画板
$new_img = imagecreatetruecolor($new_width, $new_height);
//拷贝剪切图像到背景画板，并按比例裁剪
imagecopyresampled($new_img, $mid_img, 0, 0, 0, 0, $new_width, $new_height, $mid_width, $mid_height);
/* 按格式保存为图片 */
switch ($img_type) {
case IMAGETYPE_JPEG :
imagejpeg($new_img, $dst_file, 100);
break;
case IMAGETYPE_PNG :
imagepng($new_img, $dst_file, 9);
break;
case IMAGETYPE_GIF :
imagegif($new_img, $dst_file, 100);
break;
default:
break;
}
}
return ltrim($dst_file, '.');
}

list($src_w,$src_h)=getimagesize($src_img); // 获取原图尺寸
$dst_scale = $dst_h/$dst_w; //目标图像长宽比
$src_scale = $src_h/$src_w; // 原图长宽比

if($src_scale>=$dst_scale)
{
// 过高
$w = intval($src_w);
$h = intval($dst_scale*$w);
$x = 0;
$y = ($src_h - $h)/3;
}
else
{
// 过宽
$h = intval($src_h);
$w = intval($h/$dst_scale);
$x = ($src_w - $w)/2;
$y = 0;
}
// 剪裁
$source=imagecreatefromjpeg($src_img);
$croped=imagecreatetruecolor($w, $h);
imagecopy($croped,$source,0,0,$x,$y,$src_w,$src_h);
// 缩放
$scale = $dst_w/$w;
$target = imagecreatetruecolor($dst_w, $dst_h);
$final_w = intval($w*$scale);
$final_h = intval($h*$scale);
imagecopysampled($target,$croped,0,0,0,0,$final_w,$final_h,$w,$h);
// 保存
$timestamp = time();
imagejpeg($target, "$timestamp.jpg");
imagedestroy($target);
?>

$source_path string 源图路径

$target_width integer 目标图宽度

$target_height integer 目标图高度

支持图片类型: image/gif, image/jpeg, image/png.

function imagecropper($source_path, $target_width, $target_height)
{
$source_info = getimagesize($source_path);
$source_width = $source_info[0];
$source_height = $source_info[1];
$source_mime = $source_info['mime'];
$source_ratio = $source_height / $source_width;
$target_ratio = $target_height / $target_width;

// 源图过高
if ($source_ratio > $target_ratio)
{
$cropped_width = $source_width;
$cropped_height = $source_width * $target_ratio;
$source_x = 0;
$source_y = ($source_height - $cropped_height) / 2;
}
// 源图过宽
elseif ($source_ratio {
$cropped_width = $source_height / $target_ratio;
$cropped_height = $source_height;
$source_x = ($source_width - $cropped_width) / 2;
$source_y = 0;
}
// 源图适中
else
{
$cropped_width = $source_width;
$cropped_height = $source_height;
$source_x = 0;
$source_y = 0;
}

switch ($source_mime)
{
case 'image/gif':
$source_image = imagecreatefromgif($source_path);
break;

case 'image/jpeg':
$source_image = imagecreatefromjpeg($source_path);
break;

case 'image/png':
$source_image = imagecreatefrompng($source_path);
break;

default:
return false;
break;
}

$target_image = imagecreatetruecolor($target_width, $target_height);
$cropped_image = imagecreatetruecolor($cropped_width, $cropped_height);

// 裁剪
imagecopy($cropped_image, $source_image, 0, 0, $source_x, $source_y, $cropped_width, $cropped_height);
// 缩放
imagecopyresampled($target_image, $cropped_image, 0, 0, 0, 0, $target_width, $target_height, $cropped_width, $cropped_height);

header('Content-Type: image/jpeg');
imagejpeg($target_image);
imagedestroy($source_image);
imagedestroy($target_image);
imagedestroy($cropped_image);
}