此类提供以下方法：
1、强制裁剪，生成图片严格按照需要，不足放大，超过居中裁剪，图片始终铺满
2、和1类似，但不足的时候 不放大 会产生补白，可以用png消除。3、只缩放，不裁剪，保留全部图片信息，会产生补白，
4、只缩放，不裁剪，保留全部图片信息，生成图片大小为最终缩放后的图片有效信息的实际大小，不产生补白
<?php
/**
* mode 1 : 强制裁剪，生成图片严格按照需要，不足放大，超过裁剪，图片始终铺满
* mode 2 : 和1类似，但不足的时候 不放大 会产生补白，可以用png消除。
* mode 3 : 只缩放，不裁剪，保留全部图片信息，会产生补白，
* mode 4 : 只缩放，不裁剪，保留全部图片信息，生成图片大小为最终缩放后的图片有效信息的实际大小，不产生补白
* 默认补白为白色，如果要使补白成透明像素，请使用SaveAlpha()方法代替SaveImage()方法
*
* 调用方法：
*
* $img = new ImageCrop('old.jpg','afterCrop.jpg');
* $img->Crop(120,80,2);
* $img->SaveImage(); || $img->SaveAlpha();将补白变成透明像素保存
* $img->destory();
*
*
*/
class MyImageCrop
{
var $sImage;
var $dImage;
var $src_file;
var $dst_file;
var $src_width;
var $src_height;
var $src_ext;
var $src_type;
function __construct($src_file, $dst_file = '')
{
$this->src_file = $src_file;
$this->dst_file = $dst_file;
$this->LoadImage();
}
function LoadImage()
{
list($this->src_width, $this->src_height, $this->src_type) = getimagesize($this->src_file);
switch ($this->src_type)
{
case IMAGETYPE_JPEG :
$this->sImage = imagecreatefromjpeg($this->src_file);
$this->ext = 'jpg';
break;
case IMAGETYPE_PNG :
$this->sImage = imagecreatefrompng($this->src_file);
$this->ext = 'png';
break;
case IMAGETYPE_GIF :
$this->sImage = imagecreatefromgif($this->src_file);
$this->ext = 'gif';
break;
default:
exit();
}
}
function SaveImage($fileName = '')
{
$this->dst_file = $fileName ? $fileName : $this->dst_file;
switch ($this->src_type)
{
case IMAGETYPE_JPEG :
imagejpeg($this->dImage, $this->dst_file, 100);
break;
case IMAGETYPE_PNG :
imagepng($this->dImage, $this->dst_file);
break;
case IMAGETYPE_GIF :
imagegif($this->dImage, $this->dst_file);
break;
default:
break;
}
}
function OutImage()
{
switch ($this->src_type)
{
case IMAGETYPE_JPEG :
header('Content-type: image/jpeg');
imagejpeg($this->dImage);
break;
case IMAGETYPE_PNG :
header('Content-type: image/png');
imagepng($this->dImage);
break;
case IMAGETYPE_GIF :
header('Content-type: image/gif');
imagegif($this->dImage);
break;
default:
break;
}
}
function SaveAlpha($fileName = '')
{
$this->dst_file = $fileName ? $fileName . '.png' : $this->dst_file . '.png';
imagesavealpha($this->dImage, true);
imagepng($this->dImage, $this->dst_file);
}
function OutAlpha()
{
imagesavealpha($this->dImage, true);
header('Content-type: image/png');
imagepng($this->dImage);
}
function destory()
{
imagedestroy($this->sImage);
imagedestroy($this->dImage);
}
function Crop($dst_width, $dst_height, $mode = 1, $dst_file = '')
{
if ($dst_file)
$this->dst_file = $dst_file;
$this->dImage = imagecreatetruecolor($dst_width, $dst_height);
$bg = imagecolorallocatealpha($this->dImage, 255, 255, 255, 127);
imagefill($this->dImage, 0, 0, $bg);
imagecolortransparent($this->dImage, $bg);
$ratio_w = 1.0 * $dst_width / $this->src_width;
$ratio_h = 1.0 * $dst_height / $this->src_height;
$ratio = 1.0;
switch ($mode)
{
case 1: // always crop
if (($ratio_w < 1 && $ratio_h < 1) || ($ratio_w > 1 && $ratio_h > 1))
{
$ratio = $ratio_w < $ratio_h ? $ratio_h : $ratio_w;
$tmp_w = (int) ($dst_width / $ratio);
$tmp_h = (int) ($dst_height / $ratio);
$tmp_img = imagecreatetruecolor($tmp_w, $tmp_h);
$src_x = (int) (($this->src_width - $tmp_w) / 2);
$src_y = (int) (($this->src_height - $tmp_h) / 2);
imagecopy($tmp_img, $this->sImage, 0, 0, $src_x, $src_y, $tmp_w, $tmp_h);
imagecopyresampled($this->dImage, $tmp_img, 0, 0, 0, 0, $dst_width, $dst_height, $tmp_w, $tmp_h);
imagedestroy($tmp_img);
}
else
{
$ratio = $ratio_w < $ratio_h ? $ratio_h : $ratio_w;
$tmp_w = (int) ($this->src_width * $ratio);
$tmp_h = (int) ($this->src_height * $ratio);
$tmp_img = imagecreatetruecolor($tmp_w, $tmp_h);
imagecopyresampled($tmp_img, $this->sImage, 0, 0, 0, 0, $tmp_w, $tmp_h, $this->src_width, $this->src_height);
$src_x = (int) ($tmp_w - $dst_width) / 2;
$src_y = (int) ($tmp_h - $dst_height) / 2;
imagecopy($this->dImage, $tmp_img, 0, 0, $src_x, $src_y, $dst_width, $dst_height);
imagedestroy($tmp_img);
}
break;
case 2: // only small
if ($ratio_w < 1 && $ratio_h < 1)
{
$ratio = $ratio_w < $ratio_h ? $ratio_h : $ratio_w;
$tmp_w = (int) ($dst_width / $ratio);
$tmp_h = (int) ($dst_height / $ratio);
$tmp_img = imagecreatetruecolor($tmp_w, $tmp_h);
$src_x = (int) ($this->src_width - $tmp_w) / 2;
$src_y = (int) ($this->src_height - $tmp_h) / 2;
imagecopy($tmp_img, $this->sImage, 0, 0, $src_x, $src_y, $tmp_w, $tmp_h);
imagecopyresampled($this->dImage, $tmp_img, 0, 0, 0, 0, $dst_width, $dst_height, $tmp_w, $tmp_h);
imagedestroy($tmp_img);
}
elseif ($ratio_w > 1 && $ratio_h > 1)
{
$dst_x = (int) abs($dst_width - $this->src_width) / 2;
$dst_y = (int) abs($dst_height - $this->src_height) / 2;
imagecopy($this->dImage, $this->sImage, $dst_x, $dst_y, 0, 0, $this->src_width, $this->src_height);
}
else
{
$src_x = 0;
$dst_x = 0;
$src_y = 0;
$dst_y = 0;
if (($dst_width - $this->src_width) < 0)
{
$src_x = (int) ($this->src_width - $dst_width) / 2;
$dst_x = 0;
}
else
{
$src_x = 0;
$dst_x = (int) ($dst_width - $this->src_width) / 2;
}
if (($dst_height - $this->src_height) < 0)
{
$src_y = (int) ($this->src_height - $dst_height) / 2;
$dst_y = 0;
}
else
{
$src_y = 0;
$dst_y = (int) ($dst_height - $this->src_height) / 2;
}
imagecopy($this->dImage, $this->sImage, $dst_x, $dst_y, $src_x, $src_y, $this->src_width, $this->src_height);
}
break;
case 3: // keep all image size and create need size
if ($ratio_w > 1 && $ratio_h > 1)
{
$dst_x = (int) (abs($dst_width - $this->src_width) / 2);
$dst_y = (int) (abs($dst_height - $this->src_height) / 2);
imagecopy($this->dImage, $this->sImage, $dst_x, $dst_y, 0, 0, $this->src_width, $this->src_height);
}
else
{
$ratio = $ratio_w > $ratio_h ? $ratio_h : $ratio_w;
$tmp_w = (int) ($this->src_width * $ratio);
$tmp_h = (int) ($this->src_height * $ratio);
$tmp_img = imagecreatetruecolor($tmp_w, $tmp_h);
imagecopyresampled($tmp_img, $this->sImage, 0, 0, 0, 0, $tmp_w, $tmp_h, $this->src_width, $this->src_height);
$dst_x = (int) (abs($tmp_w - $dst_width) / 2);
$dst_y = (int) (abs($tmp_h - $dst_height) / 2);
imagecopy($this->dImage, $tmp_img, $dst_x, $dst_y, 0, 0, $tmp_w, $tmp_h);
imagedestroy($tmp_img);
}
break;
case 4: // keep all image but create actually size
if ($ratio_w > 1 && $ratio_h > 1)
{
$this->dImage = imagecreatetruecolor($this->src_width, $this->src_height);
imagecopy($this->dImage, $this->sImage, 0, 0, 0, 0, $this->src_width, $this->src_height);
}
else
{
$ratio = $ratio_w > $ratio_h ? $ratio_h : $ratio_w;
$tmp_w = (int) ($this->src_width * $ratio);
$tmp_h = (int) ($this->src_height * $ratio);
$this->dImage = imagecreatetruecolor($tmp_w, $tmp_h);
imagecopyresampled($this->dImage, $this->sImage, 0, 0, 0, 0, $tmp_w, $tmp_h, $this->src_width, $this->src_height);
}
break;
}
}
}
?>