功能：支持jpg,jpeg,gif,png,bmp图片格式，支持按原图片的比例进行缩放，可以选择在图片缩放的过程中是否需要对图片进行裁切，加入了图片质量控制，可以实现缩略图片质量最高化。完整类的代码如下：
<?php
/**
* 功能：php生成缩略图片的类
*/
class ResizeImage {
public $type; //图片类型
public $width; //实际宽度
public $height; //实际高度
public $resize_width; //改变后的宽度
public $resize_height; //改变后的高度
public $cut; //是否裁图
public $srcimg; //源图象
public $dstimg; //目标图象地址
public $im; //临时创建的图象
public $quality; //图片质量
function resizeimage($img, $wid, $hei, $c, $dstpath, $quality = 100) {
$this->srcimg = $img;
$this->resize_width = $wid;
$this->resize_height = $hei;
$this->cut = $c;
$this->quality = $quality;
$this->type = strtolower(substr(strrchr($this->srcimg, '.'), 1)); //图片的类型
$this->initi_img(); //初始化图象
$this->dst_img($dstpath); //目标图象地址
@$this->width = imagesx($this->im);
@$this->height = imagesy($this->im);
$this->newimg(); //生成图象
@ImageDestroy($this->im);
}
function newimg() {
$resize_ratio = ($this->resize_width) / ($this->resize_height); //改变后的图象的比例
@$ratio = ($this->width) / ($this->height); //实际图象的比例
if (($this->cut) == '1') { //裁图
if ($img_func === 'imagepng' && (str_replace('.', '', PHP_VERSION) >= 512)) { //针对php版本大于5.12参数变化后的处理情况
$quality = 9;
}
if ($ratio >= $resize_ratio) { //高度优先
$newimg = imagecreatetruecolor($this->resize_width, $this->resize_height);
imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, $this->resize_height, (($this->height) * $resize_ratio), $this->height);
imagejpeg($newimg, $this->dstimg, $this->quality);
}
if ($ratio < $resize_ratio) { //宽度优先
$newimg = imagecreatetruecolor($this->resize_width, $this->resize_height);
imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, $this->resize_height, $this->width, (($this->width) / $resize_ratio));
imagejpeg($newimg, $this->dstimg, $this->quality);
}
} else { //不裁图
if ($ratio >= $resize_ratio) {
$newimg = imagecreatetruecolor($this->resize_width, ($this->resize_width) / $ratio);
imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, ($this->resize_width) / $ratio, $this->width, $this->height);
imagejpeg($newimg, $this->dstimg, $this->quality);
}
if ($ratio < $resize_ratio) {
@$newimg = imagecreatetruecolor(($this->resize_height) * $ratio, $this->resize_height);
@imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, ($this->resize_height) * $ratio, $this->resize_height, $this->width, $this->height);
@imagejpeg($newimg, $this->dstimg, $this->quality);
}
}
}
function initi_img() { //初始化图象
if ($this->type == 'jpg' || $this->type == 'jpeg') {
$this->im = imagecreatefromjpeg($this->srcimg);
}
if ($this->type == 'gif') {
$this->im = imagecreatefromgif($this->srcimg);
}
if ($this->type == 'png') {
$this->im = imagecreatefrompng($this->srcimg);
}
if ($this->type == 'wbm') {
@$this->im = imagecreatefromwbmp($this->srcimg);
}
if ($this->type == 'bmp') {
$this->im = $this->ImageCreateFromBMP($this->srcimg);
}
}
function dst_img($dstpath) { //图象目标地址
$full_length = strlen($this->srcimg);
$type_length = strlen($this->type);
$name_length = $full_length - $type_length;
$name = substr($this->srcimg, 0, $name_length - 1);
$this->dstimg = $dstpath;
//echo $this->dstimg;
}
function ImageCreateFromBMP($filename) { //自定义函数处理bmp图片
if (!$f1 = fopen($filename, "rb")) returnFALSE;
$FILE = unpack("vfile_type/Vfile_size/Vreserved/Vbitmap_offset", fread($f1, 14));
if ($FILE['file_type'] != 19778) returnFALSE;
$BMP = unpack('Vheader_size/Vwidth/Vheight/vplanes/vbits_per_pixel' . '/Vcompression/Vsize_bitmap/Vhoriz_resolution' . '/Vvert_resolution/Vcolors_used/Vcolors_important', fread($f1, 40));
$BMP['colors'] = pow(2, $BMP['bits_per_pixel']);
if ($BMP['size_bitmap'] == 0) $BMP['size_bitmap'] = $FILE['file_size'] - $FILE['bitmap_offset'];
$BMP['bytes_per_pixel'] = $BMP['bits_per_pixel'] / 8;
$BMP['bytes_per_pixel2'] = ceil($BMP['bytes_per_pixel']);
$BMP['decal'] = ($BMP['width'] * $BMP['bytes_per_pixel'] / 4);
$BMP['decal']-= floor($BMP['width'] * $BMP['bytes_per_pixel'] / 4);
$BMP['decal'] = 4 - (4 * $BMP['decal']);
if ($BMP['decal'] == 4) $BMP['decal'] = 0;
$PALETTE = array();
if ($BMP['colors'] < 16777216) {
$PALETTE = unpack('V' . $BMP['colors'], fread($f1, $BMP['colors'] * 4));
}
$IMG = fread($f1, $BMP['size_bitmap']);
$VIDE = chr(0);
$res = imagecreatetruecolor($BMP['width'], $BMP['height']);
$P = 0;
$Y = $BMP['height'] - 1;
while ($Y >= 0) {
$X = 0;
while ($X < $BMP['width']) {
if ($BMP['bits_per_pixel'] == 24) $COLOR = unpack("V", substr($IMG, $P, 3) . $VIDE);
elseif ($BMP['bits_per_pixel'] == 16) {
$COLOR = unpack("n", substr($IMG, $P, 2));
$COLOR[1] = $PALETTE[$COLOR[1] + 1];
} elseif ($BMP['bits_per_pixel'] == 8) {
$COLOR = unpack("n", $VIDE . substr($IMG, $P, 1));
$COLOR[1] = $PALETTE[$COLOR[1] + 1];
} elseif ($BMP['bits_per_pixel'] == 4) {
$COLOR = unpack("n", $VIDE . substr($IMG, floor($P), 1));
if (($P * 2) % 2 == 0) $COLOR[1] = ($COLOR[1] >> 4);
else $COLOR[1] = ($COLOR[1] & 0x0F);
$COLOR[1] = $PALETTE[$COLOR[1] + 1];
} elseif ($BMP['bits_per_pixel'] == 1) {
$COLOR = unpack("n", $VIDE . substr($IMG, floor($P), 1));
if (($P * 8) % 8 == 0) $COLOR[1] = $COLOR[1] >> 7;
elseif (($P * 8) % 8 == 1) $COLOR[1] = ($COLOR[1] & 0x40) >> 6;
elseif (($P * 8) % 8 == 2) $COLOR[1] = ($COLOR[1] & 0x20) >> 5;
elseif (($P * 8) % 8 == 3) $COLOR[1] = ($COLOR[1] & 0x10) >> 4;
elseif (($P * 8) % 8 == 4) $COLOR[1] = ($COLOR[1] & 0x8) >> 3;
elseif (($P * 8) % 8 == 5) $COLOR[1] = ($COLOR[1] & 0x4) >> 2;
elseif (($P * 8) % 8 == 6) $COLOR[1] = ($COLOR[1] & 0x2) >> 1;
elseif (($P * 8) % 8 == 7) $COLOR[1] = ($COLOR[1] & 0x1);
$COLOR[1] = $PALETTE[$COLOR[1] + 1];
} else returnFALSE;
imagesetpixel($res, $X, $Y, $COLOR[1]);
$X++;
$P+= $BMP['bytes_per_pixel'];
}
$Y--;
$P+= $BMP['decal'];
}
fclose($f1);
return $res;
}
}
?>使用方法很简单代码如下：
$resizeimage=new ResizeImage('upload/abc.bmp', '120', '90', '0', 'upload/xabc.bmp');需要注意的是，如果在根目录的话，图片地址前面不要加"/"。要不是生成不了。
而且本代码的使用方式稍微开发一下，可以做批量生成缩略图用，生成速度超快。
