创建图像缩略图并将其缓存在PHP中
创建图像缩略图是很常见的做法，并且有一些脚本可让您使用GD2库在PHP中执行此操作。但是，对于通常应该做的简单任务来说，它们通常是多余的，因此在进行一些搜索和测试后，我发现了以下ImageResize类，该类来自http://shiege.com/scripts/thumbnail/。我已将代码修改为PHP5，但如果要使用PHP4版本，则可以从网站上获取它。
class ImageResize
{
public $img;
public function ImageResize($imgfile)
{
//检测图像格式
$this->img["format"] = ereg_replace(".*\.(.*)$","\\1",$imgfile);
$this->img["format"] = strtoupper($this->img["format"]);
if($this->img["format"] == "JPG" || $this->img["format"] == "JPEG"){
//JPEG
$this->img["format"] = "JPEG";
$this->img["src"] = ImageCreateFromJPEG ($imgfile);
}elseif($this->img["format"] == "PNG"){
//PNG
$this->img["format"] = "PNG";
$this->img["src"] = ImageCreateFromPNG ($imgfile);
}elseif($this->img["format"] == "GIF"){
//GIF
$this->img["format"] = "GIF";
$this->img["src"] = ImageCreateFromGif($imgfile);
} elseif ($this->img["format"] == "WBMP"){
//WBMP
$this->img["format"] = "WBMP";
$this->img["src"] = ImageCreateFromWBMP ($imgfile);
} else {
//DEFAULT
echo "Not Supported File";
exit();
};
$this->img["lebar"] = imagesx($this->img["src"]);
$this->img["tinggi"] = imagesy($this->img["src"]);
//默认质量jpeg
$this->img["quality"] = 75;
}
public function size_height($size = 100)
{
//height
$this->img["tinggi_thumb"] = $size;
$this->img["lebar_thumb"] = ($this->img["tinggi_thumb"]/$this->img["tinggi"])*$this->img["lebar"];
}
public function size_width($size = 100)
{
//width
$this->img["lebar_thumb"] = $size;
$this->img["tinggi_thumb"] = ($this->img["lebar_thumb"]/$this->img["lebar"])*$this->img["tinggi"];
}
public function size_auto($size = 100)
{
//size
if($this->img["lebar"]> = $this->img["tinggi"]){
$this->img["lebar_thumb"] = $size;
$this->img["tinggi_thumb"] = ($this->img["lebar_thumb"]/$this->img["lebar"])*$this->img["tinggi"];
}else{
$this->img["tinggi_thumb"] = $size;
$this->img["lebar_thumb"] = ($this->img["tinggi_thumb"]/$this->img["tinggi"])*$this->img["lebar"];
};
}
public function jpeg_quality($quality = 75)
{
//jpeg品质
$this->img["quality"] = $quality;
}
public function show()
{
//显示拇指
header("Content-Type: image/".$this->img["format"]);
/* change ImageCreateTrueColor to ImageCreate if your GD not supported ImageCreateTrueColor function*/
$this->img["des"] = ImageCreateTrueColor($this->img["lebar_thumb"],$this->img["tinggi_thumb"]);
imagecopyresampled($this->img["des"], $this->img["src"], 0, 0, 0, 0, $this->img["lebar_thumb"], $this->img["tinggi_thumb"], $this->img["lebar"], $this->img["tinggi"]);
if ($this->img["format"] == "JPG" || $this->img["format"] == "JPEG"){
//JPEG
imageJPEG($this->img["des"],"",$this->img["quality"]);
}elseif($this->img["format"] == "PNG"){
//PNG
imagePNG($this->img["des"]);
}elseif($this->img["format"] == "GIF"){
//GIF
imageGIF($this->img["des"]);
}elseif($this->img["format"] == "WBMP"){
//WBMP
imageWBMP($this->img["des"]);
};
}
public function save($save = "")
{
//节省拇指
if (empty($save)) {
$save = strtolower("./thumb.".$this->img["format"]);
}
/* change ImageCreateTrueColor to ImageCreate if your GD not supported ImageCreateTrueColor function*/
$this->img["des"] = ImageCreateTrueColor($this->img["lebar_thumb"],$this->img["tinggi_thumb"]);
imagecopyresampled($this->img["des"], $this->img["src"], 0, 0, 0, 0, $this->img["lebar_thumb"], $this->img["tinggi_thumb"], $this->img["lebar"], $this->img["tinggi"]);
if ($this->img["format"] == "JPG" || $this->img["format"] == "JPEG") {
//JPEG
imageJPEG($this->img["des"],"$save",$this->img["quality"]);
} elseif ($this->img["format"] == "PNG") {
//PNG
imagePNG($this->img["des"],"$save");
} elseif ($this->img["format"] == "GIF") {
//GIF
imageGIF($this->img["des"],"$save");
} elseif ($this->img["format"] == "WBMP") {
//WBMP
imageWBMP($this->img["des"],"$save");
};
}
}将其放入一个名为class.ImageResize.php的文件中，您可以使用它来调整大小并显示所需的任何图像。
include('class.ImageResize.php');
//创建ImageResize对象
$originalImage = new ImageResize("anImage.jpg");
//使用显示功能将该图像打印到屏幕上
$originalImage->show();
//使用保存功能将此图像保存到另一个文件-保留空白以另存为thumb.anImage.jpg
$originalImage->save("anotherFile.png");
//使用尺寸功能之一调整图像尺寸
$originalImage->size_width(120);
//再次保存...
$originalImage->save("thumb_anotherFile.png");如果要创建简单的缩略图缓存功能，则可以使用以下代码。它检查图像是否存在以及是否早于30天。如果是，则删除该文件，并且由于该文件不再存在（或者从不存在），将运行创建缩略图的代码的下一部分。
$imageName = str_replace(dirname("./images/", "" , "http://www.example.com/images/an_image.jpg");
if (file_exists("./thumb_cache" . $imageName)) {
//2592000=30天
if ( time() - filemtime("./thumb_cache".$imageName) > 2592000 ) {
unlink("./thumb_cache".$imageName);
}
}
if (!file_exists("./thumb_cache" . $imageName)) {
include('class.ImageResize.php');
//如果缓存文件不存在，则创建它。
$originalImage = new ImageResize("./images/" . $_result['image_path']);
$originalImage->size_width(120);
$originalImage->save("./thumb_cache".$imageName);
}