本文实例讲述了php生成高清缩略图的方法。分享给大家供大家参考,具体如下:
在使用php的函数生成缩略图的使用,缩略图很多情况下都会失真,这个时候需要有一些对应的解决方法。
1.用imagecreatetruecolor和imageCopyreSampled函数分别取代imagecreate和imagecopyresized
2.给imagejpeg的第三个参数带上100(例:imagejpeg($ni,$toFile,100))
下面是具体的函数
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function CreateSmallImage( $OldImagePath , $NewImagePath , $NewWidth =154, $NewHeight =134)
{
// 取出原图,获得图形信息getimagesize参数说明:0(宽),1(高),2(1gif/2jpg/3png),3(width="638" height="340")
$OldImageInfo = getimagesize ( $OldImagePath );
if ( $OldImageInfo [2] == 1 ) $OldImg = @imagecreatefromgif( $OldImagePath );
elseif ( $OldImageInfo [2] == 2 ) $OldImg = @imagecreatefromjpeg( $OldImagePath );
else $OldImg = @imagecreatefrompng( $OldImagePath );
// 创建图形,imagecreate参数说明:宽,高
$NewImg = imagecreatetruecolor( $NewWidth , $NewHeight );
//创建色彩,参数:图形,red(0-255),green(0-255),blue(0-255)
$black = ImageColorAllocate( $NewImg , 0, 0, 0 ); //黑色
$white = ImageColorAllocate( $NewImg , 255, 255, 255 ); //白色
$red = ImageColorAllocate( $NewImg , 255, 0, 0 ); //红色
$blue = ImageColorAllocate( $NewImg , 0, 0, 255 ); //蓝色
$other = ImageColorAllocate( $NewImg , 0, 255, 0 );
//新图形高宽处理
$WriteNewWidth = $NewHeight *( $OldImageInfo [0] / $OldImageInfo [1]); //要写入的高度
$WriteNewHeight = $NewWidth *( $OldImageInfo [1] / $OldImageInfo [0]); //要写入的宽度
//这样处理图片比例会失调,但可以填满背景
if ( $OldImageInfo [0] / $NewWidth > $org_info [1] / $NewHeight ) {
$WriteNewWidth = $NewWidth ;
$WriteNewHeight = $NewWidth / ( $OldImageInfo [0] / $OldImageInfo [1]);
} else {
$WriteNewWidth = $NewHeight * ( $OldImageInfo [0] / $OldImageInfo [1]);
$WriteNewHeight = $NewHeight ;
}
//以$NewHeight为基础,如果新宽小于或等于$NewWidth,则成立
if ( $WriteNewWidth <= $NewWidth ) {
$WriteNewWidth = $WriteNewWidth ; //用判断后的大小
$WriteNewHeight = $NewHeight ; //用规定的大小
$WriteX = floor ( ( $NewWidth - $WriteNewWidth ) / 2 ); //在新图片上写入的X位置计算
$WriteY = 0;
} else {
$WriteNewWidth = $NewWidth ; // 用规定的大小
$WriteNewHeight = $WriteNewHeight ; //用判断后的大小
$WriteX = 0;
$WriteY = floor ( ( $NewHeight - $WriteNewHeight ) / 2 ); //在新图片上写入的X位置计算
}
//旧图形缩小后,写入到新图形上(复制),imagecopyresized参数说明:新旧, 新xy旧xy, 新宽高旧宽高
@imageCopyreSampled( $NewImg , $OldImg , $WriteX , $WriteY , 0, 0, $WriteNewWidth , $WriteNewHeight , $OldImageInfo [0], $OldImageInfo [1] );
//保存文件
// @imagegif( $NewImg, $NewImagePath );
@imagejpeg( $NewImg , $NewImagePath , 100);
//结束图形
@imagedestroy( $NewImg );
}
CreateSmallImage( "./images/jiexie.jpg" , "./images/jiexie.small.jpg" ,200,300);
CreateSmallImage( "./images/jiexie.jpg" , "./images/jiexie.middle.jpg" ,400,500);
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希望本文所述对大家php程序设计有所帮助。