php的GD库能否按百分比压缩图片?
用php的GD库压缩图片时,可以填入具体的宽和高进行压缩。那么,能否按百分比压缩呢,比如压缩为原图的90%,80%....等?
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用php的GD库压缩图片时,可以填入具体的宽和高进行压缩。那么,能否按百分比压缩呢,比如压缩为原图的90%,80%....等?
可以啊,中午刚给朋友搞了个压缩的,
<code> <?php /*+-----------------------------------------------------------------------+*/ /*+ jpg,gif,png图片等比例压缩 +*/ /*+-----------------------------------------------------------------------+*/ class RarImag{ /** * 得到等比例缩放的长宽 */ function getNewSize($maxWidth, $maxHeight, $srcWidth, $srcHeight) { if($srcWidth > $maxWidth) { $maxWidth = $maxWidth; if($srcHeight > $maxHeight) { $maxHeight = ($srcHeight/$srcHeight) * $maxWidth; } else { $maxHeight = $srcHeight; } return array('width' => $maxWidth,'height' => $maxHeight); } if($srcHeight > $maxHeight) { $maxHeight = $maxHeight; if($srcWidth > $maxWidth) { $maxWidth = ($srcWidth/$srcHeight) * $maxHeight; } else { $maxWidth = $srcWidth; } return array('width' => $srcWidth,'height' => $maxHeight); } return array('width' => $srcWidth,'height' => $srcHeight); } /** * 等比例生成缩略图 * * @param String $srcFile 原始文件路径 * @param String $dstFile 目标文件路径 * @param Integer $maxWidth 生成的目标文件的最大宽度 * @param Integer $maxHeight 生成的目标文件的最大高度 * @return Boolean 生成成功则返回true,否则返回false */ function makeThumb($srcFile, $dstFile, $maxWidth, $maxHeight) { if ($size = getimagesize($srcFile)) { $srcWidth = $size[0]; $srcHeight = $size[1]; $mime = $size['mime']; switch ($mime) { case 'image/jpeg'; $isJpeg = true; break; case 'image/gif'; $isGif = true; break; case 'image/png'; $isPng = true; break; default: return false; break; } //header("Content-type:$mime"); $arr = $this->getNewSize($maxWidth, $maxHeight, $srcWidth, $srcHeight); $thumbWidth = $arr['width']; $thumbHeight = $arr['height']; if (isset($isJpeg) && $isJpeg) { $dstThumbPic = imagecreatetruecolor($thumbWidth, $thumbHeight); $srcPic = imagecreatefromjpeg($srcFile); imagecopyresampled($dstThumbPic, $srcPic, 0, 0, 0, 0, $thumbWidth, $thumbHeight, $srcWidth, $srcHeight); imagejpeg($dstThumbPic, $dstFile, 100); imagedestroy($dstThumbPic); imagedestroy($srcPic); return true; } elseif (isset($isGif) && $isGif) { $dstThumbPic = imagecreatetruecolor($thumbWidth, $thumbHeight); //创建透明画布 imagealphablending($dstThumbPic, true); imagesavealpha($dstThumbPic, true); $trans_colour = imagecolorallocatealpha($dstThumbPic, 0, 0, 0, 127); imagefill($dstThumbPic, 0, 0, $trans_colour); $srcPic = imagecreatefromgif($srcFile); imagecopyresampled($dstThumbPic, $srcPic, 0, 0, 0, 0, $thumbWidth, $thumbHeight, $srcWidth, $srcHeight); imagegif($dstThumbPic, $dstFile); imagedestroy($dstThumbPic); imagedestroy($srcPic); return true; } elseif (isset($isPng) && $isPng) { $dstThumbPic = imagecreatetruecolor($thumbWidth, $thumbHeight); //创建透明画布 imagealphablending($dstThumbPic, true); imagesavealpha($dstThumbPic, true); $trans_colour = imagecolorallocatealpha($dstThumbPic, 0, 0, 0, 127); imagefill($dstThumbPic, 0, 0, $trans_colour); $srcPic = imagecreatefrompng($srcFile); imagecopyresampled($dstThumbPic, $srcPic, 0, 0, 0, 0, $thumbWidth, $thumbHeight, $srcWidth, $srcHeight); imagepng($dstThumbPic, $dstFile); imagedestroy($dstThumbPic); imagedestroy($srcPic); return true; } else { return false; } } else { return false; } } } ?></code>
imagejpeg() 有一个参数可以设定压缩比例
http://php.net/manual/zh/function.imagejpeg.php

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