本文实例讲述了php使用GD创建保持宽高比缩略图的方法。分享给大家供大家参考。具体如下：* Create a thumbnail image from $inputFileName no taller or wider than* $maxSize. Returns the new image resource or false on error.* Author: mthorn.netfunction thumbnail($inputFileName, $maxSize = 100) $info = getimagesize($inputFileName); $type = isset($info['type']) $info['type'] : $info[2]; // Check support of file type if ( !(imagetypes() & $type) ) // Server does not support file type return false; $width = isset($info['width']) $info['width'] : $info[0]; $height = isset($info['height']) $info['height'] : $info[1]; // Calculate aspect ratio $wRatio = $maxSize / $width; $hRatio = $maxSize / $height; // Using imagecreatefromstring will automatically detect the file type $sourceImage = imagecreatefromstring(file_get_contents($inputFileName)); // Calculate a proportional width and height no larger than the max size. if ( ($width = $maxSize) && ($height = $maxSize) ) // Input is smaller than thumbnail, do nothing return $sourceImage; elseif ( ($wRatio * $height) $maxSize ) // Image is horizontal $tHeight = ceil($wRatio * $height); $tWidth = $maxSize; else // Image is vertical $tWidth = ceil($hRatio * $width); $tHeight = $maxSize; $thumb = imagecreatetruecolor($tWidth, $tHeight); if ( $sourceImage === false ) // Could not load image return false; // Copy resampled makes a smooth thumbnail imagecopyresampled($thumb,$sourceImage,0,0,0,0,$tWidth,$tHeight,$width,$height); imagedestroy($sourceImage); return $thumb;* Save the image to a file. Type is determined from the extension.* $quality is only used for jpegs.* Author: mthorn.netfunction imageToFile($im, $fileName, $quality = 80) if ( !$im || file_exists($fileName) ) return false; $ext = strtolower(substr($fileName, strrpos($fileName, '.'))); switch ( $ext ) case '.gif': imagegif($im, $fileName); break; case '.jpg': case '.jpeg': imagejpeg($im, $fileName, $quality); break; case '.png': imagepng($im, $fileName); break; case '.bmp': imagewbmp($im, $fileName); break; default: return false; return true;$im = thumbnail('temp.jpg', 100);imageToFile($im, 'temp-thumbnail.jpg');希望本文所述对大家的php程序设计有所帮助。PHP教程
