理解 Noah's Classifieds/Image.php 源代码

<?php

   // GLOBALS
        // Setup our image creation/sampling tools
        $g_Createfg = array("", "ImageCreateFromGIF", "ImageCreateFromJPEG", "ImageCreateFromPNG");
        $g_Savefg = array("", "ImageGIF", "ImageJPEG", "ImagePNG");
        $g_Extensions = array("", "gif", "jpg", "png");
        $g_CheckBits = array(0, IMG_GIF, IMG_JPG, IMG_PNG);
        
function RatioImageSize($imageSize,$width,$height,$upscale = false)
{
        if (($imageSize[0] > $width || $imageSize[1] > $height) || $upscale)
        {
                $ratio = $imageSize[0]/$width;
                if( $imageSize[1]/$ratio > $height) $ratio=$imageSize[1]/$height;
                // Now copy over the new size
                $imageSize[0] = $imageSize[0]/$ratio;
                $imageSize[1] = $imageSize[1]/$ratio;
        }                       
        return $imageSize;                      
};

function array_to_str ($arr_input, $level=1){
   $str_return    = "array(\n";
   if ( is_array($arr_input) === false ){
           return    false;
   }
   foreach ( $arr_input as $key => $value ){
           for ( $i=0; $i<$level; $i++ ){
                   $str_return    .= "\t";
           }
           $str_return .= "[$key] => ";
           if ( is_array($value) ){
                   $str_return .= array_to_str ($value, $level+1);
           } else {
                   $str_return .= "$value\n";
           } 
   }
   for ( $i=0; $i<($level-1); $i++ ){
                   $str_return    .= "\t";
   }        
   return    $str_return.")\n";
};


class myImage
{
        var $size;
        var $type;
        var $imageData;
        var $imageName;
        var $supported; // Re-sizing supported?

        // Reads the actual image from disk, returns false if failure
        function ReadImage($imageName)
        {
                global $g_Createfg,$g_CheckBits;
                $this->imageName = $imageName;
        
                // Get the image's current size and file type
                $this->size = getimagesize($this->imageName);
                $this->type = $this->size[2];
                $this->imageData = "";     
                

                // Check if image resizing is supported and handling is supported by this php build for this specific extension
                if( defined("IMG_GIF") && function_exists("ImageTypes"))
                {
                        $this->supported = isset($g_CheckBits[$this->type]) && ((ImageTypes() & $g_CheckBits[$this->type]));               
                        
                        if ($this->supported)
                        {
                                // Read the image from file
                                $this->imageData = $g_Createfg[$this->type]($this->imageName);         
                                if (!$this->imageData) 
                                { // Image Creation Failed!!
                                        // Perhaps handle and error msg here if you want
                                        $this->supported = false;
                                }                       
                        }
                } 
                else  
                {
                        $this->$supported = false;
                        $this->imageData = false;
                }
                
                
           
           return $this->imageData;
        }
        
        // Creates an image on the local host with the new filename, remembering that the image is currently in a temporary folder
        function CreateLocal($targetName,$targetWidth,$targetHeight,$upscale=false)
        {       
                // Include required globals
                global $g_Createfg,$g_Savefg,$g_Extensions;
                
                if (($this->size[0] < $targetWidth) && ($this->size[1] < $targetHeight))
                {
                        // If no upscalling needed just copy the image
                        if ($upscale == false)
                                return copy($this->imageName,$targetName);
                                
                        // Upscale the image nonetheless

                }
                                
                // Get the new size
                $newSize = RatioImageSize($this->size,$targetWidth,$targetHeight,$upscale);
                
                // Does the newSize differ at all form the old size?
                if (($this->size[0] == $newSize[0]) && ($this->size[1] == $newSize[1]))
                        return copy($this->imageName,$targetName);
        
                // Image can't be resized, not supported    
                if (!$this->supported) return false;                 
                
                
                // Create the memory required for a true color image of size newSize
                $dst_im = ImageCreateTrueColor ($newSize[0], $newSize[1]);
                // Copy over the image data resampling
                imagecopyresampled ($dst_im, $this->imageData, 0, 0, 0, 0, $newSize[0], $newSize[1], $this->size[0], $this->size[1]);
                // Save the new image
                return $g_Savefg[$this->type]( $dst_im, $targetName);
        }       
        
}       
?>