将png转换为bmp格式

灰太狼 2022-06-16 02:08 378阅读 0赞

<?php
    $im = imagecreatefrompng("ok.png");
    imagebmp($im,'ok.bmp',24);
    
    
    //imagedestroy($im);
    
    
    /** 
    * 创建bmp格式图片 
    * 
    * @author: legend(legendsky@hotmail.com) 
    * @link: http://www.ugia.cn/?p=96 
    * @description: create Bitmap-File with GD library 
    * @version: 0.1 
    * 
    * @param resource $im             图像资源 
    * @param string      $filename       如果要另存为文件，请指定文件名，为空则直接在浏览器输出 
    * @param integer $bit            图像质量(1、4、8、16、24、32位) 
    * @param integer $compression 压缩方式，0为不压缩，1使用RLE8压缩算法进行压缩 
    * 
    * @return integer 
    */ 
    function imagebmp(&$im, $filename = '', $bit = 8, $compression = 0) 
    { 
           if (!in_array($bit, array(1, 4, 8, 16, 24, 32))) 
           { 
               $bit = 8; 
           } 
           else if ($bit == 32) // todo:32 bit 
           { 
               $bit = 24; 
           } 
    
    
           $bits = pow(2, $bit); 
        
           // 调整调色板 
           imagetruecolortopalette($im, true, $bits); 
           $width = imagesx($im); 
           $height = imagesy($im); 
           $colors_num = imagecolorstotal($im); 
        $rgb_quad = ''; 
           if ($bit <= 8) 
           { 
               // 颜色索引 
               //$rgb_quad = ''; 
               for ($i = 0; $i < $colors_num; $i ++) 
               { 
                   $colors = imagecolorsforindex($im, $i); 
                   $rgb_quad .= chr($colors['blue']) . chr($colors['green']) . chr($colors['red']) . "\0"; 
               } 
            
               // 位图数据 
               $bmp_data = ''; 
    
    
               // 非压缩 
               if ($compression == 0 || $bit < 8) 
               { 
                   if (!in_array($bit, array(1, 4, 8))) 
                   { 
                       $bit = 8; 
                   } 
    
    
                   $compression = 0; 
                
                   // 每行字节数必须为4的倍数，补齐。 
                   $extra = ''; 
                   $padding = 4 - ceil($width / (8 / $bit)) % 4; 
                   if ($padding % 4 != 0) 
                   { 
                       $extra = str_repeat("\0", $padding); 
                   } 
                
                   for ($j = $height - 1; $j >= 0; $j --) 
                   { 
                       $i = 0; 
                       while ($i < $width) 
                       { 
                           $bin = 0; 
                           $limit = $width - $i < 8 / $bit ? (8 / $bit - $width + $i) * $bit : 0; 
    
    
                           for ($k = 8 - $bit; $k >= $limit; $k -= $bit) 
                           { 
                               $index = imagecolorat($im, $i, $j); 
                               $bin |= $index << $k; 
                               $i ++; 
                           } 
    
    
                           $bmp_data .= chr($bin); 
                       } 
                    
                       $bmp_data .= $extra; 
                   } 
               } 
               // RLE8 压缩 
               else if ($compression == 1 && $bit == 8) 
               { 
                   for ($j = $height - 1; $j >= 0; $j --) 
                   { 
                       $last_index = "\0"; 
                       $same_num      = 0; 
                       for ($i = 0; $i <= $width; $i ++) 
                       { 
                           $index = imagecolorat($im, $i, $j); 
                           if ($index !== $last_index || $same_num > 255) 
                           { 
                               if ($same_num != 0) 
                               { 
                                   $bmp_data .= chr($same_num) . chr($last_index); 
                               } 
    
    
                               $last_index = $index; 
                               $same_num = 1; 
                           } 
                           else 
                           { 
                               $same_num ++; 
                           } 
                       } 
    
    
                       $bmp_data .= "\0\0"; 
                   } 
                
                   $bmp_data .= "\0\1"; 
               } 
    
    
               $size_quad = strlen($rgb_quad); 
               $size_data = strlen($bmp_data); 
           } 
           else 
           { 
               // 每行字节数必须为4的倍数，补齐。 
               $extra = ''; 
               $padding = 4 - ($width * ($bit / 8)) % 4; 
               if ($padding % 4 != 0) 
               { 
                   $extra = str_repeat("\0", $padding); 
               } 
    
    
               // 位图数据 
               $bmp_data = ''; 
    
    
               for ($j = $height - 1; $j >= 0; $j --) 
               { 
                   for ($i = 0; $i < $width; $i ++) 
                   { 
                       $index = imagecolorat($im, $i, $j); 
                       $colors = imagecolorsforindex($im, $index); 
                    
                       if ($bit == 16) 
                       { 
                           $bin = 0 << $bit; 
    
    
                           $bin |= ($colors['red'] >> 3) << 10; 
                           $bin |= ($colors['green'] >> 3) << 5; 
                           $bin |= $colors['blue'] >> 3; 
    
    
                           $bmp_data .= pack("v", $bin); 
                       } 
                       else 
                       { 
                           $bmp_data .= pack("c*", $colors['blue'], $colors['green'], $colors['red']); 
                       } 
                    
                       // todo: 32bit; 
                   } 
    
    
                   $bmp_data .= $extra; 
               } 
    
    
               $size_quad = 0; 
               $size_data = strlen($bmp_data); 
               $colors_num = 0; 
           } 
    
    
           // 位图文件头 
           $file_header = "BM" . pack("V3", 54 + $size_quad + $size_data, 0, 54 + $size_quad); 
    
    
           // 位图信息头 
           $info_header = pack("V3v2V*", 0x28, $width, $height, 1, $bit, $compression, $size_data, 0, 0, $colors_num, 0); 
        
           // 写入文件 
           if ($filename != '') 
           { 
               $fp = fopen($filename, "wb"); 
    
    
               fwrite($fp, $file_header); 
               fwrite($fp, $info_header); 
               fwrite($fp, $rgb_quad); 
               fwrite($fp, $bmp_data); 
               fclose($fp); 
    
    
               return 1; 
           } 
        
           // 浏览器输出 
           header("Content-Type: image/bmp"); 
           echo $file_header . $info_header; 
           echo $rgb_quad; 
           echo $bmp_data; 
        
           return 1; 
    }