我有一个制作图像的 PHP 文件。我将 PHP 配置为在屏幕上报告错误。当我在 Firefox 23 中运行 PHP 文件中的文件时，它返回 The Image cannot be displayed because it contains errors。

我如何找出图像中的特定错误？

代码如下:

<?php
    $tfont[] = 'cylburn-webfont.ttf';

    $cryptinstall = "./cryptographp.fct.php";
    include $cryptinstall;

    error_reporting(E_ALL ^ E_NOTICE);
    srand((double)microtime()*1000000);

    if ($_GET[$_GET['sn']] == "")
        unset ($_GET['sn']);

    session_start();

    include('getcaptcha.php');
    $question = getcaptcha();
    $questionLen = strlen($question);
    $cryptwidth  = 25 * $questionLen;

    $cryptinstall2 = "./cryptographp.cfg.php";
    include $cryptinstall;

    $cryptwidth = 900;
    $cryptheight = 200;

    // CrÈation du cryptogramme temporaire
    $imgtmp = imagecreatetruecolor($cryptwidth, $cryptheight);
    $blank  = imagecolorallocate($imgtmp, 255, 255, 255);
    $black   = imagecolorallocate($imgtmp, 0, 0, 0);
    imagefill($imgtmp, 0, 0, $blank);

    $word = '';
    $x = 10;
    $pair = rand(0, 1);
    $charnb = rand($charnbmin, $charnbmax);


    for ($i=0; $i<= $questionLen; $i++) {
         $tword[$i]['font'] =  $tfont[array_rand($tfont, 1)];
         $tword[$i]['angle'] = (rand(1, 2) == 1) ? rand(0, $charanglemax) : rand(360-$charanglemax, 360);

         $tword[$i]['element'] = str_split($question)[$i-1];

         $tword[$i]['size'] = rand($charsizemin, $charsizemax);
         $tword[$i]['y'] = ($charup ? ($cryptheight/2) + rand(0, ($cryptheight/5)) : ($cryptheight/1.5));
         $word .= $tword[$i]['element'];

         $lafont = "fonts/" . $tword[$i]['font'];
         imagettftext($imgtmp, $tword[$i]['size'], $tword[$i]['angle'], $x, $tword[$i]['y'], $black, $lafont, $tword[$i]['element']);

         $x += $charspace;
     }

    // Calculate horizontal racadrage temporary cryptogram
    $xbegin = 0;
    $x = 0;
    while (($x<$cryptwidth)and(!$xbegin)) {
        $y = 0;
        while (($y<$cryptheight) and (!$xbegin)) {
            if (imagecolorat($imgtmp, $x, $y) != $blank)
                $xbegin = $x;
            $y++;
        }
        $x++;
    }

    $xend = 0;
    $x = $cryptwidth-1;
    while (($x>0) and (!$xend)) {
        $y = 0;
        while (($y<$cryptheight)and(!$xend)) {
            if (imagecolorat($imgtmp, $x, $y) != $blank)
                $xend = $x;
            $y++;
        }
        $x--;
    }

    $xvariation = round(($cryptwidth/2)-(($xend-$xbegin)/2));
    imagedestroy ($imgtmp);

    // Create the final cryptogram
    // Create the background
    $img = imagecreatetruecolor($cryptwidth, $cryptheight);

    if ($bgimg and is_dir($bgimg)) {
        $dh  = opendir($bgimg);
        while (false !== ($filename = readdir($dh)))
            if(eregi(".[gif|jpg|png]$", $filename))
                $files[] = $filename;
                closedir($dh);
                $bgimg = $bgimg . '/' . $files[array_rand($files, 1)];
    }

    if ($bgimg) {
        list($getwidth, $getheight, $gettype, $getattr) = getimagesize($bgimg);
            $imgread = imagecreatefrompng($bgimg); break;
            imagecopyresized($img, $imgread, 0, 0, 0, 0, $cryptwidth, $cryptheight, $getwidth, $getheight);
            imagedestroy ($imgread);
        }
        else {
            $bg = imagecolorallocate($img, $bgR, $bgG, $bgB);
            imagefill($img, 0, 0, $bg);
            if ($bgclear)
                imagecolortransparent($img, $bg);
        }


    function ecriture()
    {
        // CrÈation de l'Ècriture
        global  $img, $ink, $charR, $charG, $charB, $charclear, $xvariation, $charnb, $charcolorrnd, $charcolorrndlevel, $tword, $charspace;
        $ink = imagecolorallocatealpha($img, $charR, $charG, $charB, $charclear);

        global $question;
        global $questionLen;

        $x = $xvariation;
        for ($i=1; $i<$questionLen; $i++) {

            if ($charcolorrnd) {   // Choisit des couleurs au hasard
                $ok = false;
                do {
                    $rndcolor = 0;
                    switch ($charcolorrndlevel) {
                        case 1 :
                            if ($rndcolor<200)
                                $ok = true; break; // tres sombre

                        default : $ok = true;
                    }
                } while (!$ok);

                $rndink = imagecolorallocatealpha($img, $rndR, $rndG, $rndB, $charclear);
            }

            $lafont = "fonts/" . $tword[$i]['font'];
            imagettftext($img, $tword[$i]['size'], $tword[$i]['angle'], $x, $tword[$i]['y'], $charcolorrnd ? $rndink : $ink, $lafont, $tword[$i]['element']);

            $x += $charspace;
        }
    }


    // Fonction permettant de dÈterminer la couleur du bruit et la forme du pinceau
    function noisecolor()
    {
        global $img, $noisecolorchar, $ink, $bg, $brushsize;
        switch ($noisecolorchar) {
            case 1  : $noisecol = $ink; break;
            case 2  : $noisecol = $bg; break;
            case 3  :
            default : $noisecol = imagecolorallocate ($img, 0, 0, 0); break;
        }

        if ($brushsize and $brushsize>1 and function_exists('imagesetbrush')) {
            $brush = imagecreatetruecolor($brushsize, $brushsize);
            imagefill($brush, 0, 0, $noisecol);
            imagesetbrush($img, $brush);
            $noisecol = IMG_COLOR_BRUSHED;
        }
        return $noisecol;
    }


    //Adding noise: points, lines and circles random
    function bruit()
    {
        global $noisepxmin, $noisepxmax, $noiselinemin, $noiselinemax, $nbcirclemin, $nbcirclemax, $img, $cryptwidth, $cryptheight;
        $nbpx = rand($noisepxmin, $noisepxmax);
        $nbline = rand($noiselinemin, $noiselinemax);
        for ($i=1; $i<$nbpx; $i++)
            imagesetpixel($img, rand(0, $cryptwidth-1), rand(0, $cryptheight-1), noisecolor());
            for ($i=1; $i<=$nbline; $i++)
                imageline($img, rand(0, $cryptwidth-1), rand(0, $cryptheight-1), rand(0, $cryptwidth-1), rand(0, $cryptheight-1), noisecolor());
    }


    if ($noiseup) {
        ecriture();
        bruit();
    }
    else {
        bruit();
        ecriture();
    }


    // Create the frame
    if ($bgframe) {
       $framecol = imagecolorallocate($img, ($bgR*3 + $charR)/4, ($bgG*3 + $charG)/4, ($bgB*3 + $charB)/4);
       imagerectangle($img, 0, 0, $cryptwidth-1, $cryptheight-1, $framecol);
    }


    // Transformations supplÈmentaires: Grayscale et Brouillage
    // VÈrifie si la fonction existe dans la version PHP installÈe
    if ($cryptgrayscal)
        imagefilter($img, IMG_FILTER_GRAYSCALE);
    if ($cryptgaussianblur)
        imagefilter($img, IMG_FILTER_GAUSSIAN_BLUR);

    /* If I comment out these lines, then the file runs fine, but
       of course it does not return an image.
    header("Content-type: image/png"); // This is the only header(...) that is
                                       // included in the file. I am requesting
                                       // the file directly with the URL.
    imagepng($img);

    imagedestroy ($img);
    unset ($word, $tword);
    unset ($_SESSION['cryptreload']); */
?>

如果我注释掉 header("content-type: image/png")，它会消除错误，但它会向浏览器返回无意义的内容，如下所示:

(综上所述，我对修复这个特定图像文件的兴趣不如了解如何调试图像创建文件中的错误/意外行为。我想学习如何修复我的图像生成文件中有问题的文件自己的。)

最佳答案

首先确保在 header() 命令输出任何内容之前，您的代码没有任何部分。

如果您的 header 之前有任何包含，请确保您没有使用 ?> 结束您的 PHP 代码，因为有时这会生成一个字节。

最后尝试将您的包含包装在 ob_start(); 和 ob_end_clean(); 中，因为这将确保不会因任何原因将随机字节强制转换为输出其他原因(我遇到过一次)。

关于php - 当 Firefox 显示 "the Image cannot be displayed because it contains errors"时，我如何找出错误是什么？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/18569495/