我有一个制作图像的 PHP 文件。我已将 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.
如何找出图像中的特定错误是什么？
这是代码：
<?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废话，如下所示：
（综上所述，我对修复这个特定的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。我想学习如何自己修复有问题的图像生成文件。）
