會話與圖像不匹配PHP

Question

我想知道爲什麼由此腳本生成的圖像中的字符不匹配爲會話設置的字符。我找不到這是爲什麼，如果有人能夠幫助，那會很好。謝謝，Lea。

// Font directory + font name 
$font = 'wordpress/wp-content/themes/boldy/fonts/SF Juggernaut Bold.ttf'; 
// Total number of lines 
$lineCount = 20; 
// Size of the font 
$fontSize = 19; 
// Height of the image 
$height = 38; 
// Width of the image 
$width = 120; 
$img_handle = imagecreate ($width, $height) or die ("Cannot Create image"); 
// Set the Background Color RGB 
$backColor = imagecolorallocate($img_handle, 242, 242, 242); 
// Set the Line Color RGB 
$lineColor = imagecolorallocate($img_handle, 207, 207, 207); 
// Set the Text Color RGB 
$txtColor = imagecolorallocate($img_handle, 95, 95, 95); 

// Generate 
$string = "bcdefghijklmopqrstwxyz023456789"; 
for($i=0;$i<6;$i++){ 
    $pos = rand(0,36); 
    $str .= $string{$pos}; 
} 

$textbox = imagettfbbox($fontSize, 0, $font, $str) or die('Error in imagettfbbox function'); 

$x = ($width - $textbox[4])/2; 
$y = ($height - $textbox[5])/2; 

imagettftext($img_handle, $fontSize, 0, $x, $y, $txtColor, $font , $str) or die('Error in imagettftext function'); 

for($i=0;$i<$lineCount;$i++){ 
    $x1 = rand(0,$width);$x2 = rand(0,$width); 
    $y1 = rand(0,$width);$y2 = rand(0,$width); 
    imageline($img_handle,$x1,$y1,$x2,$y2,$lineColor); 
} 

header('Content-Type: image/jpeg'); 
imagejpeg($img_handle,NULL,100); 
imagedestroy($img_handle); 

session_start(); 
$_SESSION['img_number'] = $str; 

UPDATE：在測試中，我注意到，第一次加載圖像，會話沒有得到設定，從而使圖像被刷新時，會話設置與最後$ STR值

Answer 1

如果您的頭文件已經發送，您可能會遇到調用session_start（）的問題。

變化

header('Content-Type: image/jpeg'); 
imagejpeg($img_handle,NULL,100); 
imagedestroy($img_handle); 

session_start(); 
$_SESSION['img_number'] = $str; 

要

session_start(); 
header('Content-Type: image/jpeg'); 
imagejpeg($img_handle,NULL,100); 
imagedestroy($img_handle); 

$_SESSION['img_number'] = $str; 

Answer 2

如果您調試腳本的東西，如螢火蟲或devtools，然後調用圖像的兩倍。

嘗試禁用您的firebug/devtools，您將看到PROFIT。

Answer 3

session_start(); 

// Font directory + font name 
$font = 'wordpress/wp-content/themes/boldy/fonts/SF Juggernaut Bold.ttf'; 
// Total number of lines 
$lineCount = 20; 
// Size of the font 
$fontSize = 19; 
// Height of the image 
$height = 38; 
// Width of the image 
$width = 120; 
$img_handle = imagecreate ($width, $height) or die ("Cannot Create image"); 
// Set the Background Color RGB 
$backColor = imagecolorallocate($img_handle, 242, 242, 242); 
// Set the Line Color RGB 
$lineColor = imagecolorallocate($img_handle, 207, 207, 207); 
// Set the Text Color RGB 
$txtColor = imagecolorallocate($img_handle, 95, 95, 95); 

// Generate 
$string = "bcdefghijklmopqrstwxyz023456789"; 
$str = ''; 
for($i=0;$i<6;$i++){ 
    $pos = rand(0,36); 
    $str .= substr($string, $pos, 1); 
} 

$_SESSION['img_number'] = $str; 

$textbox = imagettfbbox($fontSize, 0, $font, $str) or die('Error in imagettfbbox function'); 

$x = ($width - $textbox[4])/2; 
$y = ($height - $textbox[5])/2; 

imagettftext($img_handle, $fontSize, 0, $x, $y, $txtColor, $font , $str) or die('Error in imagettftext function'); 

for($i=0;$i<$lineCount;$i++){ 
    $x1 = rand(0,$width);$x2 = rand(0,$width); 
    $y1 = rand(0,$width);$y2 = rand(0,$width); 
    imageline($img_handle,$x1,$y1,$x2,$y2,$lineColor); 
} 

header('Content-Type: image/jpeg'); 
imagejpeg($img_handle,NULL,100); 
imagedestroy($img_handle);