The idea of implementing a simple Chinese character verification code in PHP-PHP Tutorial-php.cn

The idea of implementing a simple Chinese character verification code in PHP

藏色散人

Release： 2023-04-07 13:06:01

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Nowadays, more and more websites have begun to use Chinese character verification codes, which not only increases the intimacy of our people, but also increases the difficulty of machine cracking. Here I will briefly explain it.

Create background canvas

$image = imagecreatetruecolor(200, 60);
$background = imagecolorallocate($image, 255, 255, 255);
imagefill($image, 0, 0, $background);

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Draw interference points

for ($i=0; $i < 300; $i++) { 
    $pixColor = imagecolorallocate($image, rand(150, 240), rand(150, 240), rand(150, 240));
    $pixX = rand(10, 190);
    $pixY = rand(5, 55);
    imagesetpixel($image, $pixX, $pixY, $pixColor);
}

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Draw interference lines

//4条水平线
for ($i=0; $i < 5; $i++) { 
    $lineColor = imagecolorallocate($image, rand(50, 150), rand(50, 150), rand(50, 150));
    $lineX1 = 0;
    $lineX2 = 300;
    $lineY1 = ($i + 1) * 12;
    $lineY2 = ($i + 1) * 12;
    imageline($image, $lineX1, $lineY1, $lineX2, $lineY2, $lineColor);
}
//10条垂直线
for ($i=0; $i < 30; $i++) { 
    $lineColor = imagecolorallocate($image, rand(50, 150), rand(50, 150), rand(50, 150));
    $lineX1 = ($i + 1) * 10;
    $lineX2 = ($i + 1) * 10;
    $lineY1 = 0;
    $lineY2 = 60;
    imageline($image, $lineX1, $lineY1, $lineX2, $lineY2, $lineColor);
}

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Drawing Chinese characters

$text = array(&#39;栀&#39;, &#39;子&#39;, &#39;花&#39;, &#39;开&#39;);
for ($i=0; $i < 4; $i++) {
    $textColor = imagecolorallocate($image, rand(20, 100), rand(20, 100), rand(20, 100));
    $textX = $i * 50 + 10;
    $textY = rand(40, 60);
    imagettftext($image, 30, rand(20, 50), $textX, $textY, $textColor, "/Library/Fonts/华文仿宋.ttf", $text[$i]);
}

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Note here, the font file must support Chinese

Encoding must use utf-8, do you remember to convert gbk Chinese? [iconv function can help you]

Output image

header("Content-Type:image/png");
imagepng($image);

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Destroy resources

imagedestroy($image);

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After a rough process, let’s do it , the Chinese verification code will be displayed. Of course, when a website is used, there will be a Chinese character library seed, from which a specific number of Chinese characters are randomly selected and displayed, and finally recorded in the session for verification.

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