PHP generates verification code, PHP generates verification code

You will know it after reading it, you won’t hit me, don’t say much, let’s get started ( People don’t talk much)

1.0 First, look at the code

<span><span> 1</span> <?<span>php
</span><span> 2</span> <span>header</span>("Content-Type:text/html;Charset=UTF-8");<span>//</span><span> 設(shè)置頁面的編碼風(fēng)格</span>
<span> 3</span> <span>header</span>("Content-Type:image/jpeg");<span>//</span><span> 通知瀏覽器輸出的是jpeg格式的圖像</span>
<span> 4</span> 
<span> 5</span> <span>$img</span> = imagecreatetruecolor(150,50);<span>//</span><span>創(chuàng)建畫布并設(shè)置大小  x軸150  y軸50</span>
<span> 6</span> 
<span> 7</span> <span>$bgcolor</span> = imagecolorallocate(<span>$img</span>, <span>mt_rand</span>(0,255), <span>mt_rand</span>(0,255), <span>mt_rand</span>(0,255));<span>//</span><span>分配背景顏色</span>
<span> 8</span> imagefill(<span>$img</span>, 0, 0, <span>$bgcolor</span>); <span>//</span><span>//把背景填充到圖像</span>
<span> 9</span> imagejpeg(<span>$img</span>);             <span>//</span><span> 輸出圖像</span>
<span>10</span> imagedestroy(<span>$img</span>);          <span>//</span><span> 銷毀圖像</span>
<span>11</span> ?></span>

OK, now combine the above code to analyze the several functions used above:

①　imagecreatetruecolor();

imagecreatetruecolor — Create a new true color image (It feels so long. In fact, it’s easy to remember image/create/true/color if you look carefully. What is True color image? Look below)

<span><span>1</span> <span>resource</span> imagecreatetruecolor ( int <span>$width</span> , int <span>$height</span> )</span>

Both functions imagecreatetruecolor() and imagecreate() can create canvases

<span><span>1</span> <span>resource</span> imagecreate ( int <span>$x_size</span> , int <span>$y_size</span> )</span>

imagecreatetruecolor() creates a black image of size x and y (the default is black [even if it is called a true color image] ), If you want to change the background color, you need to use the fill color function imagefill($img,0,0,$color);

imagecreate Create a new blank image resource and use imagecolorAllocate() to add a background color

The above two functions are just two methods of the same function

②　imagecolorallocate();

imagecolorallocate — Assign a color to an image

<span><span>1</span> int imagecolorallocate ( <span>resource</span> <span>$image</span> , int <span>$red</span> , int <span>$green</span> , int <span>$blue</span> )</span>

The colors are red, green and blue respectively. These parameters are integers from 0 to 255 or hexadecimal 0x00 to 0xFF.

③　mt_rand();

mt_rand — Generate better random numbers

<span><span>1</span> int <span>mt_rand</span> ( int <span>$min</span> , int <span>$max</span> )</span>

$min Optional, the minimum value returned (default: 0) $max Optional, the maximum value returned (default: mt_getrandmax())

Here it is used to randomly generate the background color, with any value from 0-255. Therefore, the canvas background color is different even if the page is refreshed.

Rendering:

2.0　Start making interference lines and interference points inside. Prevent verification images from being recognized in seconds

<span><span> 1</span> <?<span>php
</span><span> 2</span> <span>header</span>("Content-Type:text/html;Charset=UTF-8");<span>//</span><span> 設(shè)置頁面的編碼風(fēng)格</span>
<span> 3</span> <span>header</span>("Content-Type:image/jpeg");<span>//</span><span> 通知瀏覽器輸出的是jpeg格式的圖像</span>
<span> 4</span> 
<span> 5</span> <span>$img</span> = imagecreatetruecolor(150,50);<span>//</span><span>創(chuàng)建畫布并設(shè)置大小  x軸150  y軸50</span>
<span> 6</span> 
<span> 7</span> <span>$bgcolor</span> = imagecolorallocate(<span>$img</span>, <span>mt_rand</span>(0,255), <span>mt_rand</span>(0,255), <span>mt_rand</span>(0,255));<span>//</span><span>分配背景顏色
</span><span> 8</span> 
<span> 9</span> <span>//添加干擾線，并循環(huán)3次，背景顏色隨機(jī)</span>
<span>10</span> <span>for</span>(<span>$i</span>=0;<span>$i</span><3;<span>$i</span>++<span>){
</span><span>11</span> 
<span>12</span>     <span>$linecolor</span> = imagecolorallocate(<span>$img</span>,<span>mt_rand</span>(0,255),<span>mt_rand</span>(0,255),<span>mt_rand</span>(0,255<span>));
</span><span>13</span>     imageline(<span>$img</span>, <span>mt_rand</span>(0,150), <span>mt_rand</span>(0,50), <span>mt_rand</span>(0,150), <span>mt_rand</span>(0,50), <span>$linecolor</span><span>);
</span><span>14</span> 
<span>15</span> <span>}
</span><span>16</span> <span>//</span><span>添加干擾點(diǎn)，并循環(huán)25次，背景顏色隨機(jī)</span>
<span>17</span> <span>for</span>(<span>$i</span>=0;<span>$i</span><25;<span>$i</span>++<span>){
</span><span>18</span> 
<span>19</span>     <span>$dotcolor</span> = imagecolorallocate(<span>$img</span>, <span>mt_rand</span>(0,255), <span>mt_rand</span>(0,255), <span>mt_rand</span>(0,255<span>));
</span><span>20</span>     imagesetpixel(<span>$img</span>, <span>mt_rand</span>(0,150), <span>mt_rand</span>(0,60), <span>$dotcolor</span><span>);
</span><span>21</span> 
<span>22</span> <span>}
</span><span>23</span> 
<span>24</span> imagefill(<span>$img</span>, 0, 0, <span>$bgcolor</span>); <span>//</span><span>//把背景填充到圖像</span>
<span>25</span> imagejpeg(<span>$img</span>);             <span>//</span><span> 輸出圖像</span>
<span>26</span> imagedestroy(<span>$img</span>);          <span>//</span><span> 銷毀圖像</span>
<span>27</span> ?></span>

Function analysis:

①　imageline();

imageline — Draw a line segment

<span><span>1</span> bool imageline ( <span>resource</span> <span>$image</span> , int <span>$x1</span> , int <span>$y1</span> , int <span>$x2</span> , int <span>$y2</span> , int <span>$color</span> )</span>

imageline() uses the color color to draw in the image image from the coordinates x1, y1 to x2, y2 (the upper left corner of the image is 0, 0) A line segment.

<span><em>imageline($img, mt_rand(0,150), mt_rand(0,50), mt_rand(0,150), mt_rand(0,50), $linecolor);<br /></em><br />這里意思就是 畫布$img 中從坐標(biāo) <code class="parameter">x1</code>，<code class="parameter">y1</code> 到 <code class="parameter">x2</code>，<code class="parameter">y2</code>隨機(jī)<br /></span>

②　　imagesetpixel();

imagesetpixel— 畫一個單一像素

<span><span>1</span> bool imagesetpixel ( <span>resource</span> <span>$image</span> , int <span>$x</span> , int <span>$y</span> , int <span>$color</span> )</span>

imagesetpixel() 在 image 圖像中用 color 顏色在 x，y 坐標(biāo)（圖像左上角為 0，0）上畫一個點(diǎn)。

<span><em>imagesetpixel($img, mt_rand(0,150), mt_rand(0,60), $dotcolor);<br /></em>具體含義同上<br /><br /></span>

效果圖：

3.0　　添加驗(yàn)證字母數(shù)字

<span><span> 1</span> <?<span>php
</span><span> 2</span> <span>header</span>("Content-Type:text/html;Charset=UTF-8");<span>//</span><span> 設(shè)置頁面的編碼風(fēng)格</span>
<span> 3</span> <span>header</span>("Content-Type:image/jpeg");<span>//</span><span> 通知瀏覽器輸出的是jpeg格式的圖像</span>
<span> 4</span> 
<span> 5</span> <span>$img</span> = imagecreatetruecolor(150,50);<span>//</span><span>創(chuàng)建畫布并設(shè)置大小  x軸150  y軸50</span>
<span> 6</span> 
<span> 7</span> <span>$bgcolor</span> = imagecolorallocate(<span>$img</span>, <span>mt_rand</span>(0,255), <span>mt_rand</span>(0,255), <span>mt_rand</span>(0,255));<span>//</span><span>分配背景顏色
</span><span> 8</span> 
<span> 9</span> <span>//添加干擾線，并循環(huán)3次，背景顏色隨機(jī)</span>
<span>10</span> <span>for</span>(<span>$i</span>=0;<span>$i</span><3;<span>$i</span>++<span>){
</span><span>11</span> 
<span>12</span>     <span>$linecolor</span> = imagecolorallocate(<span>$img</span>,<span>mt_rand</span>(0,255),<span>mt_rand</span>(0,255),<span>mt_rand</span>(0,255<span>));
</span><span>13</span>     imageline(<span>$img</span>, <span>mt_rand</span>(0,150), <span>mt_rand</span>(0,50), <span>mt_rand</span>(0,150), <span>mt_rand</span>(0,50), <span>$linecolor</span><span>);
</span><span>14</span> 
<span>15</span> <span>}
</span><span>16</span> <span>//</span><span>添加干擾點(diǎn)，并循環(huán)25次，背景顏色隨機(jī)</span>
<span>17</span> <span>for</span>(<span>$i</span>=0;<span>$i</span><25;<span>$i</span>++<span>){
</span><span>18</span> 
<span>19</span>     <span>$dotcolor</span> = imagecolorallocate(<span>$img</span>, <span>mt_rand</span>(0,255), <span>mt_rand</span>(0,255), <span>mt_rand</span>(0,255<span>));
</span><span>20</span>     imagesetpixel(<span>$img</span>, <span>mt_rand</span>(0,150), <span>mt_rand</span>(0,60), <span>$dotcolor</span><span>);
</span><span>21</span> 
<span>22</span> <span>}
</span><span>23</span> 
<span>24</span> <span>//</span><span>添加需要驗(yàn)證的字母或者數(shù)字</span>
<span>25</span> <span>$rand_str</span> = "qwertyuiopasdfghjklzxcvbnm1234567890";<span>//</span><span>需要使用到驗(yàn)證的一些字母和數(shù)字</span>
<span>26</span> <span>$str_arr</span> = <span>array</span>();    <span>//</span><span>命名一個數(shù)組</span>
<span>27</span> <span>for</span>(<span>$i</span> = 0;<span>$i</span><4;<span>$i</span>++){    <span>//</span><span>循環(huán)4次，就是有四個隨機(jī)的字母或者數(shù)字                            </span>
<span>28</span>     <span>$pos</span> = <span>mt_rand</span>(0,<span>strlen</span>(<span>$rand_str</span>)-1<span>);
</span><span>29</span>     <span>$str_arr</span>[] = <span>$rand_str</span>[<span>$pos</span>];<span>//</span><span>臨時交換</span>
<span>30</span> <span>}
</span><span>31</span> 
<span>32</span> <span>$x_start</span>=150/4;<span>//</span><span>單個字符X軸位置</span>
<span>33</span> 
<span>34</span> <span>foreach</span> (<span>$str_arr</span> <span>as</span> <span>$key</span><span>) {
</span><span>35</span>     <span>$fontcolor</span> = imagecolorallocate(<span>$img</span>, <span>mt_rand</span>(0,255), <span>mt_rand</span>(0,255), <span>mt_rand</span>(0,255<span>));
</span><span>36</span>     imagettftext(<span>$img</span>, 25, <span>mt_rand</span>(-15,15), <span>$x_start</span>, 50/2, <span>$fontcolor</span>, "C:/Windows/Fonts/Verdana.TTF", <span>$key</span><span>);
</span><span>37</span>     <span>$x_start</span> +=20;<span>//</span><span>遍歷后單個字符沿X軸 +20</span>
<span>38</span> <span>}
</span><span>39</span> 
<span>40</span> imagefill(<span>$img</span>, 0, 0, <span>$bgcolor</span>); <span>//</span><span>//把背景填充到圖像</span>
<span>41</span> imagejpeg(<span>$img</span>);             <span>//</span><span> 輸出圖像</span>
<span>42</span> imagedestroy(<span>$img</span>);          <span>//</span><span> 銷毀圖像</span>
<span>43</span> ?></span>

函數(shù):

imagettftext();

imagettftext — 用 TrueType 字體向圖像寫入文本

<span><span>1</span> <span>array</span> imagettftext ( <span>resource</span> <span>$image</span> , <span>float</span> <span>$size</span> , <span>float</span> <span>$angle</span> , int <span>$x</span> , int <span>$y</span> , int <span>$color</span> , <span>string</span> <span>$fontfile</span> , <span>string</span> <span>$text</span> )</span>

分析下面的代碼：

<span>imagettftext($img, 25, mt_rand(-15,15), $x_start, 50/2, $fontcolor, "C:/Windows/Fonts/Verdana.TTF", $key);</span>

?

$img-----------畫布

25-----------字體的尺寸。

mt_rand(-15,15)----------角度制表示的角度，0 度為從左向右讀的文本。更高數(shù)值表示逆時針旋轉(zhuǎn)。例如 90 度表示從下向上讀的文本。(就是字體角度的問題,)

$x_start----------通俗易懂的講就是字符的X軸位置

50/2----------字符的高度

$fontcolor----------字符顏色

"C:/Windows/Fonts/Verdana.TTF"----------字符的字體樣式路徑

$key-----------遍歷出后的字符

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效果：

看起來還是挺可愛的。

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