


Parsing the set of commonly used image image functions in PHP_PHP tutorial
gd_info函数:获取当前安装的GD库的信息
getimagesize函数:获取图像的大小
image_type_to_extension函数:获取图像类型的文件后缀
image_type_to_mime_type函数:判断一个IMAGETYPE常量的MIME类型
image2wbmp函数:以WBMP格式将图像输出到浏览器或文件
imagealphablending函数:设定图像的混色模式
imageantialias函数:是否使用antialias(抗锯齿)功能
imagearc函数:画椭圆弧
imagechar函数:水平地画一个字符
imagecharup函数:垂直地画一个字符
imagecolorallocate函数:为一幅图像分配颜色
imagecolorallocatealpha 函数:为一幅图像分配颜色+alpha
imagecolorat函数:获取某像素的颜色索引值
imagecolorclosest函数:获取与指定颜色最接近的颜色的索引值
imagecolorclosestalpha函数:获取与指定颜色加透明度最接近的颜色的索引值
imagecolorclosesthwb函数:获取与指定颜色最接近的色度的黑白色的索引
imagecolordeallocate函数:取消图像颜色的分配
imagecolorexact函数:获取指定颜色的索引值
imagecolorexactalpha函数:获取指定颜色加透明度的索引值
imagecolormatch函数:使一个图像中调色板版本的颜色与真彩色版本更能匹配
imagecolorresolve函数:获取指定颜色的索引值或有可能得到的最接近的替代值
imagecolorresolvealpha函数:获取指定颜色透明度的索引值或有可能得到的最接近的替代值
imagecolorset函数:给指定调色板索引设定颜色
imagecolorsforindex函数:获取某索引的颜色
imagecolorstotal函数:获取一幅图像的调色板中颜色的数目
imagecolortransparent函数:将某个颜色定义为透明色
imageconvolution函数:申请一个3*3的卷积矩阵
imagecopy函数:复制图像的一部分
imagecopymerge函数:复制并合并图像的一部分
imagecopymergegray函数:用灰度复制并合并图像的一部分
imagecopyresampled函数:重采样复制部分图像并调整大小
imagecopyresized函数:复制部分图像并调整大小
imagecreate函数:新建一个基于调色板的图像
imagecreatefromgd2 function: Create a new image from a GD 2 file or URL
imagecreatefromgd2part function: Create a new image from a part of a given GD 2 file or URL
imagecreatefromgd function: Create a new image from a GD file or URL An image
imagecreatefromgif function: Create a new image from a GIF file or URL
imagecreatefromjpeg function: Create a new image from a JPEG file or URL
imagecreatefrompng function: Create a new image from a PNG file or URL
imagecreatefromstring function: Create a new image from the image stream in the string
imagecreatefromwbmp function: Create a new image from a WBMP file or URL
imagecreatefromxbm function: Create a new image from an XBM file or URL
imagecreatefromxpm function: From Create a new image in an XPM file or URL
imagecreatetruecolor function: create a true color image
imagedashedline function: draw a dotted line
imagedestroy function: destroy an image
imageellipse function: draw an ellipse
imagefill Function: fill an area with the specified color
imagefilledarc function: draw an elliptical arc and fill it
imagefilledellipse function: draw an ellipse and fill it
imagefilledpolygon function: draw a polygon and fill it
imagefilledrectangle function: draw an Rectangle and fill it
imagefilltoborder function: fill the area until the border of the specified color
imagefilter function: use a filter on the image
imagefontheight function: get the font height
imagefontwidth function: get the font width
imageftbbox Function: gives a text box using FreeType2 font
imagefttext function: writes text to image using FreeType2 font
imagegammacorrect function: applies gamma correction to GD image
imagegd2 function: outputs GD 2 image to browser browser or file
imagegd function: output GD image to browser or file
imagegif function: output image in GIF format to browser or file
imageinterlace function: activate or disable interlacing
imageistruecolor Function: Check whether the image is a true color image
imagejpeg function: Output the image to a browser or file in JPEG format
imagelayereffect function: Set the alpha color mixing flag to use the bound libgd layering effect
imageline Function: draw a line segment
imageloadfont function: load a new font
imagepalettecopy function: copy the palette from one image to another
imagepng function: output the image to the browser in PNG format Or file
imagepolygon function: draw a polygon
imagepsbbox function: give a text box using PostScript Type1 font
imagepsencodefont function: change the character encoding vector in the font
imagepsextendfont function: expand or streamline the font
imagepsfreefont function: release the memory occupied by a PostScript Type1 font
imagepsloadfont function: load a PostScript Type1 font from a file
imagepsslantfont function: tilt a font
imagepstext function: use PostScript Type1 font to convert text The string is drawn on the image
imagerectangle function: draw a rectangle
imagerotate function: rotate the image with a given angle
imagesavealpha function: set the flag to save the complete alpha channel information when saving the PNG image
imagesetbrush function: set the brush image for drawing lines
imagesetpixel function: draw a single pixel
imagesetstyle function: set the style of line drawing
imagesetthickness function: set the width of line drawing
imagesettile Function: Set the texture used for filling
imagestring function: draw a line of string horizontally
imagestringup function: draw a line of string vertically
imagesx function: get the image width
imagesy function: get the image Height
imagetruecolortopalette function: Convert a true color image to a palette image
imagettfbbox function: Get the range of text using TrueType fonts
imagettftext function: Write text to an image with TrueType fonts
imagetypes function : Returns the image type supported by the current PHP version
imagewbmp function: Output the image to the browser or file in WBMP format
imagexbm function: Output the XBM image to the browser or file
iptcembed function: Convert the binary IPTC data is embedded in a JPEG image
iptcparse function: parses binary IPTC blocks into a single token
jpeg2wbmp function: converts a JPEG image file to a WBMP image file
png2wbmp function: converts a PNG image file to WBMP Image file

Effective methods to prevent session fixed attacks include: 1. Regenerate the session ID after the user logs in; 2. Use a secure session ID generation algorithm; 3. Implement the session timeout mechanism; 4. Encrypt session data using HTTPS. These measures can ensure that the application is indestructible when facing session fixed attacks.

Implementing session-free authentication can be achieved by using JSONWebTokens (JWT), a token-based authentication system where all necessary information is stored in the token without server-side session storage. 1) Use JWT to generate and verify tokens, 2) Ensure that HTTPS is used to prevent tokens from being intercepted, 3) Securely store tokens on the client side, 4) Verify tokens on the server side to prevent tampering, 5) Implement token revocation mechanisms, such as using short-term access tokens and long-term refresh tokens.

The security risks of PHP sessions mainly include session hijacking, session fixation, session prediction and session poisoning. 1. Session hijacking can be prevented by using HTTPS and protecting cookies. 2. Session fixation can be avoided by regenerating the session ID before the user logs in. 3. Session prediction needs to ensure the randomness and unpredictability of session IDs. 4. Session poisoning can be prevented by verifying and filtering session data.

To destroy a PHP session, you need to start the session first, then clear the data and destroy the session file. 1. Use session_start() to start the session. 2. Use session_unset() to clear the session data. 3. Finally, use session_destroy() to destroy the session file to ensure data security and resource release.

How to change the default session saving path of PHP? It can be achieved through the following steps: use session_save_path('/var/www/sessions');session_start(); in PHP scripts to set the session saving path. Set session.save_path="/var/www/sessions" in the php.ini file to change the session saving path globally. Use Memcached or Redis to store session data, such as ini_set('session.save_handler','memcached'); ini_set(

TomodifydatainaPHPsession,startthesessionwithsession_start(),thenuse$_SESSIONtoset,modify,orremovevariables.1)Startthesession.2)Setormodifysessionvariablesusing$_SESSION.3)Removevariableswithunset().4)Clearallvariableswithsession_unset().5)Destroythe

Arrays can be stored in PHP sessions. 1. Start the session and use session_start(). 2. Create an array and store it in $_SESSION. 3. Retrieve the array through $_SESSION. 4. Optimize session data to improve performance.

PHP session garbage collection is triggered through a probability mechanism to clean up expired session data. 1) Set the trigger probability and session life cycle in the configuration file; 2) You can use cron tasks to optimize high-load applications; 3) You need to balance the garbage collection frequency and performance to avoid data loss.


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