(Advanced) PHP image processing technology-GD library
1. Enable GD extension
extension=php_gd2.dll
Apache restart
2. Example:
Scenario:
Make a 500×300 green picture
①Create canvas
Canvas, a kind of resource data. Image resources that can be manipulated.
Create a new canvas (new)
ImageCreate(width, height), create a canvas based on the palette.
imageCreateTrueColor(width, height); Create a true color canvas.
Create canvas based on image (open)
imageCreateFromJPEG(image address);
imageCreateFromPNG(image address);
imageCreateFromGIF(image address);
②Operation canvas
Assign color: If you need to use a certain color on the canvas, you should assign the color to the canvas first.
Use function:
Color identification = imageColorAllocate(canvas, R, G, B);
Color representation:
RGB
③Fill the canvas: Fill (replace) the filling points with consecutive points with the same color
Use the function:
imageFill(canvas, filling position x, filling position Y, color Logo) Complete
The position is managed using coordinates:
Origin: 0, 0, the upper left corner of the canvas.
To the right, the x-axis increases, and down the Y-axis increases.
Coordinates of the lower right corner: width-1, height-1
④Output canvas
Output the processed pattern information in the canvas.
Typical:
1Output to image file.
2Direct output.
Use function:
imagePNG(canvas[, file address]):
imageJPEG();
imageGIF();
If there is no second parameter, it means direct output.
Note: If it is output directly to the browser, you need to inform the browser that the type of response data should be a PNG format image:
Use the command Content-type;
a The canvas can be output multiple times in various formats
⑤Destroy canvas resources
imageDestroy()
Sample code:
<?php //例如：制作500×300的绿色图片 $width=500; $height=300; //创建真彩色的画布 $img=imageCreateTrueColor($width,$height); // var_dump($img); //测试结果： resource(2) of type (gd) $img是一个资源类型 //使用函数imageColorAllocate(画布，R，G，B)分配颜色，颜色的表示方式：R G B $green=imageColorAllocate($img, 0x0, 0xff, 0x0); //填充画布，原点：0，0,画布的左上角，imageFill(画布, 填充位置x， 填充位置Y，颜色标识)完成 imageFill($img,0,0,$green); //输出画布，直接输出到当前路径下为图片文件，格式有PNG、JPEG、GIF //imagePNG($img,'./green.png'); //如果没有第二个参数，表示直接输出 //如果直接输出到浏览器，需要告知浏览器，响应数据的类型应该是PNG格式的图片：使用指令Content-type header('Content-Type:image/png;'); imagePNG($img); //注：一个画布可以输出多次，输出为各种格式 //销毁画布资源 imageDestroy($img);
Sample code:
<?php //例如：制作500×300的绿色图片 $width=500; $height=300; //创建真彩色的画布 $img=imageCreateTrueColor($width,$height); // var_dump($img); //测试结果： resource(2) of type (gd) $img是一个资源类型 //使用函数imageColorAllocate(画布，R，G，B)分配颜色，颜色的表示方式：R G B $green=imageColorAllocate($img, 0x0, 0xff, 0x0); //填充画布，原点：0，0,画布的左上角，imageFill(画布, 填充位置x， 填充位置Y，颜色标识)完成 imageFill($img,0,0,$green); //输出画布，直接输出到当前路径下为图片文件，格式有PNG、JPEG、GIF //imagePNG($img,'./green.png'); //如果没有第二个参数，表示直接输出 //如果直接输出到浏览器，需要告知浏览器，响应数据的类型应该是PNG格式的图片：使用指令Content-type header('Content-Type:image/png;'); imagePNG($img); //注：一个画布可以输出多次，输出为各种格式 //销毁画布资源 imageDestroy($img);
The above is the content of (Advanced) PHP image processing technology-GD library. For more related content, please pay attention to the PHP Chinese website (www.php.cn)!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
1671
14
1428
52
1329
25
1276
29
1256
24
PHP vs. Python: Understanding the Differences
Apr 11, 2025 am 12:15 AM
PHP and Python each have their own advantages, and the choice should be based on project requirements. 1.PHP is suitable for web development, with simple syntax and high execution efficiency. 2. Python is suitable for data science and machine learning, with concise syntax and rich libraries.
PHP: A Key Language for Web Development
Apr 13, 2025 am 12:08 AM
PHP is a scripting language widely used on the server side, especially suitable for web development. 1.PHP can embed HTML, process HTTP requests and responses, and supports a variety of databases. 2.PHP is used to generate dynamic web content, process form data, access databases, etc., with strong community support and open source resources. 3. PHP is an interpreted language, and the execution process includes lexical analysis, grammatical analysis, compilation and execution. 4.PHP can be combined with MySQL for advanced applications such as user registration systems. 5. When debugging PHP, you can use functions such as error_reporting() and var_dump(). 6. Optimize PHP code to use caching mechanisms, optimize database queries and use built-in functions. 7
PHP and Python: Comparing Two Popular Programming Languages
Apr 14, 2025 am 12:13 AM
PHP and Python each have their own advantages, and choose according to project requirements. 1.PHP is suitable for web development, especially for rapid development and maintenance of websites. 2. Python is suitable for data science, machine learning and artificial intelligence, with concise syntax and suitable for beginners.
PHP in Action: Real-World Examples and Applications
Apr 14, 2025 am 12:19 AM
PHP is widely used in e-commerce, content management systems and API development. 1) E-commerce: used for shopping cart function and payment processing. 2) Content management system: used for dynamic content generation and user management. 3) API development: used for RESTful API development and API security. Through performance optimization and best practices, the efficiency and maintainability of PHP applications are improved.
The Enduring Relevance of PHP: Is It Still Alive?
Apr 14, 2025 am 12:12 AM
PHP is still dynamic and still occupies an important position in the field of modern programming. 1) PHP's simplicity and powerful community support make it widely used in web development; 2) Its flexibility and stability make it outstanding in handling web forms, database operations and file processing; 3) PHP is constantly evolving and optimizing, suitable for beginners and experienced developers.
PHP and Python: Different Paradigms Explained
Apr 18, 2025 am 12:26 AM
PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.
PHP vs. Other Languages: A Comparison
Apr 13, 2025 am 12:19 AM
PHP is suitable for web development, especially in rapid development and processing dynamic content, but is not good at data science and enterprise-level applications. Compared with Python, PHP has more advantages in web development, but is not as good as Python in the field of data science; compared with Java, PHP performs worse in enterprise-level applications, but is more flexible in web development; compared with JavaScript, PHP is more concise in back-end development, but is not as good as JavaScript in front-end development.
PHP and Python: Code Examples and Comparison
Apr 15, 2025 am 12:07 AM
PHP and Python have their own advantages and disadvantages, and the choice depends on project needs and personal preferences. 1.PHP is suitable for rapid development and maintenance of large-scale web applications. 2. Python dominates the field of data science and machine learning.
