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As an open source server-side scripting language, PHP can be used in many different types of Web development, among which the image preview function is very common and necessary. In web development, it is very important to provide image preview function, because it can help users better understand the required image information, improve user interaction experience and enhance the attractiveness of the website. This article will introduce how to implement image preview in php.
1. How to read images in PHP
Before implementing image preview, we first need to make it clear that image files are stored on the Web server, and In the PHP program, the image needs to be read through the server path.
In PHP, you can use the following method to read image files:
It should be noted that, When using the above three reading methods, the format of the image must be determined, otherwise it cannot be read correctly.
2. How to display images in PHP
There are several ways to display images in PHP:
For example:
<?php echo '<img src="./image.jpg">' ?>
For example:
<?php header('Content-Type:image/jpeg'); $file=fopen('./image.jpg','rb'); echo fread($file,filesize('./image.jpg')); fclose($file); ?>
For example:
<?php $image=imagecreatefromjpeg('./image.jpg'); header('Content-Type: image/jpeg'); imagejpeg($image); ?>
3. How to implement image preview in PHP
After understanding how to read and display images, implement Image preview becomes relatively easy. Two typical implementation methods are introduced below:
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<?php $img_path='./image.jpg'; $img_info=getimagesize($img_path); $width=$img_info[0]; $height=$img_info[1]; $mime=$img_info['mime']; header('Content-Type:'.$mime); $ratio=$width/$height; $new_width=200; $new_height=$new_width/$ratio; $image_resized=imagecreatetruecolor($new_width,$new_height); $image=imagecreatefromjpeg($img_path); imagecopyresampled($image_resized,$image,0,0,0,0,$new_width,$new_height,$width,$height); imagejpeg($image_resized); ?>The above code implements the function of reducing the image to a width of 200px and outputs it to the browser. Through the relevant functions of the GD library, functions such as changing the image size, cutting the image, rotating the image, etc. can be realized, and can be adjusted according to the needs. To sum up, implementing the image preview function in PHP mainly relies on reading and displaying images and the use of the GD library. Choose the appropriate implementation method according to specific needs, and pay attention to keeping the code concise and readable to achieve a better user experience.
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