How to obtain network images and convert them to base64 in PHP

In website development and design, it is often necessary to use external images to enrich the content and aesthetics of the page. However, for some reasons, sometimes we need to convert network images to base64 string format. This article will introduce how to use PHP to obtain network images and convert them to base64 format.

1. Use PHP to obtain network images

First, we need to obtain the binary data of network images. In PHP, we can use the curl library to obtain network resources. Using the curl library requires the following steps:

1. Initialize curl:
Use the curl_init() function to initialize curl, which will return a curl handle that can be used for subsequent operations, such as obtaining resources and setting options etc. After initialization, curl options can be set using the curl_setopt() function.

$ch = curl_init();

2. Set curl options:
Set curl options to request network resources and obtain binary data. Options that need to be set include URL, request method, whether to include header information, etc.

curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_BINARYTRANSFER, true);

Among them, $url is the URL address of the network image to be obtained. The CURLOPT_RETURNTRANSFER option will return the content returned by the curl_exec() function as a string instead of directly outputting it. The CURLOPT_BINARYTRANSFER option will return the content without HTTP headers.

3. Execute the curl request:
Use the curl_exec() function to execute the curl request and return the response binary data.

$image_data = curl_exec($ch);

4. Close the curl resource handle:
Use the curl_close() function to close the curl resource handle.

curl_close($ch);

So far, we have used curl to obtain the binary data of network images. Next, we'll cover how to convert these binary data into base64 string format.

2. Convert binary data to base64 string format

PHP provides the base64_encode() function to convert binary data to base64 string format. The following is a simple example of using this function:

$image_base64 = base64_encode($image_data);

Here, $image_data is the binary data of the network image obtained in the previous step, and $image_base64 is the converted data in base64 string format. It is worth noting that the converted base64 string does not contain the prefix "data:image/png;base64,". If you need to add this prefix, you can use the following code:

$image_base64 = "data:image/png;base64," . base64_encode($image_data);

3. Convert the network image directly to base64 string format

In addition to using curl to obtain the binary data of network images, PHP also provides the file_get_contents() function to directly obtain network images and convert them to base64 string format. The code for using this method to obtain network images is very concise:

$image_data = file_get_contents($url);
$image_base64 = "data:image/png;base64," . base64_encode($image_data);

It should be noted that directly using the file_get_contents() function to obtain network resources will block the PHP process and should be processed in an asynchronous task to avoid affect subsequent operations.

To sum up, by using curl or file_get_contents function, we can convert network images into base64 string format to enrich our website design.

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