How to solve the problem of Chinese garbled characters in php pictures

In PHP, we often need to operate some images, including adding Chinese text to the image. But sometimes, we may find that the Chinese text added in the image appears as garbled characters, which may be caused by encoding issues.

Solving this problem requires three steps: first, make sure that the input text and output image use the same character set; second, use the correct encoding in the string; finally, make sure that in PHP Handle character encoding correctly.

Step one: Confirm the character set

In PHP, we can use the mb_internal_encoding() function to set the default character set for PHP scripts. Before using this function, make sure the mbstring extension is installed and enabled. For example, to set the character set to utf-8, you can write code like the following:

<?php
mb_internal_encoding("utf-8");
?>

Before adding text to the image, you also need to set the transparency of the image by calling the function imagealphblending(). This function blends the image's color with its alpha value. For example, you could write:

<?php
$image = imagecreatetruecolor(400, 300);
$white = imagecolorallocate($image, 255, 255, 255);
imagefill($image, 0, 0, $white);
imagealphablending($image, false);
imagesavealpha($image, true);
?>

Step 2: Use the correct encoding

When adding text to an image, you need to make sure you use the correct encoding format. If the input text is encoded incorrectly, it may appear garbled.

In operating systems that support Unicode encoding, the commonly used encoding format is UTF-8. If you are using another encoding format, such as GBK or GB2312, the text will need to be converted. For example, you can use the function iconv() or mb_convert_encoding() to perform the conversion, as follows:

<?php
$text = "中文";
$convertedText = iconv("utf-8", "gbk", $text);
?>

Or:

<?php
$text = "中文";
$convertedText = mb_convert_encoding($text, "gbk", "utf-8");
?>

Step 3: Correctly handle character encoding

When adding text to an image, you need to ensure that character encoding is handled correctly. PHP provides many functions to help us handle character encoding.

For example, you can use the function imagettftext() to add text to an image, and the function mb_convert_encoding() to convert the text to the correct encoding.

Here is a sample code:

<?php
header("Content-type: image/png");
$im = imagecreatetruecolor(400, 300);
$white = imagecolorallocate($im, 255, 255, 255);
imagefill($im, 0, 0, $white);
$black = imagecolorallocate($im, 0, 0, 0);
$text = "中文";
$font = "arial.ttf";
$size = 20;
$text = mb_convert_encoding($text, "html-entities", "utf-8");
imagettftext($im, $size, 0, 50, 150, $black, $font, $text);
imagepng($im);
imagedestroy($im);
?>

In this example, we convert the text to "html-entities" format to ensure that it appears in the image with the correct encoding. We also used the imagettftext() function to add text to the image. This function needs to provide the size, rotation angle, font and other information of the text.

Summary

In PHP, processing Chinese text and images requires attention to some details. First, make sure that the PHP script and image use the same character set; second, use the correct encoding in the string; and finally, make sure character encoding is handled correctly in PHP.

If you encounter garbled code problems, you can troubleshoot according to the above methods. If the problem persists, please consider uploading the complete code or more details so others can help you find a solution.

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