How to set font size in php

In web development, we usually need to set a larger font for some special text or titles than the main text to improve the readability and visual effects of the page. For web pages developed using PHP, we can set the font size through CSS style sheets, and we can also use PHP built-in functions to dynamically generate fonts with different styles.

1. Set the font size in the CSS style sheet

In a web page, we can control the style and layout of page elements through the style sheet, and the attribute that sets the font size is font- size. For example, if we want to double the font size of the title and make it bold at the same time, we can write it like this in the CSS style sheet:

h1 {
font-size: 2em;
font-weight: bold;
}

The 2em is the unit of font size. Its size is relative to the parent element or root element of the current element, rather than the absolute pixel value. At the same time, we can also use other scale units to specify the font size, such as px, pt, rem, etc.

2. PHP function to generate enlarged fonts

In addition to setting the font size in the CSS style sheet, we can also use PHP built-in functions to dynamically generate fonts of different styles. Below we introduce some commonly used functions.

1. imagettftext function

This function can draw a text on the picture and return an Image type image object. We can use this function to set different font sizes, colors, styles and other attributes for characters. For example, if we want to add a different font to the title than the text, it can be generated like this:

// Width and height of the image
$width = 400;
$height = 100;

// Create an empty canvas object
$image = imagecreatetruecolor($width, $height);

// Define the font size and color
$fontsize = 32;
$fontcolor = imagecolorallocate($image, 255, 0, 0);

// Define the path of the font file
$fontfile = 'fonts/arial.ttf';

/ / Draw text on the image
$text = "Hello World!";
imagettftext($image, $fontsize, 0, 0, $height/2, $fontcolor, $fontfile, $text);

//Output image
header('Content-Type: image/png');
imagepng($image);
imagedestroy($image);

In this In the example, we directly reference the Arial font file locally and use the imagettftext function to draw the customized text on the canvas. In addition, we can also set some font attributes for specific font files, such as character spacing, line spacing, etc.

2. gd_info function

This function can obtain relevant information about the GD library installed on the server, including the version of the GD library, supported image file formats, and Fonts directory Path, list of font files, etc. For example, if we want to know the list of font files that can be used on the server, we can use the following code:

$gd_info = gd_info();
$fonts_dir = $gd_info['GD_FONT_PATH'];
$ fonts_list = glob("$fonts_dir/*.ttf");

echo "Supported font file list:\n";
foreach ($fonts_list as $font) {
echo "- $font\n";
}

3. imageftbbox function

This function can calculate the space occupied by the given text in the specified font and return a Array containing the coordinates of the four vertices of the text. For example, we can use this function to precalculate the width occupied by the title, and then adjust it accordingly as needed to ensure that the page looks beautiful. Code example:

// Calculate font width and height
$fontsize = 32;
$fontfile = 'fonts/arial.ttf';
$text = "Hello World!";
$fontwidth = imagefontwidth($fontsize) * strlen($text);
$fontheight = imagefontheight($fontsize);
$box = imageftbbox($fontsize, 0, $fontfile, $text);
$fontwidth = $box[2] - $box[0];
$fontheight = $box[1] - $box[7];

Here we use imagefontwidth and imagefontheight Calculates the pixel values ​​used to set the width and height of the desired font. Their parameters are all font sizes.

Summary

The above is how to set amplified fonts in PHP, including setting the font size in the CSS style sheet and using PHP built-in functions to dynamically generate fonts of different styles. For different application scenarios, we can choose different ways to control font size and enhance the readability and aesthetics of page content.

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