The image functions of the GD library are the easiest way to generate a persuasive image with text in PHP. In some circumstances, it is essential to make an image on the fly and write dynamic text to the image. Therefore, if you want to generate a dynamic casual image with PHP. So, you have to install the GD library. In this tutorial, we will explain to you how to create a dynamic image with PHP.

What is Application Programming Interface (APIs)?

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Our instance code will make a dynamic image with PHP grounded on the specified configuration. You can modify the image width, height, background color, text color, and text.

Create a Dynamic Image with PHP

The following code creates a random dynamic image using PHP. To create a dynamic image with PHP, we have to use the GD image functions.

imagecreate() – Creates a new image resource of specified size (width and hwight).
imagecolorallocate() – Allot a color for an image resource.
imagettfbbox() – Calculate the bounding box in pixels for TrueType text.
imagettftext() – Use TrueType fonts to write the text to the image.
imagepng() – Creates a PNG image.
imagedestroy() – Destroy an image resource.

// Specify font path
$font = 'fonts/verdana.ttf';

// Text font size
$font_size = 10;

// Get settings from URL
$setting = isset($_GET['s']) ? $_GET['s'] : "000_FFF_350_350";
$setting = explode("_", $setting);

$img = array();

// Define image width, height, and color
switch($n = count($setting)){
    case $n > 4 :
    case 3:
        $setting[3] = $setting[2];
    case 4:
        $img['width'] = (int) $setting[2];
        $img['height'] = (int) $setting[3];
    case 2:
        $img['background'] = $setting[0];
        $img['color'] = $setting[1];
        break;
    default:
        list($img['background'], $img['color'], $img['width'], $img['height']) = array('F', '0', 100, 100);
        break;
}
$background = explode(",",hex2rgb($img['background']));
$textColorRgb = explode(",",hex2rgb($img['color']));
$width = empty($img['width']) ? 100 : $img['width'];
$height = empty($img['height']) ? 100 : $img['height'];

// Get text from URL
$text = (string) isset($_GET['t']) ? urldecode($_GET['t']) : $width ." x ". $height;

// Create the image resource 
$image = @imagecreate($width, $height) or die("Cannot Initialize new GD image stream");

// Create image background
$background_color = imagecolorallocate($image, $background[0], $background[1], $background[2]);

// Grab the width & height of the text box
$bounding_box_size = imagettfbbox($font_size, 0, $font, $text);
$text_width = $bounding_box_size[2] - $bounding_box_size[0];
$text_height = $bounding_box_size[7]-$bounding_box_size[1];

// Text x&y coordinates
$x = ceil(($width - $text_width) / 2);
$y = ceil(($height - $text_height) / 2);

// Define text color
$text_color = imagecolorallocate($image, $textColorRgb[0], $textColorRgb[1], $textColorRgb[2]);

// Write text to image
imagettftext($image, $font_size, 0, $x, $y, $text_color, $font, $text);

// Set the content type header - in this case image/png
header('Content-Type: image/png');

// Output the image
imagepng($image);

// Free up memory
imagedestroy($image);

// Convert color code to rgb
function hex2rgb($hex) {
    $hex = str_replace("#", "", $hex);

    switch(strlen($hex)){
        case 1:
            $hex = $hex.$hex;
        case 2:
            $r = hexdec($hex);
            $g = hexdec($hex);
            $b = hexdec($hex);
            break;
        case 3:
            $r = hexdec(substr($hex,0,1).substr($hex,0,1));
            $g = hexdec(substr($hex,1,1).substr($hex,1,1));
            $b = hexdec(substr($hex,2,1).substr($hex,2,1));
            break;
        default:
            $r = hexdec(substr($hex,0,2));
            $g = hexdec(substr($hex,2,2));
            $b = hexdec(substr($hex,4,2));
            break;
    }

    $rgb = array($r, $g, $b);
    return implode(",", $rgb); 
}

Configure Options

s – Specify the image background color, width, foreground color, and height in the query string. And separate the setting by an underscore (_). (For example, 000_FFF_350_350)
t – Specify the text that you want to write on the image. By default, Write the image width and height over the image.

Usage

Stipulate the URL of the dynamic image generation script with the configuration option in the src tag.

<img src="create_image.php?s=000_FFF_350_350&t=Dynamic Image" >

Conclusion

Firstly, the dynamic image creation functionality is beneficial when you want to create a random photo on the fly for the Captcha code. Secondly, if you’re going to make the image transparent, don’t use the background colour. And at last, you can quickly spread our dynamic image generation code functionality as per your requirements.

Also, read our previous blog- Upload Multiple Images and Store in Database using PHP and MySQL

Tags: Dynamic Image Creation PHP