PHP Tutorials - Herong's Tutorial Examples - Version 5.00, by Dr. Herong Yang
GD Library - Create Transparent Image
This section provides a tutorial example on how to create an image with transparent background using GD Library functions.
If you want to create an image with a transparent background with the GD Library, here is what you need to remember:
1. Select a color for the background of the image. Make sure this background color is not used to draw any graphical element on the image.
2. Fill the entire image with the background color using imagefilledrectangle().
3. Draw all graphical elements on the image using imageline(), imageRectangle(), etc.
4. Set the background color to be transparent using imagecolortransparent().
5. Save the image in a format that supports transparent background like GIF or PNG.
Below is a PHP script that creates transparent background image in PNG format.
<?php # GD-Create-Transparent-Image.php #- Copyright (c) HerongYang.com. All Rights Reserved. $image = imagecreatetruecolor(400,400); $blue = imagecolorallocate($image, 0, 0, 255); $green = imagecolorallocate($image, 0, 255, 0); $red = imagecolorallocate($image, 255, 0, 0); $black = imagecolorallocate($image, 0, 0, 0); print("Fill the background...\n"); $bgColor = $black; imagefilledrectangle($image, 0, 0, 400, 400, $bgColor); print("Drawing some graphics...\n"); imagefilledrectangle($image, 50, 50, 350, 350, $blue); imagefilledellipse($image, 200, 200, 200, 200, $green); print("Open a circle to see the backgound...\n"); imagefilledellipse($image, 200, 200, 100, 100, $bgColor); print("Set the background to be transparent...\n"); imagecolortransparent($image, $bgColor); $file = "GD-Transparent-Graphics.png"; imagepng($image, $file); print("Image saved:\n"); print(" File: $file\n"); ?>
Run the above PHP script example:
php GD-Create-Transparent-Image.php Fill the background... Drawing some graphics... Open a circle to see the backgound... Set the background to be transparent... Image saved: File: GD-Transparent-Graphics.png
You should get an interesting transparent image.
Table of Contents
Introduction and Installation of PHP 7.3
PHP Data Types and Data Literals
Variables, References, and Constants
Expressions, Operations and Type Conversions
Conditional Statements - "if" and "switch"
Loop Statements - "while", "for", and "do ... while"
Function Declaration, Arguments, and Return Values
Introduction of Class and Object
Integrating PHP with Apache Web Server
Retrieving Information from HTTP Requests
Creating and Managing Sessions in PHP Scripts
Sending and Receiving Cookies in PHP Scripts
Controlling HTTP Response Header Lines in PHP Scripts
MySQL Server Connection and Access Functions
Functions to Manage Directories, Files and Images
SOAP Extension Function and Calling Web Services
SOAP Server Functions and Examples
Localization Overview of Web Applications
Using Non-ASCII Characters in HTML Documents
Using Non-ASCII Characters as PHP Script String Literals
Receiving Non-ASCII Characters from Input Forms
"mbstring" Extension and Non-ASCII Encoding Management
Managing Non-ASCII Character Strings with MySQL Servers
Configuring and Sending out Emails
GD Library - Draw Graphical Elements
GD Library - Print 2 Pictures on 1 Page
►GD Library - Create Transparent Image
Transparent Image Over Text Web Page
GD Library - Pad Transparent Image
Managing PHP Engine and Modules on macOS