Question

I’m trying to create a way to show an image created with PHP/GD, in an OOP fashion. In order to accomplish that, I created a class that, among other things, creates an image. Something like this:

<?php
    class MyClass 
    {
        public $image;
        function __construct()
        {
           ...
           $this->image = imagecreatetruecolor(100,100);
           $bg = imagecolorallocate($this->image,100,100,100);
           imagefilledrectangle($this->image,0,0,100,100,$bg);
           ...
        }
        ...
    }

    $myvar = new MyClass
?>

I tried to create a function within the class that would output the image. Something like this:

function show()
{
    echo "<img src='" . imagejpeg($this->image,100) . "' />";
}

but it didn’t work. I also tried

function show()
{
    echo "<img src='data:image/jpeg;base64," . imagejpeg($this->image,100) . "' />";
}

but this also didn’t work. The idea was to simply call the function from the HTML. Like this:

<div id='anyid'>
    <?php $myvar->show(); ?>
</div>

Am I going all wrong on this? Is there a way to accomplish what I want? I tried to think of a way to use the img=’mycode.php’ but it doesn’t work for me because the class has to be created before the page loads and the image appears half way through the page.

Thanks.

Answer 1

First, you need to insert a second parameter to imagejpeg() to allow 100 to be the quality parameter. Then, you need to base64-encode the raw bytes:

    public function show() {

        // Begin capturing the byte stream
        ob_start();

        // generate the byte stream
        imagejpeg($this->image, NULL, 100);

        // and finally retrieve the byte stream
        $rawImageBytes = ob_get_clean();

        echo "<img src='data:image/jpeg;base64," . base64_encode( $rawImageBytes ) . "' />";

    }

The data:image/jpeg;base64 requires the raw bytes to get encoded as base64.

Additionally, I’d propose to make $image a protected variable, since I suppose it is created and maintained solely inside of MyClass.