how do i debug PHP Image with print?

Question

i want to debug an php generated image algorithm with print. The problem is that it doesn't output the text i put in print. How can i output variables, so that i can debug? Thanks, Furtano

 public function drawPicture()
    {
        $im = imagecolorallocate ($this->picture, 255, 0, 255);
        imagettftext($this->picture, $this->fontSize , 0, 100, 100,$im , "cooperm.TTF", $this->name);



        # int ImageCopy ( resource $dst_im , resource $src_im , int $dst_x , int $dst_y , int $src_x , int $src_y , int $src_w , int $src_h )
        //imagecopy($this->picture, $this->pika, $this->wappen['pika']['dst_x'], $this->wappen['pika']['dst_y'], 0, 0, $this->pika_size[0], $this->pika_size[1]);

        $zufall = rand(1,99999999);

        #header("Content-Type: image/jpeg");
        imagepng($this->picture);

        $this->checkFontSize();

        imagedestroy($this->picture);

        print "WHY_DOESNT_PRINT?";


    }

Answer 1

You are sending a .png image to the browser, so the browser tries to display an image. The additional text is just seen as invalid image data and thus not displayed.

A solution to your problem would be using header() calls to send debug messages to your browser, or use Firefox+Firebug+ a PHP firebug adapter. Firebug works with headers to transmit information, so it's safe in image generation functions.

Answer 2

To debug using rorrorlog the point that the script that you want to see. The written files can be easily viewable.

Es:

error_log("\r\n debug " . implode("; ", $hc), 3, "errors.log"); // in case array
error_log("\r\n print " . $im, 3, "errors.log");