PHP在扩展类中使用外部变量

Question

I'm using TCPDF to make an award generator. It checks the type of award and based on that it fills in the image_path variable (and some other variables that had nothing to do with this question.

switch($award){
    case 25:
        $img_file = '../../img/award_25.png';
        break;
    case 50:
        $img_file = '../../img/award_50.png';
        break;
    ... and so on ...
}

A little further, as seen in example_051 of TCPDF they extend the class to define the background image. The path to that image is the one that is in the variable $img_file created above.

require_once('tcpdf_include.php');
class MYPDF extends TCPDF {
    public function Header() {
        // get the current page break margin
        $bMargin = $this->getBreakMargin();
        // get current auto-page-break mode
        $auto_page_break = $this->AutoPageBreak;
        // disable auto-page-break
        $this->SetAutoPageBreak(false, 0);
        // margins Left, Top, Right, Bottom in pixels
        $this->Image($img_file, -9, -8, 316, 225, '', '', '', false, 300, '', false, false, 0);
        // restore auto-page-break status
        $this->SetAutoPageBreak($auto_page_break, $bMargin);
        // set the starting point for the page content
        $this->setPageMark();
    }
}

Due to the scope the variable $image_file is not known within the extend. Is there a way I could make this work?

Thanks in advance!

Answer 1

class MYPDF extends TCPDF {
protected $img_file;
 public function __construct($img_file)
    {
        $this->img_file = $img_file;
    }
    public function Header() {
        // get the current page break margin
        $bMargin = $this->getBreakMargin();
        // get current auto-page-break mode
        $auto_page_break = $this->AutoPageBreak;
        // disable auto-page-break
        $this->SetAutoPageBreak(false, 0);
        // margins Left, Top, Right, Bottom in pixels
        $this->Image($img_file, -9, -8, 316, 225, '', '', '', false, 300, '', false, false, 0);
        // restore auto-page-break status
        $this->SetAutoPageBreak($auto_page_break, $bMargin);
        // set the starting point for the page content
        $this->setPageMark();
    }
}
$MYPDF = new MYPDF($img_file);

Answer 2

Take a look at $GLOBALS variables here is a example

<?php
$a = 1;
$b = 2;

function Sum()
{
    $GLOBALS['b'] = $GLOBALS['a'] + $GLOBALS['b'];
} 

Sum();
echo $b;
?>

More on Variables scopes here

Answer 3

You need to make variable $img_file a global for use inside the function. This needs to be done inside the function Manual here: http://php.net/manual/en/language.variables.scope.php

public function Header() {
    global $img_file;
    // get the current page break margin
    $bMargin = $this->getBreakMargin();

    ...

Answer 4

This worked for me.

class MYPDF extends TCPDF {
  private $data = array();

  public function setData($key, $value) {
    $this->data[$key] = $value;
  }

  public function Header() {
    $this->data['invoice_no'];
    .... 
  }
}    
$pdf = new MYPDF(PDF_PAGE_ORIENTATION, PDF_UNIT, PDF_PAGE_FORMAT, true, 'UTF-8', false); 
$pdf->setData('invoice_no', $invoice_no);