为什么此代码无法使用PHP Zend_Pdf库在PDF上居中显示文本? [英] Why is this code to center text on a PDF using the PHP Zend_Pdf Library not working?

问题描述

我正在尝试在服务器上动态创建PDF文档，并使用Zend_Pdf库将其发送给客户端. PDF上的所有文本都必须与页面居中对齐，页面大小应为字母大小，横向.使用我在各种站点上多次发现的功能时，我遇到了一个问题-中心对齐不正确.所有文本都显示在左侧太远的位置.这是我的代码:

I'm attempting to dynamically create PDF documents on the server and send them to the client using the Zend_Pdf library. All text on the PDF needs to be center aligned to the page, which will be letter-sized, landscape. Using functions that I have found multiple times on various sites, I'm having a problem - the center justification is off. All text is appearing way too far to the left. Here is my code:

<?
require('Zend/Pdf.php');

$font = Zend_Pdf_Font::fontWithName(Zend_Pdf_Font::FONT_HELVETICA);
$pdf = new Zend_Pdf();

// Create a new page, add to page listing
$pdfPage = $pdf->newPage(Zend_Pdf_Page::SIZE_LETTER_LANDSCAPE);
$pdf->pages[] = $pdfPage;

// Add certify that
$pdfPage->setFont($font, 15.75);
drawCenteredText($pdfPage, "THIS IS TO CERTIFY THAT", 378);

// Add name
$pdfPage->setFont($font, 39.75);
drawCenteredText($pdfPage, "Example Name", 314.25);

// Headers
header("Content-type: application/pdf");
header("Content-Disposition: inline; filename=\"cert.pdf\"");
header('Content-Transfer-Encoding: binary');
header('Accept-Ranges: bytes');

// Output PDF
echo $pdf->render();


function drawCenteredText($page, $text, $bottom) {  
    $text_width = getTextWidth($text, $page->getFont(), $page->getFontSize());
    $box_width = $page->getWidth();
    $left = ($box_width - $text_width) / 2;

    $page->drawText($text, $left, $bottom, 'UTF-8');
}

function getTextWidth($text, $font, $font_size) {
    $drawing_text = iconv('', 'UTF-8', $text);
    $characters    = array();
    for ($i = 0; $i < strlen($drawing_text); $i++) {
        $characters[] = (ord($drawing_text[$i++]) << 8) | ord ($drawing_text[$i]);
    }
    $glyphs        = $font->glyphNumbersForCharacters($characters);
    $widths        = $font->widthsForGlyphs($glyphs);
    $text_width   = (array_sum($widths) / $font->getUnitsPerEm()) * $font_size;
    return $text_width;
}

?>

...这就是结果.

推荐答案

万一其他人遇到类似问题，问题就在这里:

In case anyone else runs into a similar problem, the issue is here:

function getTextWidth($text, $font, $font_size) {
    $drawing_text = iconv('', 'UTF-8', $text);
    $characters    = array();
    for ($i = 0; $i < strlen($drawing_text); $i++) {
        $characters[] = (ord($drawing_text[$i++]) << 8) | ord ($drawing_text[$i]);
    }
    $glyphs        = $font->glyphNumbersForCharacters($characters);
    $widths        = $font->widthsForGlyphs($glyphs);
    $text_width   = (array_sum($widths) / $font->getUnitsPerEm()) * $font_size;
    return $text_width;
}

在构建字符数组时，字符加载不正确-8位而不是16位.

When building the characters array, the characters are being loaded incorrectly - 8 bits, not 16.

$characters[] = ord ($drawing_text[$i]);

这可以解决问题，并正确计算文本宽度.

This solves the problem, and correctly calculates text width.

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