以类似 HTML 的方式计算列宽（基于单元格内容）

Question

我有一个数据网格，我想使用各种（而不是完美的）PHP 转换器/生成器将其导出为 RTF、PDF 等。

我最缺少的是HTML表格根据单元格中字符串的长度自动调整列宽（字符串包含换行符，这会使事情变得有点复杂，因为它们应该被保留）。

我需要一个算法，给定单元格的内容（纯文本）、表格的总宽度和字符的平均宽度，将返回每列的宽度。如果某些东西已经可用，我不想重新发明轮子。

当然，如果字体是可变宽度的，它就不可能是完美的，但近似值就可以了。或者它可能有一个可配置的表格，每个字符都有宽度。

任何提示将不胜感激。

Answer 1

这不是一件容易的事。

在PHPExcel中，当一个单元格设置为自动宽度时，我们使用gd库的imagettfbbox()函数

// font size should really be supplied in pixels in GD2,
// but since GD2 seems to assume 72dpi, pixels and points are the same
$fontFile = self::getTrueTypeFontFileFromFont($font);
$textBox = imagettfbbox($font->getSize(), $rotation, $fontFile, $text);

// Get corners positions
$lowerLeftCornerX  = $textBox[0];
$lowerLeftCornerY  = $textBox[1];
$lowerRightCornerX = $textBox[2];
$lowerRightCornerY = $textBox[3];
$upperRightCornerX = $textBox[4];
$upperRightCornerY = $textBox[5];
$upperLeftCornerX  = $textBox[6];
$upperLeftCornerY  = $textBox[7];

// Consider the rotation when calculating the width
$textWidth = max($lowerRightCornerX - $upperLeftCornerX, $upperRightCornerX - $lowerLeftCornerX);

return $textWidth;

但它非常密集，尤其是在处理大型工作表时，因此我们还有一种替代（近似）方法

// Calculate column width in pixels. We assume fixed glyph width. Result varies with font name and size.
switch ($fontName) {
    case 'Calibri':
        // value 8.26 was found via interpolation by inspecting real Excel files with Calibri 11 font.
        $columnWidth = (int) (8.26 * PHPExcel_Shared_String::CountCharacters($columnText));
        $columnWidth = $columnWidth * $fontSize / 11; // extrapolate from font size
        break;

    case 'Arial':
        // value 7 was found via interpolation by inspecting real Excel files with Arial 10 font.
        $columnWidth = (int) (7 * PHPExcel_Shared_String::CountCharacters($columnText));
        $columnWidth = $columnWidth * $fontSize / 10; // extrapolate from font size
        break;

    case 'Verdana':
        // value 8 was found via interpolation by inspecting real Excel files with Verdana 10 font.
        $columnWidth = (int) (8 * PHPExcel_Shared_String::CountCharacters($columnText));
        $columnWidth = $columnWidth * $fontSize / 10; // extrapolate from font size
        break;

    default:
        // just assume Calibri
        $columnWidth = (int) (8.26 * PHPExcel_Shared_String::CountCharacters($columnText));
        $columnWidth = $columnWidth * $fontSize / 11; // extrapolate from font size
        break;
}

// Calculate approximate rotated column width
if ($rotation !== 0) {
    if ($rotation == -165) {
        // stacked text
        $columnWidth = 4; // approximation
    } else {
        // rotated text
        $columnWidth = $columnWidth * cos(deg2rad($rotation))
                        + $fontSize * abs(sin(deg2rad($rotation))) / 5; // approximation
    }
}

// pixel width is an integer
$columnWidth = (int) $columnWidth;
return $columnWidth;