process_sheet/fastadmin/application/common/library/ps/PaperSize.php

<?php

namespace app\common\library\ps;

/**
 * 套打纸张尺寸。坐标用相对整张纸的百分比，毫米和像素用来核对原稿是否铺满纸面。
 */
class PaperSize
{
    /**
     * @return array name => [w_mm, h_mm, px_w@300dpi, px_h@300dpi]
     */
    public static function presets()
    {
        return [
            'A4' => [
                'label' => 'A4（210 × 297 mm）',
                'w'     => 210,
                'h'     => 297,
                'dpi'   => 300,
            ],
            'A5' => [
                'label' => 'A5（148 × 210 mm）',
                'w'     => 148,
                'h'     => 210,
                'dpi'   => 300,
            ],
            'custom' => [
                'label' => '自定义毫米',
                'w'     => 210,
                'h'     => 297,
                'dpi'   => 300,
            ],
        ];
    }

    /**
     * 300DPI 下的建议像素（整数）。
     * @param float $mmW
     * @param float $mmH
     * @param int   $dpi
     * @return array
     */
    public static function pixels($mmW, $mmH, $dpi = 300)
    {
        $dpi = $dpi > 0 ? (int)$dpi : 300;
        return [
            'w'   => (int)round($mmW / 25.4 * $dpi),
            'h'   => (int)round($mmH / 25.4 * $dpi),
            'dpi' => $dpi,
        ];
    }

    /**
     * @param string $name
     * @param float  $w
     * @param float  $h
     * @return array
     */
    public static function resolve($name, $w = 0, $h = 0)
    {
        $name = strtoupper(trim((string)$name));
        if ($name === 'CUSTOM' || $name === '自定义') {
            $name = 'custom';
        }
        $presets = self::presets();
        if ($name === 'A5') {
            $out = $presets['A5'];
            $out['name'] = 'A5';
        } elseif ($name === 'CUSTOM' || $name === 'custom') {
            $out = $presets['custom'];
            $out['name'] = 'custom';
            if ((float)$w > 0) {
                $out['w'] = (float)$w;
            }
            if ((float)$h > 0) {
                $out['h'] = (float)$h;
            }
        } else {
            $out = $presets['A4'];
            $out['name'] = 'A4';
        }
        if ($out['w'] <= 0 || $out['h'] <= 0) {
            $out['w'] = 210;
            $out['h'] = 297;
            $out['name'] = 'A4';
        }
        $px = self::pixels($out['w'], $out['h'], (int)$out['dpi']);
        $out['px_w'] = $px['w'];
        $out['px_h'] = $px['h'];
        return $out;
    }

    /**
     * 图片高宽比与纸张是否一致（扫描裁切允许少量偏差）。
     * @param int   $imgW
     * @param int   $imgH
     * @param float $mmW
     * @param float $mmH
     * @param float $tolerance
     * @return bool
     */
    public static function ratioMatches($imgW, $imgH, $mmW, $mmH, $tolerance = 0.04)
    {
        if ($imgW < 10 || $imgH < 10 || $mmW <= 0 || $mmH <= 0) {
            return false;
        }
        $imgRatio = $imgH / $imgW;
        $paperRatio = $mmH / $mmW;
        return abs($imgRatio - $paperRatio) / $paperRatio <= $tolerance;
    }

    /**
     * 按纸张毫米反推当前图的 DPI（取宽边）。
     * @param int   $imgW
     * @param float $mmW
     * @return int
     */
    public static function dpiOf($imgW, $mmW)
    {
        if ($imgW < 1 || $mmW <= 0) {
            return 0;
        }
        return (int)round($imgW / ($mmW / 25.4));
    }
}