math_cms/app/Services/OCR/ImageCropper.php

<?php

namespace App\Services\OCR;

use Intervention\Image\ImageManager;
use Intervention\Image\Drivers\Gd\Driver;

class ImageCropper
{
    protected ImageManager $manager;

    public function __construct()
    {
        $this->manager = new ImageManager(new Driver());
    }

    /**
     * Crop answer area from exam paper image
     * 
     * @param string $imagePath Full path to the image
     * @param array $coordinates ['x' => int, 'y' => int, 'width' => int, 'height' => int]
     * @return string Path to the cropped image
     */
    public function cropAnswerArea(string $imagePath, array $coordinates): string
    {
        $image = $this->manager->read($imagePath);
        
        // Get original dimensions
        $originalWidth = $image->width();
        $originalHeight = $image->height();
        
        // Default answer area: top-left corner (10% width, 15% height)
        $x = $coordinates['x'] ?? 0;
        $y = $coordinates['y'] ?? 0;
        $width = $coordinates['width'] ?? (int)($originalWidth * 0.1);
        $height = $coordinates['height'] ?? (int)($originalHeight * 0.15);
        
        // Crop the image
        $cropped = $image->crop($width, $height, $x, $y);
        
        // Save to temp directory
        $tempPath = storage_path('app/temp/answer_crops');
        if (!file_exists($tempPath)) {
            mkdir($tempPath, 0755, true);
        }
        
        $filename = 'answer_' . basename($imagePath);
        $outputPath = $tempPath . '/' . $filename;
        
        $cropped->save($outputPath);
        
        \Log::info('Cropped answer area', [
            'original' => $imagePath,
            'cropped' => $outputPath,
            'dimensions' => "{$width}x{$height} at ({$x},{$y})"
        ]);
        
        return $outputPath;
    }

    /**
     * Crop answer area from a specific question's top-left corner
     * 
     * @param string $imagePath Full path to the image
     * @param array $questionBbox Question's bounding box from Aliyun API
     * @return string Path to the cropped answer area
     */
    public function cropQuestionAnswerArea(string $imagePath, array $questionBbox): string
    {
        $image = $this->manager->read($imagePath);
        
        // Question bbox is typically: [{'x': int, 'y': int}, ...]
        // We need the top-left corner of the question area
        $minX = PHP_INT_MAX;
        $minY = PHP_INT_MAX;
        $maxX = 0;
        $maxY = 0;
        
        foreach ($questionBbox as $point) {
            $minX = min($minX, $point['x']);
            $minY = min($minY, $point['y']);
            $maxX = max($maxX, $point['x']);
            $maxY = max($maxY, $point['y']);
        }
        
        // Answer area: top-left corner of the question
        // Typically 10-15% of question width and height
        $questionWidth = $maxX - $minX;
        $questionHeight = $maxY - $minY;
        
        $answerWidth = (int)($questionWidth * 0.15);
        $answerHeight = (int)($questionHeight * 0.20);
        
        // Crop from top-left of question
        $cropped = $image->crop($answerWidth, $answerHeight, $minX, $minY);
        
        // Save to temp directory
        $tempPath = storage_path('app/temp/answer_crops');
        if (!file_exists($tempPath)) {
            mkdir($tempPath, 0755, true);
        }
        
        $filename = 'q_answer_' . uniqid() . '.jpg';
        $outputPath = $tempPath . '/' . $filename;
        
        $cropped->save($outputPath);
        
        return $outputPath;
    }

}