Stirling-PDF/src/main/java/stirling/software/SPDF/controller/api/ScalePagesController.java

package stirling.software.SPDF.controller.api;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import org.apache.pdfbox.multipdf.LayerUtility;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDPageContentStream;
import org.apache.pdfbox.pdmodel.common.PDRectangle;
import org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject;
import org.apache.pdfbox.util.Matrix;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import io.swagger.v3.oas.annotations.Operation;
import io.swagger.v3.oas.annotations.tags.Tag;
import stirling.software.SPDF.model.api.general.ScalePagesRequest;
import stirling.software.SPDF.utils.WebResponseUtils;
@RestController
@RequestMapping("/api/v1/general")
@Tag(name = "General", description = "General APIs")
public class ScalePagesController {

	private static final Logger logger = LoggerFactory.getLogger(ScalePagesController.class);

	@PostMapping(value = "/scale-pages", consumes = "multipart/form-data")
	@Operation(summary = "Change the size of a PDF page/document", description = "This operation takes an input PDF file and the size to scale the pages to in the output PDF file. Input:PDF Output:PDF Type:SISO")
	public ResponseEntity<byte[]> scalePages(@ModelAttribute ScalePagesRequest request) throws IOException {
	    MultipartFile file = request.getFileInput();
	    String targetPDRectangle = request.getPageSize();
	    float scaleFactor = request.getScaleFactor();

		Map<String, PDRectangle> sizeMap = new HashMap<>();
		// Add A0 - A10
		sizeMap.put("A0", PDRectangle.A0);
		sizeMap.put("A1", PDRectangle.A1);
		sizeMap.put("A2", PDRectangle.A2);
		sizeMap.put("A3", PDRectangle.A3);
		sizeMap.put("A4", PDRectangle.A4);
		sizeMap.put("A5", PDRectangle.A5);
		sizeMap.put("A6", PDRectangle.A6);

		// Add other sizes
		sizeMap.put("LETTER", PDRectangle.LETTER);
		sizeMap.put("LEGAL", PDRectangle.LEGAL);

		if (!sizeMap.containsKey(targetPDRectangle)) {
			throw new IllegalArgumentException(
					"Invalid PDRectangle. It must be one of the following: A0, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10");
		}

		PDRectangle targetSize = sizeMap.get(targetPDRectangle);

	    PDDocument sourceDocument = PDDocument.load(file.getBytes());
	    PDDocument outputDocument = new PDDocument();

	    int totalPages = sourceDocument.getNumberOfPages();
	    for (int i = 0; i < totalPages; i++) {
	        PDPage sourcePage = sourceDocument.getPage(i);
	        PDRectangle sourceSize = sourcePage.getMediaBox();
	        
	        float scaleWidth = targetSize.getWidth() / sourceSize.getWidth();
	        float scaleHeight = targetSize.getHeight() / sourceSize.getHeight();
	        float scale = Math.min(scaleWidth, scaleHeight) * scaleFactor;
	        
	        PDPage newPage = new PDPage(targetSize);
	        outputDocument.addPage(newPage);
	        
	        PDPageContentStream contentStream = new PDPageContentStream(outputDocument, newPage, PDPageContentStream.AppendMode.APPEND, true);
	        
	        float x = (targetSize.getWidth() - sourceSize.getWidth() * scale) / 2;
	        float y = (targetSize.getHeight() - sourceSize.getHeight() * scale) / 2;
	        
	        contentStream.saveGraphicsState();
	        contentStream.transform(Matrix.getTranslateInstance(x, y));
	        contentStream.transform(Matrix.getScaleInstance(scale, scale));
	        
	        LayerUtility layerUtility = new LayerUtility(outputDocument);
	        PDFormXObject form = layerUtility.importPageAsForm(sourceDocument, i);
	        contentStream.drawForm(form);

	        contentStream.restoreGraphicsState();
	        contentStream.close();
	    }





	    ByteArrayOutputStream baos = new ByteArrayOutputStream();
	    outputDocument.save(baos);
	    outputDocument.close();
	    sourceDocument.close();
	    
	    
		return WebResponseUtils.bytesToWebResponse(baos.toByteArray(),
				file.getOriginalFilename().replaceFirst("[.][^.]+$", "") + "_scaled.pdf");
	}


}