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

package stirling.software.SPDF.controller.api;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpHeaders;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import com.itextpdf.kernel.geom.PageSize;
import com.itextpdf.kernel.geom.Rectangle;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfPage;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.kernel.pdf.canvas.PdfCanvas;
import com.itextpdf.kernel.pdf.xobject.PdfFormXObject;

import io.swagger.v3.oas.annotations.Operation;
import io.swagger.v3.oas.annotations.Parameter;
import io.swagger.v3.oas.annotations.media.Schema;
import stirling.software.SPDF.utils.WebResponseUtils;
import java.util.HashMap;
import java.util.Map;
@RestController
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.")
	public ResponseEntity<byte[]> scalePages(
	    @Parameter(description = "The input PDF file", required = true) @RequestParam("fileInput") MultipartFile file,
	    @Parameter(description = "The scale of pages in the output PDF. Acceptable values are A0-A10, B0-B9, LETTER, TABLOID, LEDGER, LEGAL, EXECUTIVE.", required = true, schema = @Schema(type = "String", allowableValues = { "A0", "A1", "A2", "A3", "A4", "A5", "A6", "A7", "A8", "A9", "A10", "B0", "B1", "B2", "B3", "B4", "B5", "B6", "B7", "B8", "B9", "LETTER", "TABLOID", "LEDGER", "LEGAL", "EXECUTIVE" })) @RequestParam("pageSize") String targetPageSize,
	    @Parameter(description = "The scale of the content on the pages of the output PDF. Acceptable values are floats.", required = true, schema = @Schema(type = "float")) @RequestParam("scaleFactor") float scaleFactor)
	    throws IOException {

		Map<String, PageSize> sizeMap = new HashMap<>();
	    // Add A0 - A10
	    sizeMap.put("A0", PageSize.A0);
	    sizeMap.put("A1", PageSize.A1);
	    sizeMap.put("A2", PageSize.A2);
	    sizeMap.put("A3", PageSize.A3);
	    sizeMap.put("A4", PageSize.A4);
	    sizeMap.put("A5", PageSize.A5);
	    sizeMap.put("A6", PageSize.A6);
	    sizeMap.put("A7", PageSize.A7);
	    sizeMap.put("A8", PageSize.A8);
	    sizeMap.put("A9", PageSize.A9);
	    sizeMap.put("A10", PageSize.A10);
	    // Add B0 - B9
	    sizeMap.put("B0", PageSize.B0);
	    sizeMap.put("B1", PageSize.B1);
	    sizeMap.put("B2", PageSize.B2);
	    sizeMap.put("B3", PageSize.B3);
	    sizeMap.put("B4", PageSize.B4);
	    sizeMap.put("B5", PageSize.B5);
	    sizeMap.put("B6", PageSize.B6);
	    sizeMap.put("B7", PageSize.B7);
	    sizeMap.put("B8", PageSize.B8);
	    sizeMap.put("B9", PageSize.B9);
	    // Add other sizes
	    sizeMap.put("LETTER", PageSize.LETTER);
	    sizeMap.put("TABLOID", PageSize.TABLOID);
	    sizeMap.put("LEDGER", PageSize.LEDGER);
	    sizeMap.put("LEGAL", PageSize.LEGAL);
	    sizeMap.put("EXECUTIVE", PageSize.EXECUTIVE);
	    
	    if (!sizeMap.containsKey(targetPageSize)) {
	        throw new IllegalArgumentException("Invalid pageSize. It must be one of the following: A0, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10");
	    }
		
		PageSize pageSize = sizeMap.get(targetPageSize);
		

		byte[] bytes = file.getBytes();
		PdfReader reader = new PdfReader(new ByteArrayInputStream(bytes));
		PdfDocument pdfDoc = new PdfDocument(reader);

		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		PdfWriter writer = new PdfWriter(baos);
		PdfDocument outputPdf = new PdfDocument(writer);
		
		
	    
		int totalPages = pdfDoc.getNumberOfPages();

		for (int i = 1; i <= totalPages; i++) {
			PdfPage page = outputPdf.addNewPage(pageSize);
			PdfCanvas pdfCanvas = new PdfCanvas(page);

			// Get the page and calculate scaling factors
			Rectangle rect = pdfDoc.getPage(i).getPageSize();
			float scaleWidth = pageSize.getWidth() / rect.getWidth();
			float scaleHeight = pageSize.getHeight() / rect.getHeight();
			float scale = Math.min(scaleWidth, scaleHeight) * scaleFactor;
            System.out.println("Scale: " + scale);

			PdfFormXObject formXObject = pdfDoc.getPage(i).copyAsFormXObject(outputPdf);
			float x = (pageSize.getWidth() - rect.getWidth() * scale) / 2; // Center Page
			float y = (pageSize.getHeight() - rect.getHeight() * scale) / 2;

			// Save the graphics state, apply the transformations, add the object, and then
			// restore the graphics state
			pdfCanvas.saveState();
			pdfCanvas.concatMatrix(scale, 0, 0, scale, x, y);
			pdfCanvas.addXObject(formXObject, 0, 0);
			pdfCanvas.restoreState();
		}

		outputPdf.close();
		byte[] pdfContent = baos.toByteArray();
		pdfDoc.close();
		return WebResponseUtils.bytesToWebResponse(pdfContent, file.getOriginalFilename().replaceFirst("[.][^.]+$", "") + "_scaled.pdf");
	}
}