feat(multi-layout): implement form field copying and transformation for multi-page PDF to keep form data (#4314)

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Balázs Szücs 2025-09-25 22:26:11 +02:00 committed by GitHub
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@ -0,0 +1,658 @@
package stirling.software.common.util;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDDocumentCatalog;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDResources;
import org.apache.pdfbox.pdmodel.common.PDRectangle;
import org.apache.pdfbox.pdmodel.font.PDType1Font;
import org.apache.pdfbox.pdmodel.font.Standard14Fonts;
import org.apache.pdfbox.pdmodel.interactive.annotation.PDAnnotation;
import org.apache.pdfbox.pdmodel.interactive.annotation.PDAnnotationWidget;
import org.apache.pdfbox.pdmodel.interactive.form.*;
import lombok.extern.slf4j.Slf4j;
@Slf4j
public final class FormUtils {
private FormUtils() {}
public static boolean hasAnyRotatedPage(PDDocument document) {
try {
for (PDPage page : document.getPages()) {
int rot = page.getRotation();
int norm = ((rot % 360) + 360) % 360;
if (norm != 0) {
return true;
}
}
} catch (Exception e) {
log.warn("Failed to inspect page rotations: {}", e.getMessage(), e);
}
return false;
}
public static void copyAndTransformFormFields(
PDDocument sourceDocument,
PDDocument newDocument,
int totalPages,
int pagesPerSheet,
int cols,
int rows,
float cellWidth,
float cellHeight)
throws IOException {
PDDocumentCatalog sourceCatalog = sourceDocument.getDocumentCatalog();
PDAcroForm sourceAcroForm = sourceCatalog.getAcroForm();
if (sourceAcroForm == null || sourceAcroForm.getFields().isEmpty()) {
return;
}
PDDocumentCatalog newCatalog = newDocument.getDocumentCatalog();
PDAcroForm newAcroForm = new PDAcroForm(newDocument);
newCatalog.setAcroForm(newAcroForm);
PDResources dr = new PDResources();
PDType1Font helvetica = new PDType1Font(Standard14Fonts.FontName.HELVETICA);
PDType1Font zapfDingbats = new PDType1Font(Standard14Fonts.FontName.ZAPF_DINGBATS);
dr.put(COSName.getPDFName("Helv"), helvetica);
dr.put(COSName.getPDFName("ZaDb"), zapfDingbats);
newAcroForm.setDefaultResources(dr);
newAcroForm.setDefaultAppearance("/Helv 12 Tf 0 g");
// Do not mutate the source AcroForm; skip bad widgets during copy
newAcroForm.setNeedAppearances(true);
Map<String, Integer> fieldNameCounters = new HashMap<>();
// Build widget -> field map once for efficient lookups
Map<PDAnnotationWidget, PDField> widgetFieldMap = buildWidgetFieldMap(sourceAcroForm);
for (int pageIndex = 0; pageIndex < totalPages; pageIndex++) {
PDPage sourcePage = sourceDocument.getPage(pageIndex);
List<PDAnnotation> annotations = sourcePage.getAnnotations();
if (annotations.isEmpty()) {
continue;
}
int destinationPageIndex = pageIndex / pagesPerSheet;
int adjustedPageIndex = pageIndex % pagesPerSheet;
int rowIndex = adjustedPageIndex / cols;
int colIndex = adjustedPageIndex % cols;
if (destinationPageIndex >= newDocument.getNumberOfPages()) {
continue;
}
PDPage destinationPage = newDocument.getPage(destinationPageIndex);
PDRectangle sourceRect = sourcePage.getMediaBox();
float scaleWidth = cellWidth / sourceRect.getWidth();
float scaleHeight = cellHeight / sourceRect.getHeight();
float scale = Math.min(scaleWidth, scaleHeight);
float x = colIndex * cellWidth + (cellWidth - sourceRect.getWidth() * scale) / 2;
float y =
destinationPage.getMediaBox().getHeight()
- ((rowIndex + 1) * cellHeight
- (cellHeight - sourceRect.getHeight() * scale) / 2);
copyBasicFormFields(
sourceAcroForm,
newAcroForm,
sourcePage,
destinationPage,
x,
y,
scale,
pageIndex,
fieldNameCounters,
widgetFieldMap);
}
// Refresh appearances to ensure widgets render correctly across viewers
try {
// Use reflection to avoid compile-time dependency on PDFBox version
Method m = newAcroForm.getClass().getMethod("refreshAppearances");
m.invoke(newAcroForm);
} catch (NoSuchMethodException nsme) {
log.warn(
"AcroForm.refreshAppearances() not available in this PDFBox version; relying on NeedAppearances.");
} catch (Throwable t) {
log.warn("Failed to refresh field appearances via AcroForm: {}", t.getMessage(), t);
}
}
private static void copyBasicFormFields(
PDAcroForm sourceAcroForm,
PDAcroForm newAcroForm,
PDPage sourcePage,
PDPage destinationPage,
float offsetX,
float offsetY,
float scale,
int pageIndex,
Map<String, Integer> fieldNameCounters,
Map<PDAnnotationWidget, PDField> widgetFieldMap) {
try {
List<PDAnnotation> sourceAnnotations = sourcePage.getAnnotations();
List<PDAnnotation> destinationAnnotations = destinationPage.getAnnotations();
for (PDAnnotation annotation : sourceAnnotations) {
if (annotation instanceof PDAnnotationWidget widgetAnnotation) {
if (widgetAnnotation.getRectangle() == null) {
continue;
}
PDField sourceField =
widgetFieldMap != null ? widgetFieldMap.get(widgetAnnotation) : null;
if (sourceField == null) {
continue; // skip widgets without a matching field
}
if (sourceField instanceof PDTextField pdtextfield) {
createSimpleTextField(
newAcroForm,
destinationPage,
destinationAnnotations,
pdtextfield,
widgetAnnotation,
offsetX,
offsetY,
scale,
pageIndex,
fieldNameCounters);
} else if (sourceField instanceof PDCheckBox pdCheckBox) {
createSimpleCheckBoxField(
newAcroForm,
destinationPage,
destinationAnnotations,
pdCheckBox,
widgetAnnotation,
offsetX,
offsetY,
scale,
pageIndex,
fieldNameCounters);
} else if (sourceField instanceof PDRadioButton pdRadioButton) {
createSimpleRadioButtonField(
newAcroForm,
destinationPage,
destinationAnnotations,
pdRadioButton,
widgetAnnotation,
offsetX,
offsetY,
scale,
pageIndex,
fieldNameCounters);
} else if (sourceField instanceof PDComboBox pdComboBox) {
createSimpleComboBoxField(
newAcroForm,
destinationPage,
destinationAnnotations,
pdComboBox,
widgetAnnotation,
offsetX,
offsetY,
scale,
pageIndex,
fieldNameCounters);
} else if (sourceField instanceof PDListBox pdlistbox) {
createSimpleListBoxField(
newAcroForm,
destinationPage,
destinationAnnotations,
pdlistbox,
widgetAnnotation,
offsetX,
offsetY,
scale,
pageIndex,
fieldNameCounters);
} else if (sourceField instanceof PDSignatureField pdSignatureField) {
createSimpleSignatureField(
newAcroForm,
destinationPage,
destinationAnnotations,
pdSignatureField,
widgetAnnotation,
offsetX,
offsetY,
scale,
pageIndex,
fieldNameCounters);
} else if (sourceField instanceof PDPushButton pdPushButton) {
createSimplePushButtonField(
newAcroForm,
destinationPage,
destinationAnnotations,
pdPushButton,
widgetAnnotation,
offsetX,
offsetY,
scale,
pageIndex,
fieldNameCounters);
}
}
}
} catch (Exception e) {
log.warn(
"Failed to copy basic form fields for page {}: {}",
pageIndex,
e.getMessage(),
e);
}
}
private static void createSimpleTextField(
PDAcroForm newAcroForm,
PDPage destinationPage,
List<PDAnnotation> destinationAnnotations,
PDTextField sourceField,
PDAnnotationWidget sourceWidget,
float offsetX,
float offsetY,
float scale,
int pageIndex,
Map<String, Integer> fieldNameCounters) {
try {
PDTextField newTextField = new PDTextField(newAcroForm);
newTextField.setDefaultAppearance("/Helv 12 Tf 0 g");
boolean initialized =
initializeFieldWithWidget(
newAcroForm,
destinationPage,
destinationAnnotations,
newTextField,
sourceField.getPartialName(),
"textField",
sourceWidget,
offsetX,
offsetY,
scale,
pageIndex,
fieldNameCounters);
if (!initialized) {
return;
}
if (sourceField.getValueAsString() != null) {
newTextField.setValue(sourceField.getValueAsString());
}
} catch (Exception e) {
log.warn(
"Failed to create text field '{}': {}",
sourceField.getPartialName(),
e.getMessage(),
e);
}
}
private static void createSimpleCheckBoxField(
PDAcroForm newAcroForm,
PDPage destinationPage,
List<PDAnnotation> destinationAnnotations,
PDCheckBox sourceField,
PDAnnotationWidget sourceWidget,
float offsetX,
float offsetY,
float scale,
int pageIndex,
Map<String, Integer> fieldNameCounters) {
try {
PDCheckBox newCheckBox = new PDCheckBox(newAcroForm);
boolean initialized =
initializeFieldWithWidget(
newAcroForm,
destinationPage,
destinationAnnotations,
newCheckBox,
sourceField.getPartialName(),
"checkBox",
sourceWidget,
offsetX,
offsetY,
scale,
pageIndex,
fieldNameCounters);
if (!initialized) {
return;
}
if (sourceField.isChecked()) {
newCheckBox.check();
} else {
newCheckBox.unCheck();
}
} catch (Exception e) {
log.warn(
"Failed to create checkbox field '{}': {}",
sourceField.getPartialName(),
e.getMessage(),
e);
}
}
private static void createSimpleRadioButtonField(
PDAcroForm newAcroForm,
PDPage destinationPage,
List<PDAnnotation> destinationAnnotations,
PDRadioButton sourceField,
PDAnnotationWidget sourceWidget,
float offsetX,
float offsetY,
float scale,
int pageIndex,
Map<String, Integer> fieldNameCounters) {
try {
PDRadioButton newRadioButton = new PDRadioButton(newAcroForm);
boolean initialized =
initializeFieldWithWidget(
newAcroForm,
destinationPage,
destinationAnnotations,
newRadioButton,
sourceField.getPartialName(),
"radioButton",
sourceWidget,
offsetX,
offsetY,
scale,
pageIndex,
fieldNameCounters);
if (!initialized) {
return;
}
if (sourceField.getExportValues() != null) {
newRadioButton.setExportValues(sourceField.getExportValues());
}
if (sourceField.getValue() != null) {
newRadioButton.setValue(sourceField.getValue());
}
} catch (Exception e) {
log.warn(
"Failed to create radio button field '{}': {}",
sourceField.getPartialName(),
e.getMessage(),
e);
}
}
private static void createSimpleComboBoxField(
PDAcroForm newAcroForm,
PDPage destinationPage,
List<PDAnnotation> destinationAnnotations,
PDComboBox sourceField,
PDAnnotationWidget sourceWidget,
float offsetX,
float offsetY,
float scale,
int pageIndex,
Map<String, Integer> fieldNameCounters) {
try {
PDComboBox newComboBox = new PDComboBox(newAcroForm);
boolean initialized =
initializeFieldWithWidget(
newAcroForm,
destinationPage,
destinationAnnotations,
newComboBox,
sourceField.getPartialName(),
"comboBox",
sourceWidget,
offsetX,
offsetY,
scale,
pageIndex,
fieldNameCounters);
if (!initialized) {
return;
}
if (sourceField.getOptions() != null) {
newComboBox.setOptions(sourceField.getOptions());
}
if (sourceField.getValue() != null && !sourceField.getValue().isEmpty()) {
newComboBox.setValue(sourceField.getValue());
}
} catch (Exception e) {
log.warn(
"Failed to create combo box field '{}': {}",
sourceField.getPartialName(),
e.getMessage(),
e);
}
}
private static void createSimpleListBoxField(
PDAcroForm newAcroForm,
PDPage destinationPage,
List<PDAnnotation> destinationAnnotations,
PDListBox sourceField,
PDAnnotationWidget sourceWidget,
float offsetX,
float offsetY,
float scale,
int pageIndex,
Map<String, Integer> fieldNameCounters) {
try {
PDListBox newListBox = new PDListBox(newAcroForm);
boolean initialized =
initializeFieldWithWidget(
newAcroForm,
destinationPage,
destinationAnnotations,
newListBox,
sourceField.getPartialName(),
"listBox",
sourceWidget,
offsetX,
offsetY,
scale,
pageIndex,
fieldNameCounters);
if (!initialized) {
return;
}
if (sourceField.getOptions() != null) {
newListBox.setOptions(sourceField.getOptions());
}
if (sourceField.getValue() != null && !sourceField.getValue().isEmpty()) {
newListBox.setValue(sourceField.getValue());
}
} catch (Exception e) {
log.warn(
"Failed to create list box field '{}': {}",
sourceField.getPartialName(),
e.getMessage(),
e);
}
}
private static void createSimpleSignatureField(
PDAcroForm newAcroForm,
PDPage destinationPage,
List<PDAnnotation> destinationAnnotations,
PDSignatureField sourceField,
PDAnnotationWidget sourceWidget,
float offsetX,
float offsetY,
float scale,
int pageIndex,
Map<String, Integer> fieldNameCounters) {
try {
PDSignatureField newSignatureField = new PDSignatureField(newAcroForm);
boolean initialized =
initializeFieldWithWidget(
newAcroForm,
destinationPage,
destinationAnnotations,
newSignatureField,
sourceField.getPartialName(),
"signature",
sourceWidget,
offsetX,
offsetY,
scale,
pageIndex,
fieldNameCounters);
if (!initialized) {
return;
}
} catch (Exception e) {
log.warn(
"Failed to create signature field '{}': {}",
sourceField.getPartialName(),
e.getMessage(),
e);
}
}
private static void createSimplePushButtonField(
PDAcroForm newAcroForm,
PDPage destinationPage,
List<PDAnnotation> destinationAnnotations,
PDPushButton sourceField,
PDAnnotationWidget sourceWidget,
float offsetX,
float offsetY,
float scale,
int pageIndex,
Map<String, Integer> fieldNameCounters) {
try {
PDPushButton newPushButton = new PDPushButton(newAcroForm);
boolean initialized =
initializeFieldWithWidget(
newAcroForm,
destinationPage,
destinationAnnotations,
newPushButton,
sourceField.getPartialName(),
"pushButton",
sourceWidget,
offsetX,
offsetY,
scale,
pageIndex,
fieldNameCounters);
} catch (Exception e) {
log.warn(
"Failed to create push button field '{}': {}",
sourceField.getPartialName(),
e.getMessage(),
e);
}
}
private static <T extends PDTerminalField> boolean initializeFieldWithWidget(
PDAcroForm newAcroForm,
PDPage destinationPage,
List<PDAnnotation> destinationAnnotations,
T newField,
String originalName,
String fallbackName,
PDAnnotationWidget sourceWidget,
float offsetX,
float offsetY,
float scale,
int pageIndex,
Map<String, Integer> fieldNameCounters) {
String baseName = (originalName != null) ? originalName : fallbackName;
String newFieldName = generateUniqueFieldName(baseName, pageIndex, fieldNameCounters);
newField.setPartialName(newFieldName);
PDAnnotationWidget newWidget = new PDAnnotationWidget();
PDRectangle sourceRect = sourceWidget.getRectangle();
if (sourceRect == null) {
return false;
}
float newX = (sourceRect.getLowerLeftX() * scale) + offsetX;
float newY = (sourceRect.getLowerLeftY() * scale) + offsetY;
float newWidth = sourceRect.getWidth() * scale;
float newHeight = sourceRect.getHeight() * scale;
newWidget.setRectangle(new PDRectangle(newX, newY, newWidth, newHeight));
newWidget.setPage(destinationPage);
newField.getWidgets().add(newWidget);
newWidget.setParent(newField);
newAcroForm.getFields().add(newField);
destinationAnnotations.add(newWidget);
return true;
}
private static String generateUniqueFieldName(
String originalName, int pageIndex, Map<String, Integer> fieldNameCounters) {
String baseName = "page" + pageIndex + "_" + originalName;
Integer counter = fieldNameCounters.get(baseName);
if (counter == null) {
counter = 0;
} else {
counter++;
}
fieldNameCounters.put(baseName, counter);
return counter == 0 ? baseName : baseName + "_" + counter;
}
private static Map<PDAnnotationWidget, PDField> buildWidgetFieldMap(PDAcroForm acroForm) {
Map<PDAnnotationWidget, PDField> map = new HashMap<>();
if (acroForm == null) {
return map;
}
try {
for (PDField field : acroForm.getFieldTree()) {
List<PDAnnotationWidget> widgets = field.getWidgets();
if (widgets != null) {
for (PDAnnotationWidget w : widgets) {
if (w != null) {
map.put(w, field);
}
}
}
}
} catch (Exception e) {
log.warn("Failed to build widget->field map: {}", e.getMessage(), e);
}
return map;
}
}

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@ -1,6 +1,6 @@
package stirling.software.SPDF.controller.api;
import java.awt.*;
import java.awt.Color;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
@ -24,15 +24,18 @@ import io.swagger.v3.oas.annotations.Operation;
import io.swagger.v3.oas.annotations.tags.Tag;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import stirling.software.SPDF.model.api.general.MergeMultiplePagesRequest;
import stirling.software.common.service.CustomPDFDocumentFactory;
import stirling.software.common.util.FormUtils;
import stirling.software.common.util.WebResponseUtils;
@RestController
@RequestMapping("/api/v1/general")
@Tag(name = "General", description = "General APIs")
@RequiredArgsConstructor
@Slf4j
public class MultiPageLayoutController {
private final CustomPDFDocumentFactory pdfDocumentFactory;
@ -103,7 +106,8 @@ public class MultiPageLayoutController {
float scale = Math.min(scaleWidth, scaleHeight);
int adjustedPageIndex =
i % pagesPerSheet; // This will reset the index for every new page
i % pagesPerSheet; // Close the current content stream and create a new
// page and content stream
int rowIndex = adjustedPageIndex / cols;
int colIndex = adjustedPageIndex % cols;
@ -131,7 +135,28 @@ public class MultiPageLayoutController {
}
}
contentStream.close(); // Close the final content stream
contentStream.close();
// If any source page is rotated, skip form copying/transformation entirely
boolean hasRotation = FormUtils.hasAnyRotatedPage(sourceDocument);
if (hasRotation) {
log.info("Source document has rotated pages; skipping form field copying.");
} else {
try {
FormUtils.copyAndTransformFormFields(
sourceDocument,
newDocument,
totalPages,
pagesPerSheet,
cols,
rows,
cellWidth,
cellHeight);
} catch (Exception e) {
log.warn("Failed to copy and transform form fields: {}", e.getMessage(), e);
}
}
sourceDocument.close();
ByteArrayOutputStream baos = new ByteArrayOutputStream();

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@ -0,0 +1,116 @@
package stirling.software.SPDF.controller.api;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.junit.jupiter.MockitoExtension;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.mock.web.MockMultipartFile;
import stirling.software.SPDF.model.api.general.MergeMultiplePagesRequest;
import stirling.software.common.service.CustomPDFDocumentFactory;
@ExtendWith(MockitoExtension.class)
class MultiPageLayoutControllerTest {
@Mock private CustomPDFDocumentFactory pdfDocumentFactory;
@InjectMocks private MultiPageLayoutController controller;
private MockMultipartFile fileWithExt;
private MockMultipartFile fileNoExt;
@BeforeEach
void setup() {
fileWithExt =
new MockMultipartFile(
"fileInput", "test.pdf", "application/pdf", new byte[] {1, 2, 3});
fileNoExt =
new MockMultipartFile("fileInput", "name", "application/pdf", new byte[] {4, 5, 6});
}
@Test
@DisplayName("Rejects non-2/3 and non-perfect-square pagesPerSheet")
void invalidPagesPerSheetThrows() {
MergeMultiplePagesRequest req = new MergeMultiplePagesRequest();
req.setPagesPerSheet(5);
req.setAddBorder(Boolean.TRUE);
req.setFileInput(fileWithExt);
Assertions.assertThrows(
IllegalArgumentException.class, () -> controller.mergeMultiplePagesIntoOne(req));
}
@Test
@DisplayName("Generates PDF and filename suffix for perfect-square layout with no source pages")
void perfectSquareNoPages() throws Exception {
PDDocument source = new PDDocument();
PDDocument target = new PDDocument();
Mockito.when(pdfDocumentFactory.load(fileWithExt)).thenReturn(source);
Mockito.when(pdfDocumentFactory.createNewDocumentBasedOnOldDocument(source))
.thenReturn(target);
MergeMultiplePagesRequest req = new MergeMultiplePagesRequest();
req.setPagesPerSheet(4);
req.setAddBorder(Boolean.FALSE);
req.setFileInput(fileWithExt);
ResponseEntity<byte[]> resp = controller.mergeMultiplePagesIntoOne(req);
Assertions.assertEquals(HttpStatus.OK, resp.getStatusCode());
Assertions.assertEquals(MediaType.APPLICATION_PDF, resp.getHeaders().getContentType());
Assertions.assertNotNull(resp.getBody());
Assertions.assertTrue(resp.getBody().length > 0);
Assertions.assertEquals(
"test_layoutChanged.pdf", resp.getHeaders().getContentDisposition().getFilename());
}
@Test
@DisplayName("Merges single source page into 2-up layout and returns PDF")
void twoUpWithSinglePage() throws Exception {
PDDocument source = new PDDocument();
source.addPage(new PDPage());
PDDocument target = new PDDocument();
Mockito.when(pdfDocumentFactory.load(fileWithExt)).thenReturn(source);
Mockito.when(pdfDocumentFactory.createNewDocumentBasedOnOldDocument(source))
.thenReturn(target);
MergeMultiplePagesRequest req = new MergeMultiplePagesRequest();
req.setPagesPerSheet(2);
req.setAddBorder(Boolean.TRUE);
req.setFileInput(fileWithExt);
ResponseEntity<byte[]> resp = controller.mergeMultiplePagesIntoOne(req);
Assertions.assertEquals(HttpStatus.OK, resp.getStatusCode());
Assertions.assertEquals(MediaType.APPLICATION_PDF, resp.getHeaders().getContentType());
Assertions.assertNotNull(resp.getBody());
Assertions.assertTrue(resp.getBody().length > 0);
}
@Test
@DisplayName("Uses input name without extension and appends suffix for 3-up")
void threeUpWithNameNoExtension() throws Exception {
PDDocument source = new PDDocument();
PDDocument target = new PDDocument();
Mockito.when(pdfDocumentFactory.load(fileNoExt)).thenReturn(source);
Mockito.when(pdfDocumentFactory.createNewDocumentBasedOnOldDocument(source))
.thenReturn(target);
MergeMultiplePagesRequest req = new MergeMultiplePagesRequest();
req.setPagesPerSheet(3);
req.setAddBorder(Boolean.TRUE);
req.setFileInput(fileNoExt);
ResponseEntity<byte[]> resp = controller.mergeMultiplePagesIntoOne(req);
Assertions.assertEquals(
"name_layoutChanged.pdf", resp.getHeaders().getContentDisposition().getFilename());
}
}