Copy pages with the form fields of their widgets

BUILD.gn

@@ -237,6 +237,8 @@ source_set("pdfium_public_headers_impl") {
     "public/epdf_pieceinfo.h",
     # EmbedPDF: PNG encoding of RGBA bitmaps.
     "public/epdf_png.h",
+    # EmbedPDF: what we add to public/fpdf_ppo.h.
+    "public/epdf_ppo.h",
     # EmbedPDF: what we add to public/fpdf_progressive.h.
     "public/epdf_progressive.h",
     # EmbedPDF: typed measurement, viewport and caption API.

core/fpdfapi/edit/cpdf_pageorganizer.cpp

@@ -126,6 +126,11 @@ bool CPDF_PageOrganizer::UpdateReference(RetainPtr<CPDF_Object> obj) {
   }
 }
 
+// EmbedPDF(epdf-api): see the header.
+bool CPDF_PageOrganizer::RetargetReferences(RetainPtr<CPDF_Object> obj) {
+  return UpdateReference(std::move(obj));
+}
+
 uint32_t CPDF_PageOrganizer::GetNewObjId(CPDF_Reference* ref) {
   if (!ref) {
     return 0;

core/fpdfapi/edit/cpdf_pageorganizer.h

@@ -21,6 +21,19 @@ class CPDF_Object;
 class CPDF_Reference;
 
 class CPDF_PageOrganizer {
+ public:
+  // EmbedPDF(epdf-api): EPDFDoc_ImportPages() (fpdfsdk/epdf_ppo.cpp) copies
+  // the form fields above the copied widgets: it names its copies before the
+  // pages are copied, finds the copies the pages made, and points the
+  // references in its own copies at the destination.
+  void MapObjectNumber(uint32_t src_obj_num, uint32_t dest_obj_num) {
+    AddObjectMapping(src_obj_num, dest_obj_num);
+  }
+  const std::map<uint32_t, uint32_t>& object_number_map() const {
+    return object_number_map_;
+  }
+  bool RetargetReferences(RetainPtr<CPDF_Object> obj);
+
  protected:
   CPDF_PageOrganizer(CPDF_Document* dest_doc, CPDF_Document* src_doc);
   ~CPDF_PageOrganizer();

fpdfsdk/BUILD.gn

@@ -75,6 +75,8 @@ source_set("fpdfsdk") {
     # EmbedPDF: what a parsed page costs, and whether it is still current.
     "epdf_page_residency.cpp",
     "epdf_png_shim.cpp",
+    # EmbedPDF: pages copied with their form fields (public/epdf_ppo.h).
+    "epdf_ppo.cpp",
     "epdf_redact.cpp",
     "epdf_threading.cpp",
     "epdf_wrapped_appearance.cpp",
@@ -274,6 +276,8 @@ pdfium_embeddertest_source_set("embeddertests") {
     "epdf_sliced_load_embeddertest.cpp",
     # EmbedPDF: covers the /Names /Pages and /Templates name-tree APIs.
     "epdf_named_pages_embeddertest.cpp",
+    # EmbedPDF: covers pages copied with their form fields (public/epdf_ppo.h).
+    "epdf_ppo_embeddertest.cpp",
     # EmbedPDF: a content rewrite keeps what it did not change.
     "epdf_content_rewrite_embeddertest.cpp",
     "epdf_redact_embeddertest.cpp",

fpdfsdk/epdf_c_api_test.c

@@ -27,6 +27,7 @@
 #include "public/epdf_outline.h"
 #include "public/epdf_pieceinfo.h"
 #include "public/epdf_png.h"
+#include "public/epdf_ppo.h"
 #include "public/epdf_progressive.h"
 #include "public/epdf_redact.h"
 #include "public/epdf_save.h"
@@ -329,6 +330,7 @@ int CheckEmbedPDFCApi(void) {
   CHK(EPDFForm_GetFieldOptionLabel);
   CHK(EPDFForm_GetFieldOptionValue);
   CHK(EPDFForm_GetFieldOrigin);
+  CHK(EPDFForm_GetFieldPartialName);
   CHK(EPDFForm_GetFieldTopIndex);
   CHK(EPDFForm_GetFieldValueAt);
   CHK(EPDFForm_GetFieldValueKind);
@@ -502,6 +504,10 @@ int CheckEmbedPDFCApi(void) {
   // epdf_png.h
   CHK(EPDF_PNG_EncodeRGBA);
 
+  // epdf_ppo.h
+  CHK(EPDFDoc_GetImportFieldRoots);
+  CHK(EPDFDoc_ImportPages);
+
   // epdf_progressive.h
   CHK(EPDF_RenderPageBitmapWithMatrix_Start);
   CHK(EPDF_RenderPage_Continue);

fpdfsdk/epdf_form.cpp

@@ -2973,6 +2973,22 @@ EPDFForm_SetFieldName(FPDF_DOCUMENT document,
   return true;
 }
 
+FPDF_EXPORT unsigned long FPDF_CALLCONV
+EPDFForm_GetFieldPartialName(FPDF_DOCUMENT document,
+                             uint32_t field_objnum,
+                             FPDF_WCHAR* buffer,
+                             unsigned long buflen) {
+  ScopedFPDFDocumentView document_view(document);
+  RetainPtr<const CPDF_Dictionary> field =
+      ResolveFieldDict(document_view.Get(), field_objnum);
+  if (!field || !field->KeyExist(pdfium::form_fields::kT)) {
+    return 0;
+  }
+  return Utf16EncodeMaybeCopyAndReturnLength(
+      field->GetUnicodeTextFor(pdfium::form_fields::kT),
+      UNSAFE_BUFFERS(SpanFromFPDFApiArgs(buffer, buflen)));
+}
+
 FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV
 EPDFForm_SetFieldFlags(FPDF_DOCUMENT document,
                        uint32_t field_objnum,