Add a callback function: PDFiumEngine::Form_PageEvent

pdf/pdfium/pdfium_engine.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PDF_PDFIUM_PDFIUM_ENGINE_H_
 #define PDF_PDFIUM_PDFIUM_ENGINE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 518 matching lines @@
                                       FPDF_DOCUMENT document);
   static void Form_GetPageViewRect(FPDF_FORMFILLINFO* param,
                                    FPDF_PAGE page,
                                    double* left,
                                    double* top,
                                    double* right,
                                    double* bottom);
   static int Form_GetPlatform(FPDF_FORMFILLINFO* param,
                               void* platform,
                               int length);
+  static void Form_PageEvent(FPDF_FORMFILLINFO* param,
+                             int iPageIndex,
+                             int iEventType);
   static FPDF_BOOL Form_PopupMenu(FPDF_FORMFILLINFO* param,
                                   FPDF_PAGE page,
                                   FPDF_WIDGET widget,
                                   int menu_flag,
                                   float x,
                                   float y);
   static FPDF_BOOL Form_PostRequestURL(FPDF_FORMFILLINFO* param,
                                        FPDF_WIDESTRING url,
                                        FPDF_WIDESTRING data,
                                        FPDF_WIDESTRING content_type,
@@ skipping 199 matching lines @@
   bool GetPDFPageSizeByIndex(const void* pdf_buffer,
                              int pdf_buffer_size,
                              int page_number,
                              double* width,
                              double* height) override;
 };
 
 }  // namespace chrome_pdf
 
 #endif  // PDF_PDFIUM_PDFIUM_ENGINE_H_