PDF rotation should maintain current page.

pdf/pdfium/pdfium_engine.cc

 // 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.
 
 #include "pdf/pdfium/pdfium_engine.h"
 
 #include <math.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 839 matching lines @@
 void PDFiumEngine::AddSegment(FX_DOWNLOADHINTS* param,
                               size_t offset, size_t size) {
   PDFiumEngine::DownloadHints* download_hints =
       static_cast<PDFiumEngine::DownloadHints*>(param);
   return download_hints->loader->RequestData(offset, size);
 }
 
 bool PDFiumEngine::New(const char* url,
                        const char* headers) {
   url_ = url;
-  if (!headers)
+  if (headers)
+    headers_ = headers;
+  else
     headers_.clear();
-  else
-    headers_ = headers;
   return true;
 }
 
 void PDFiumEngine::PageOffsetUpdated(const pp::Point& page_offset) {
   page_offset_ = page_offset;
 }
 
 void PDFiumEngine::PluginSizeUpdated(const pp::Size& size) {
   CancelPaints();
 
@@ skipping 2280 matching lines @@
   DCHECK(valid_);
   return ++index_;
 }
 
 void PDFiumEngine::DeviceToPage(int page_index,
                                 float device_x,
                                 float device_y,
                                 double* page_x,
                                 double* page_y) {
   *page_x = *page_y = 0;
-  int temp_x = static_cast<int>((device_x + position_.x())/ current_zoom_ -
+  int temp_x = static_cast<int>((device_x + position_.x()) / current_zoom_ -
       pages_[page_index]->rect().x());
-  int temp_y = static_cast<int>((device_y + position_.y())/ current_zoom_ -
+  int temp_y = static_cast<int>((device_y + position_.y()) / current_zoom_ -
       pages_[page_index]->rect().y());
   FPDF_DeviceToPage(
       pages_[page_index]->GetPage(), 0, 0,
       pages_[page_index]->rect().width(),  pages_[page_index]->rect().height(),
       current_rotation_, temp_x, temp_y, page_x, page_y);
 }
 
 int PDFiumEngine::GetVisiblePageIndex(FPDF_PAGE page) {
   for (int page_index : visible_pages_) {
     if (pages_[page_index]->GetPage() == page)
       return page_index;
   }
   return -1;
 }
 
 void PDFiumEngine::SetCurrentPage(int index) {
   if (index == most_visible_page_ || !form_)
     return;
+
   if (most_visible_page_ != -1 && called_do_document_action_) {
     FPDF_PAGE old_page = pages_[most_visible_page_]->GetPage();
     FORM_DoPageAAction(old_page, form_, FPDFPAGE_AACTION_CLOSE);
   }
   most_visible_page_ = index;
 #if defined(OS_LINUX)
     g_last_instance_id = client_->GetPluginInstance()->pp_instance();
 #endif
   if (most_visible_page_ != -1 && called_do_document_action_) {
     FPDF_PAGE new_page = pages_[most_visible_page_]->GetPage();
@@ skipping 161 matching lines @@
 
 void PDFiumEngine::RotateInternal() {
   // Store the current find index so that we can resume finding at that
   // particular index after we have recomputed the find results.
   std::string current_find_text = current_find_text_;
   if (current_find_index_.valid())
     resume_find_index_.SetIndex(current_find_index_.GetIndex());
   else
     resume_find_index_.Invalidate();
 
+  // Save the current page.
+  int most_visible_page = most_visible_page_;
+
   InvalidateAllPages();
 
+  // Restore find results.
   if (!current_find_text.empty()) {
     // Clear the UI.
     client_->NotifyNumberOfFindResultsChanged(0, false);
     StartFind(current_find_text, false);
   }
+
+  // Restore current page. After a rotation, the page heights have changed but
+  // the scroll position has not. Readjust.

[raymes, 2016/08/22 01:09:30]

Possibly add a note that we should restore the position of that page?

[Lei Zhang, 2016/08/22 19:08:44]

Done.

+  client_->ScrollToPage(most_visible_page);
 }
 
 void PDFiumEngine::SetSelecting(bool selecting) {
   bool was_selecting = selecting_;
   selecting_ = selecting;
   if (selecting_ != was_selecting)
     client_->IsSelectingChanged(selecting);
 }
 
 void PDFiumEngine::Form_Invalidate(FPDF_FORMFILLINFO* param,
@@ skipping 535 matching lines @@
   FPDF_DOCUMENT doc =
       FPDF_LoadMemDocument(pdf_buffer, pdf_buffer_size, nullptr);
   if (!doc)
     return false;
   bool success = FPDF_GetPageSizeByIndex(doc, page_number, width, height) != 0;
   FPDF_CloseDocument(doc);
   return success;
 }
 
 }  // namespace chrome_pdf