PDF Viewer - Search results don't work after rotating pdf

Currently search results are cleared when user rotates
pdf document. As a result, the forward/backward buttons in
find bar do not work if user rotates pdf document after
finding some text in the document.

This happens because |find_results_| is cleared in the method
InvalidateAllPages(), which is called after rotation.

This patch introduces a new method to restore find results state
after invalidate operation is done. New find operation is done
to ensure rects are correctly identified for search results and
correct region is highlighted on pressing forward/backward buttons
in find bar.

BUG=389782

Review URL: https://codereview.chromium.org/555803002

Cr-Commit-Position: refs/heads/master@{#298083}

pdf/pdfium/pdfium_engine.cc

@@ -567,6 +567,7 @@ PDFiumEngine::PDFiumEngine(PDFEngine::Client* client)
       last_page_to_search_(-1),
       last_character_index_to_search_(-1),
       current_find_index_(-1),
+      resume_find_index_(-1),
       permissions_(0),
       fpdf_availability_(NULL),
       next_timer_id_(0),
@@ -1683,6 +1684,12 @@ void PDFiumEngine::StartFind(const char* text, bool case_sensitive) {
   if (end_of_search) {
     // Send the final notification.
     client_->NotifyNumberOfFindResultsChanged(find_results_.size(), true);
+
+    // When searching is complete, resume finding at a particular index.
+    if (resume_find_index_ != -1) {
+      current_find_index_ = resume_find_index_;
+      resume_find_index_ = -1;
+    }
   } else {
     pp::CompletionCallback callback =
         find_factory_.NewCallback(&PDFiumEngine::ContinueFind);
@@ -1778,7 +1785,7 @@ void PDFiumEngine::AddFindResult(const PDFiumRange& result) {
   find_results_.insert(find_results_.begin() + i, result);
   UpdateTickMarks();
 
-  if (current_find_index_ == -1) {
+  if (current_find_index_ == -1 && resume_find_index_ == -1) {
     // Select the first match.
     SelectFindResult(true);
   } else if (static_cast<int>(i) <= current_find_index_) {
@@ -1886,21 +1893,36 @@ void PDFiumEngine::ZoomUpdated(double new_zoom_level) {
 
 void PDFiumEngine::RotateClockwise() {
   current_rotation_ = (current_rotation_ + 1) % 4;
+
+  // 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_;
+  resume_find_index_ = current_find_index_;
+
   InvalidateAllPages();
+
+  if (!current_find_text.empty())
+    StartFind(current_find_text.c_str(), false);
 }
 
 void PDFiumEngine::RotateCounterclockwise() {
   current_rotation_ = (current_rotation_ - 1) % 4;
+
+  // 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_;
+  resume_find_index_ = current_find_index_;
+
   InvalidateAllPages();
+
+  if (!current_find_text.empty())
+    StartFind(current_find_text.c_str(), false);
 }
 
 void PDFiumEngine::InvalidateAllPages() {
-  selection_.clear();
-  find_results_.clear();
-
   CancelPaints();
+  StopFind();
   LoadPageInfo(true);
-  UpdateTickMarks();
   client_->Invalidate(pp::Rect(plugin_size_));
 }
 

pdf/pdfium/pdfium_engine.h

@@ -541,6 +541,8 @@ class PDFiumEngine : public PDFEngine,
   int last_character_index_to_search_;  // -1 if search until end of page.
   // Which result the user has currently selected.
   int current_find_index_;
+  // Where to resume searching.
+  int resume_find_index_;
 
   // Permissions bitfield.
   unsigned long permissions_;