Preserving Text Selection during Page Rotation and 2-Up View Toggling

When viewing a PDF, if text is selected, it will remain highlighted
after rotating the page or toggling the 2-up view to ensure that the
text remains selected in the completed page layout.

Bug: 1420684
Change-Id: Ic3de70e543c7efd2370c00fc5cf4d59fc807ba11
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4940462
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1210558}

pdf/pdfium/pdfium_engine.cc

@@ -2147,11 +2147,13 @@ void PDFiumEngine::ZoomUpdated(double new_zoom_level) {
 }
 
 void PDFiumEngine::RotateClockwise() {
+  SaveSelection();
   desired_layout_options_.RotatePagesClockwise();
   ProposeNextDocumentLayout();
 }
 
 void PDFiumEngine::RotateCounterclockwise() {
+  SaveSelection();
   desired_layout_options_.RotatePagesCounterclockwise();
   ProposeNextDocumentLayout();
 }
@@ -2179,6 +2181,7 @@ void PDFiumEngine::SetReadOnly(bool enable) {
 }
 
 void PDFiumEngine::SetDocumentLayout(DocumentLayout::PageSpread page_spread) {
+  SaveSelection();
   desired_layout_options_.set_page_spread(page_spread);
   ProposeNextDocumentLayout();
 }
@@ -3808,6 +3811,8 @@ gfx::Size PDFiumEngine::ApplyDocumentLayout(
   // TODO(thestig): It would be better to also restore the position on the page.
   client_->ScrollToPage(most_visible_page);
 
+  RestoreSelection();
+
   return layout_.size();
 }
 
@@ -3922,6 +3927,22 @@ void PDFiumEngine::SetSelection(const PageCharacterIndex& selection_start_index,
   }
 }
 
+void PDFiumEngine::SaveSelection() {
+  // The PDFiumRange in the `selection_` has stored some previously cached
+  // information. The `saved_selection_` needs a fresh PDFiumRange for future
+  // use.
+  for (const auto& item : selection_) {
+    saved_selection_.push_back(PDFiumRange(
+        pages_[item.page_index()].get(), item.char_index(), item.char_count()));
+  }
+}
+
+void PDFiumEngine::RestoreSelection() {
+  if (!saved_selection_.empty()) {
+    selection_ = std::move(saved_selection_);
+  }
+}
+
 void PDFiumEngine::ScrollFocusedAnnotationIntoView() {
   FPDF_ANNOTATION annot;
   int page_index;

pdf/pdfium/pdfium_engine.h

@@ -612,6 +612,9 @@ class PDFiumEngine : public PDFEngine,
   void SetSelection(const PageCharacterIndex& selection_start_index,
                     const PageCharacterIndex& selection_end_index);
 
+  void SaveSelection();
+  void RestoreSelection();
+
   // Scroll the current focused annotation into view if not already in view.
   void ScrollFocusedAnnotationIntoView();
 
@@ -708,6 +711,11 @@ class PDFiumEngine : public PDFEngine,
   // There could be more than one range if selection spans more than one page.
   std::vector<PDFiumRange> selection_;
 
+  // When rotating the page or updating the PageSpread mode, used to store the
+  // contents of `selection_`. After the page change is completed, the contents
+  // of `selection_` are restored.
+  std::vector<PDFiumRange> saved_selection_;
+
   // True if we're in the middle of text selection.
   bool selecting_ = false;
 

pdf/pdfium/pdfium_engine_unittest.cc

@@ -924,6 +924,69 @@ TEST_P(PDFiumEngineTest, SelectTextWithNonPrintableCharacter) {
   EXPECT_EQ("Hello, world!", engine->GetSelectedText());
 }
 
+TEST_P(PDFiumEngineTest, RotateAfterSelectedText) {
+  NiceMock<MockTestClient> client;
+  std::unique_ptr<PDFiumEngine> engine =
+      InitializeEngine(&client, FILE_PATH_LITERAL("hello_world2.pdf"));
+  ASSERT_TRUE(engine);
+
+  // Plugin size chosen so all pages of the document are visible.
+  engine->PluginSizeUpdated({1024, 4096});
+
+  EXPECT_THAT(engine->GetSelectedText(), IsEmpty());
+
+  constexpr gfx::PointF kPosition(100, 120);
+  EXPECT_TRUE(engine->HandleInputEvent(
+      CreateLeftClickWebMouseEventAtPositionWithClickCount(kPosition, 2)));
+  EXPECT_EQ("Goodbye", engine->GetSelectedText());
+
+  DocumentLayout::Options options;
+  EXPECT_CALL(client, ProposeDocumentLayout(LayoutWithSize(276, 556)))
+      .WillOnce(Return());
+  engine->RotateClockwise();
+  options.RotatePagesClockwise();
+  engine->ApplyDocumentLayout(options);
+  EXPECT_EQ("Goodbye", engine->GetSelectedText());
+
+  EXPECT_CALL(client, ProposeDocumentLayout(LayoutWithSize(276, 556)))
+      .WillOnce(Return());
+  engine->RotateCounterclockwise();
+  options.RotatePagesCounterclockwise();
+  engine->ApplyDocumentLayout(options);
+  EXPECT_EQ("Goodbye", engine->GetSelectedText());
+}
+
+TEST_P(PDFiumEngineTest, MultiPagesPdfInTwoUpViewAfterSelectedText) {
+  NiceMock<MockTestClient> client;
+  std::unique_ptr<PDFiumEngine> engine =
+      InitializeEngine(&client, FILE_PATH_LITERAL("hello_world2.pdf"));
+  ASSERT_TRUE(engine);
+  // Plugin size chosen so all pages of the document are visible.
+  engine->PluginSizeUpdated({1024, 4096});
+
+  EXPECT_THAT(engine->GetSelectedText(), IsEmpty());
+
+  constexpr gfx::PointF kPosition(100, 120);
+  EXPECT_TRUE(engine->HandleInputEvent(
+      CreateLeftClickWebMouseEventAtPositionWithClickCount(kPosition, 2)));
+  EXPECT_EQ("Goodbye", engine->GetSelectedText());
+
+  DocumentLayout::Options options;
+  options.set_page_spread(DocumentLayout::PageSpread::kTwoUpOdd);
+  EXPECT_CALL(client, ProposeDocumentLayout(LayoutWithOptions(options)))
+      .WillOnce(Return());
+  engine->SetDocumentLayout(DocumentLayout::PageSpread::kTwoUpOdd);
+  engine->ApplyDocumentLayout(options);
+  EXPECT_EQ("Goodbye", engine->GetSelectedText());
+
+  options.set_page_spread(DocumentLayout::PageSpread::kOneUp);
+  EXPECT_CALL(client, ProposeDocumentLayout(LayoutWithOptions(options)))
+      .WillOnce(Return());
+  engine->SetDocumentLayout(DocumentLayout::PageSpread::kOneUp);
+  engine->ApplyDocumentLayout(options);
+  EXPECT_EQ("Goodbye", engine->GetSelectedText());
+}
+
 INSTANTIATE_TEST_SUITE_P(All, PDFiumEngineTest, testing::Bool());
 
 using PDFiumEngineDeathTest = PDFiumEngineTest;