Implement scroll to global point action in PDFiumEngine

This change adds the following
- Adds name PP_PDF_SCROLL_TO_GLOBAL_POINT in PP_PdfAccessibilityAction
  action enum.
- Handle PP_PDF_SCROLL_TO_GLOBAL_POINT action in PDFiumEngine.
  The action is used by certain screen readers to
  scroll content in viewport during continuous read operation.

Bug: 811233
Change-Id: I725a5295f42049af139856ce9815799cf67c0088
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1954800
Commit-Queue: Virender Singh <virens@microsoft.com>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Kevin Babbitt <kbabbitt@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#724911}

pdf/pdfium/accessibility_unittest.cc

@@ -337,6 +337,28 @@ TEST_F(AccessibilityTest, TestScrollToNearestEdge) {
   ComparePoint({-199, -199}, client.GetScrollRequestPoints());
 }
 
+TEST_F(AccessibilityTest, TestScrollToGlobalPoint) {
+  ScrollEnabledTestClient client;
+  std::unique_ptr<PDFiumEngine> engine = InitializeEngine(
+      &client, FILE_PATH_LITERAL("rectangles_multi_pages.pdf"));
+  ASSERT_TRUE(engine);
+  engine->PluginSizeUpdated({400, 400});
+  PP_PdfAccessibilityActionData action_data;
+  action_data.action = PP_PdfAccessibilityAction::PP_PDF_SCROLL_TO_GLOBAL_POINT;
+
+  // Scroll up if global point is below the target rect
+  action_data.target_rect = {{201, 201}, {10, 10}};
+  action_data.target_point = {230, 230};
+  engine->HandleAccessibilityAction(action_data);
+  ComparePoint({-29, -29}, client.GetScrollRequestPoints());
+
+  // Scroll down if global point is above the target rect
+  action_data.target_rect = {{230, 230}, {10, 10}};
+  action_data.target_point = {201, 201};
+  engine->HandleAccessibilityAction(action_data);
+  ComparePoint({29, 29}, client.GetScrollRequestPoints());
+}
+
 // This class is required to just override the NavigateTo
 // functionality for testing in a specific way. It will
 // keep the TestClient class clean for extension by others.

pdf/pdfium/pdfium_engine.cc

@@ -2024,6 +2024,10 @@ void PDFiumEngine::HandleAccessibilityAction(
       }
       break;
     }
+    case PP_PdfAccessibilityAction::PP_PDF_SCROLL_TO_GLOBAL_POINT: {
+      ScrollToGlobalPoint(action_data.target_rect, action_data.target_point);
+      break;
+    }
     default:
       NOTREACHED();
       break;
@@ -2197,6 +2201,12 @@ void PDFiumEngine::ScrollBasedOnScrollAlignment(
   client_->ScrollBy(scroll_offset);
 }
 
+void PDFiumEngine::ScrollToGlobalPoint(const pp::Rect& target_rect,
+                                       const pp::Point& global_point) {
+  pp::Point scroll_offset = GetScreenRect(target_rect).point();
+  client_->ScrollBy(scroll_offset - global_point);
+}
+
 base::Optional<PDFEngine::NamedDestination> PDFiumEngine::GetNamedDestination(
     const std::string& destination) {
   // Look for the destination.

pdf/pdfium/pdfium_engine.h

@@ -536,6 +536,11 @@ class PDFiumEngine : public PDFEngine,
       const PP_PdfAccessibilityScrollAlignment& horizontal_scroll_alignment,
       const PP_PdfAccessibilityScrollAlignment& vertical_scroll_alignment);
 
+  // Scrolls top left of a rect in page |target_rect| to |global_point|.
+  // Global point is point relative to viewport in screen.
+  void ScrollToGlobalPoint(const pp::Rect& target_rect,
+                           const pp::Point& global_point);
+
   // Set if the document has any local edits.
   void SetEditMode(bool edit_mode);
 

ppapi/c/private/ppp_pdf.h

@@ -67,8 +67,10 @@ typedef enum {
   PP_PDF_SCROLL_TO_MAKE_VISIBLE = 1,
   // Invokes default action on a node.
   PP_PDF_DO_DEFAULT_ACTION = 2,
+  // Action specifying a command to scroll to the global point.
+  PP_PDF_SCROLL_TO_GLOBAL_POINT = 3,
   // Last enum value marker.
-  PP_PDF_ACCESSIBILITYACTION_LAST = PP_PDF_DO_DEFAULT_ACTION
+  PP_PDF_ACCESSIBILITYACTION_LAST = PP_PDF_SCROLL_TO_GLOBAL_POINT
 } PP_PdfAccessibilityAction;
 PP_COMPILE_ASSERT_SIZE_IN_BYTES(PP_PdfAccessibilityAction, 4);
 
@@ -108,6 +110,8 @@ struct PP_PdfAccessibilityActionData {
   PP_PdfAccessibilityAction action;
   // Annotation type on which the action is to be performed.
   PP_PdfAccessibilityAnnotationType annotation_type;
+  // Target point on which the action is to be performed.
+  struct PP_Point target_point;
   // Target rect on which the action is to be performed.
   struct PP_Rect target_rect;
   // Index of annotation in page.
@@ -119,7 +123,7 @@ struct PP_PdfAccessibilityActionData {
   // Vertical scroll alignment with respect to the viewport
   PP_PdfAccessibilityScrollAlignment vertical_scroll_alignment;
 };
-PP_COMPILE_ASSERT_STRUCT_SIZE_IN_BYTES(PP_PdfAccessibilityActionData, 40);
+PP_COMPILE_ASSERT_STRUCT_SIZE_IN_BYTES(PP_PdfAccessibilityActionData, 48);
 
 struct PPP_Pdf_1_1 {
   // Returns an absolute URL if the position is over a link.

ppapi/proxy/ppapi_messages.h

@@ -237,6 +237,7 @@ IPC_STRUCT_TRAITS_END()
 IPC_STRUCT_TRAITS_BEGIN(PP_PdfAccessibilityActionData)
   IPC_STRUCT_TRAITS_MEMBER(action)
   IPC_STRUCT_TRAITS_MEMBER(annotation_type)
+  IPC_STRUCT_TRAITS_MEMBER(target_point)
   IPC_STRUCT_TRAITS_MEMBER(target_rect)
   IPC_STRUCT_TRAITS_MEMBER(annotation_index)
   IPC_STRUCT_TRAITS_MEMBER(page_index)