[ios] Read out currently selected match and words before and after match

To improve accessibility, the selectAndScrollToVisibleMatch() JavaScript
function will now also return a string containing the selected match
and words in the nodes before and after the match. This string will
then be sent out as a UIAccessibilityAnnouncementNotification.

Bug: 979707
Change-Id: I767530460b5d58c8d99bda3feb2fe29c56fb5f62
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1857280
Commit-Queue: Chris Lu <thegreenfrog@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Reviewed-by: Yi Su <mrsuyi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707847}

ios/chrome/browser/find_in_page/find_in_page_controller.mm

@@ -402,7 +402,12 @@ static NSString* gSearchTerm;
 
 - (void)findInPageManager:(web::FindInPageManager*)manager
     didSelectMatchAtIndex:(NSInteger)index
+        withContextString:(NSString*)contextString
               forWebState:(web::WebState*)webState {
+  if (contextString) {
+    UIAccessibilityPostNotification(UIAccessibilityAnnouncementNotification,
+                                    contextString);
+  }
   // Increment index so that match number show in FindBar ranges from 1...N as
   // opposed to 0...N-1.
   index++;

ios/web/find_in_page/find_in_page_constants.h

@@ -19,6 +19,9 @@ extern const char kSelectAndScrollResultMatches[];
 // Dictionary key that holds value of currently selected index in
 // kFindInPageSelectAndScrollToMatch resoonse.
 extern const char kSelectAndScrollResultIndex[];
+// Dictionary key in kFindInPageSelectAndScrollToMatch response that
+// holds the value of the context for the currently selected match.
+extern const char kSelectAndScrollResultContextString[];
 // The name of JavaScript function which stops Find in Page.
 extern const char kFindInPageStop[];
 

ios/web/find_in_page/find_in_page_constants.mm

@@ -21,6 +21,8 @@ const char kSelectAndScrollResultMatches[] = "matches";
 
 const char kSelectAndScrollResultIndex[] = "index";
 
+const char kSelectAndScrollResultContextString[] = "contextString";
+
 const char kFindInPageStop[] = "findInPage.stop";
 
 }  // namespace web

ios/web/find_in_page/find_in_page_manager_delegate_bridge.mm

@@ -32,13 +32,15 @@ void FindInPageManagerDelegateBridge::DidHighlightMatches(WebState* web_state,
 }
 
 void FindInPageManagerDelegateBridge::DidSelectMatch(WebState* web_state,
-                                                     int index) {
+                                                     int index,
+                                                     NSString* context_string) {
   if ([delegate_ respondsToSelector:@selector
-                 (findInPageManager:didSelectMatchAtIndex:forWebState:)]) {
+                 (findInPageManager:
+                     didSelectMatchAtIndex:withContextString:forWebState:)]) {
     [delegate_ findInPageManager:web::FindInPageManager::FromWebState(web_state)
            didSelectMatchAtIndex:index
+               withContextString:context_string
                      forWebState:web_state];
   }
 }
-
 }

ios/web/find_in_page/find_in_page_manager_delegate_bridge_unittest.mm

@@ -41,9 +41,10 @@ TEST_F(FindInPageManagerDelegateBridgeTest, DidHighlightMatches) {
 // Tests that CRWFindInPageManagerDelegate properly receives values from
 // DidSelectMatch().
 TEST_F(FindInPageManagerDelegateBridgeTest, DidSelectMatch) {
-  bridge_->DidSelectMatch(&test_web_state_, 1);
+  bridge_->DidSelectMatch(&test_web_state_, 1, @"match context");
   EXPECT_EQ(1, delegate_.index);
   EXPECT_EQ(&test_web_state_, delegate_.webState);
+  EXPECT_EQ(@"match context", delegate_.contextString);
 }
 
 }  // namespace web

ios/web/find_in_page/find_in_page_manager_impl.mm

@@ -226,6 +226,7 @@ void FindInPageManagerImpl::LastFindRequestCompleted() {
 }
 
 void FindInPageManagerImpl::SelectDidFinish(const base::Value* result) {
+  std::string match_context_string;
   if (result && result->is_dict()) {
     // Get updated match count.
     const base::Value* matches = result->FindKey(kSelectAndScrollResultMatches);
@@ -246,10 +247,18 @@ void FindInPageManagerImpl::SelectDidFinish(const base::Value* result) {
       int current_index = static_cast<int>(index->GetDouble());
       last_find_request_.SetCurrentSelectedMatchFrameIndex(current_index);
     }
+    // Get context string.
+    const base::Value* context_string =
+        result->FindKey(kSelectAndScrollResultContextString);
+    if (context_string && context_string->is_string()) {
+      match_context_string =
+          static_cast<std::string>(context_string->GetString());
+    }
   }
   if (delegate_) {
     delegate_->DidSelectMatch(
-        web_state_, last_find_request_.GetCurrentSelectedMatchPageIndex());
+        web_state_, last_find_request_.GetCurrentSelectedMatchPageIndex(),
+        base::SysUTF8ToNSString(match_context_string));
   }
 }
 

ios/web/public/find_in_page/find_in_page_manager_delegate.h

@@ -32,12 +32,17 @@ class FindInPageManagerDelegate {
                                    int match_count,
                                    NSString* query) = 0;
 
-  // Called when a match number |index| is selected. A selected match refers to
-  // a match that is highlighted in a unique manner different from the other
-  // matches. This is triggered by calling FindInPageManager::Find() with any
-  // FindInPageOptions to indicate the new match number that was selected. This
-  // method is not called if |FindInPageManager::Find| did not find any matches.
-  virtual void DidSelectMatch(WebState* web_state, int index) = 0;
+  // Called when a match number |index| is selected with |context_string|
+  // representing the text context of the match phrase. |context_string| can be
+  // used in VoiceOver to notify the user of the context of the match in the
+  // sentence. A selected match refers to a match that is
+  // highlighted in a unique manner different from the other matches. This is
+  // triggered by calling FindInPageManager::Find() with any FindInPageOptions
+  // to indicate the new match number that was selected. This method is not
+  // called if |FindInPageManager::Find| did not find any matches.
+  virtual void DidSelectMatch(WebState* web_state,
+                              int index,
+                              NSString* context_string) = 0;
 
  protected:
   virtual ~FindInPageManagerDelegate() = default;

ios/web/public/find_in_page/find_in_page_manager_delegate_bridge.h

@@ -27,13 +27,17 @@ class FindInPageManager;
     didHighlightMatchesOfQuery:(NSString*)query
                 withMatchCount:(NSInteger)matchCount
                    forWebState:(web::WebState*)webState;
-// Called when a match number |index| is selected. A selected match refers to
-// a match that is highlighted in a unique manner different from the other
-// matches. This is triggered by calling FindInPageManager::Find() with any
-// FindInPageOptions to indicate the new match number that was selected. This
-// method is not called if |FindInPageManager::Find| did not find any matches.
+// Called when a match number |index| is selected with |contextString|
+// representing the textual context of the match. |contextString| can be used
+// in VoiceOver to notify the user of the context of the match in the sentence.
+// A selected match refers to a match that is highlighted in a unique manner
+// different from the other matches. This is triggered by calling
+// FindInPageManager::Find() with any FindInPageOptions to indicate the new
+// match number that was selected. This method is not called if
+// |FindInPageManager::Find| did not find any matches.
 - (void)findInPageManager:(web::FindInPageManager*)manager
     didSelectMatchAtIndex:(NSInteger)index
+        withContextString:(NSString*)contextString
               forWebState:(web::WebState*)webState;
 @end
 
@@ -53,7 +57,9 @@ class FindInPageManagerDelegateBridge : public web::FindInPageManagerDelegate {
   void DidHighlightMatches(WebState* web_state,
                            int match_count,
                            NSString* query) override;
-  void DidSelectMatch(WebState* web_state, int index) override;
+  void DidSelectMatch(WebState* web_state,
+                      int index,
+                      NSString* context_string) override;
 
  private:
   __weak id<CRWFindInPageManagerDelegate> delegate_ = nil;

ios/web/public/test/fakes/crw_fake_find_in_page_manager_delegate.h

@@ -25,6 +25,7 @@ class WebState;
                    forWebState:(web::WebState*)webState;
 - (void)findInPageManager:(web::FindInPageManager*)manager
     didSelectMatchAtIndex:(NSInteger)index
+        withContextString:(NSString*)contextString
               forWebState:(web::WebState*)webState;
 
 // The last web::WebState received in delegate method calls.
@@ -35,6 +36,8 @@ class WebState;
 @property(nonatomic, readonly) NSInteger matchCount;
 // The last |index| passed in |didSelectMatchAtIndex:|.
 @property(nonatomic, readonly) NSInteger index;
+// The last |contextString| passed in |didSelectMatchAtIndex:|.
+@property(nonatomic, readonly) NSString* contextString;
 
 @end
 

ios/web/public/test/fakes/crw_fake_find_in_page_manager_delegate.mm

@@ -21,8 +21,10 @@
 
 - (void)findInPageManager:(web::FindInPageManager*)manager
     didSelectMatchAtIndex:(NSInteger)index
+        withContextString:(NSString*)contextString
               forWebState:(web::WebState*)webState {
   _webState = webState;
+  _contextString = [contextString copy];
   _index = index;
 }
 

ios/web/public/test/fakes/fake_find_in_page_manager_delegate.h

@@ -24,7 +24,9 @@ class FakeFindInPageManagerDelegate : public FindInPageManagerDelegate {
   void DidHighlightMatches(WebState* web_state,
                            int match_count,
                            NSString* query) override;
-  void DidSelectMatch(WebState* web_state, int index) override;
+  void DidSelectMatch(WebState* web_state,
+                      int index,
+                      NSString* context_string) override;
 
   // Holds the state passed to DidHighlightMatches and DidSelectMatch.
   struct State {
@@ -34,6 +36,7 @@ class FakeFindInPageManagerDelegate : public FindInPageManagerDelegate {
     int match_count = -1;
     NSString* query;
     int index = -1;
+    NSString* context_string;
   };
 
   // Returns the current State.

ios/web/public/test/fakes/fake_find_in_page_manager_delegate.mm

@@ -28,12 +28,14 @@ void FakeFindInPageManagerDelegate::DidHighlightMatches(WebState* web_state,
 }
 
 void FakeFindInPageManagerDelegate::DidSelectMatch(WebState* web_state,
-                                                   int index) {
+                                                   int index,
+                                                   NSString* context_string) {
   if (!delegate_state_) {
     delegate_state_ = std::make_unique<State>();
   }
   delegate_state_->web_state = web_state;
   delegate_state_->index = index;
+  delegate_state_->context_string = context_string;
 }
 
 }  // namespace web

ios/web/web_state/js/find_in_page_js_unittest.mm

@@ -198,9 +198,10 @@ TEST_F(FindInPageJsTest, FindAcrossMultipleNodes) {
   }));
 }
 
-// Tests that a FindInPage match can be highlighted.
+// Tests that a FindInPage match can be highlighted and the correct
+// accessibility string is returned.
 TEST_F(FindInPageJsTest, FindHighlightMatch) {
-  ASSERT_TRUE(LoadHtml("<span>foo</span>"));
+  ASSERT_TRUE(LoadHtml("<span>some foo match</span>"));
   const base::TimeDelta kCallJavascriptFunctionTimeout =
       base::TimeDelta::FromSeconds(kWaitForJSCompletionTimeout);
   ASSERT_TRUE(WaitUntilConditionOrTimeout(kWaitForJSCompletionTimeout, ^{
@@ -225,12 +226,15 @@ TEST_F(FindInPageJsTest, FindHighlightMatch) {
   }));
 
   __block bool highlight_done = false;
+  __block std::string context_string;
   std::vector<base::Value> highlight_params;
   highlight_params.push_back(base::Value(0));
   main_web_frame()->CallJavaScriptFunction(
       kFindInPageSelectAndScrollToMatch, highlight_params,
       base::BindOnce(^(const base::Value* result) {
         highlight_done = true;
+        context_string =
+            result->FindKey(kSelectAndScrollResultContextString)->GetString();
       }),
       kCallJavascriptFunctionTimeout);
   ASSERT_TRUE(WaitUntilConditionOrTimeout(kWaitForJSCompletionTimeout, ^{
@@ -240,12 +244,13 @@ TEST_F(FindInPageJsTest, FindHighlightMatch) {
   EXPECT_NSEQ(@1,
               ExecuteJavaScript(
                   @"document.getElementsByClassName('find_selected').length"));
+  EXPECT_EQ("some foo match", context_string);
 }
 
 // Tests that a FindInPage match can be highlighted and that a previous
 // highlight is removed when another match is highlighted.
 TEST_F(FindInPageJsTest, FindHighlightSeparateMatches) {
-  ASSERT_TRUE(LoadHtml("<span>foo foo</span>"));
+  ASSERT_TRUE(LoadHtml("<span>foo foo match</span>"));
   const base::TimeDelta kCallJavascriptFunctionTimeout =
       base::TimeDelta::FromSeconds(kWaitForJSCompletionTimeout);
   ASSERT_TRUE(WaitUntilConditionOrTimeout(kWaitForJSCompletionTimeout, ^{
@@ -270,18 +275,22 @@ TEST_F(FindInPageJsTest, FindHighlightSeparateMatches) {
   }));
 
   __block bool highlight_done = false;
+  __block std::string context_string;
   std::vector<base::Value> highlight_params;
   highlight_params.push_back(base::Value(0));
   main_web_frame()->CallJavaScriptFunction(
       kFindInPageSelectAndScrollToMatch, highlight_params,
       base::BindOnce(^(const base::Value* result) {
         highlight_done = true;
+        context_string =
+            result->FindKey(kSelectAndScrollResultContextString)->GetString();
       }),
       kCallJavascriptFunctionTimeout);
   ASSERT_TRUE(WaitUntilConditionOrTimeout(kWaitForJSCompletionTimeout, ^{
     return highlight_done;
   }));
 
+  EXPECT_EQ("foo ", context_string);
   EXPECT_NSEQ(@1,
               ExecuteJavaScript(
                   @"document.getElementsByClassName('find_selected').length"));
@@ -293,12 +302,15 @@ TEST_F(FindInPageJsTest, FindHighlightSeparateMatches) {
       kFindInPageSelectAndScrollToMatch, highlight_second_params,
       base::BindOnce(^(const base::Value* result) {
         highlight_done = true;
+        context_string =
+            result->FindKey(kSelectAndScrollResultContextString)->GetString();
       }),
       kCallJavascriptFunctionTimeout);
   ASSERT_TRUE(WaitUntilConditionOrTimeout(kWaitForJSCompletionTimeout, ^{
     return highlight_done;
   }));
 
+  EXPECT_EQ(" foo match", context_string);
   id inner_html = ExecuteJavaScript(@"document.body.innerHTML");
   ASSERT_TRUE([inner_html isKindOfClass:[NSString class]]);
   EXPECT_TRUE([inner_html

ios/web/web_state/js/resources/find_in_page.js

@@ -668,10 +668,37 @@ __gCrWeb.findInPage.selectAndScrollToVisibleMatch = function(index) {
   selectedMatchIndex_ = total_match_index;
   selectedVisibleMatchIndex_ = index;
 
-  getCurrentSelectedMatch_().addSelectHighlight();
+  match = getCurrentSelectedMatch_();
+  match.addSelectHighlight();
   scrollToCurrentlySelectedMatch_();
 
-  return {matches: visibleMatchCount, index: index};
+  // Get string consisting of the text contents of the match nodes and the
+  // nodes before and after them, if applicable.
+  // This will be read out as an accessibility notification for the match.
+  // The siblings's textContent are added into the node array, because the
+  // nextSibling and previousSibling properties to the match nodes sometimes
+  // are text nodes, not HTML nodes. This results in '[object Text]' string
+  // being added to the array instead of the object.
+  let nodes = match.nodes.slice();
+  if (match.nodes[0].previousSibling) {
+    nodes.unshift([match.nodes[0].previousSibling.textContent]);
+  }
+  if (match.nodes[match.nodes.length-1].nextSibling) {
+    nodes.push([match.nodes[match.nodes.length-1].nextSibling.textContent]);
+  }
+  let contextString = nodes.map(function(node) {
+    if (node.textContent) {
+      return node.textContent;
+    } else {
+      return node;
+    }
+  }).join("");
+
+  return {
+    matches: visibleMatchCount,
+    index: index,
+    contextString: contextString
+  };
 };
 
 /**