a11y: Move CreateTextMarker[Range] to TextMarkerHelperMac.

ui/accessibility/platform/text_marker_helper_mac.mm

+// Copyright 2017 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.
+
+#import "ui/accessibility/platform/text_marker_helper_mac.h"
+
+#import <Cocoa/Cocoa.h>
+
+#import "base/mac/foundation_util.h"
+#include "base/mac/scoped_cftyperef.h"
+#include "ui/accessibility/ax_position.h"
+#include "ui/accessibility/ax_range.h"
+
+using ui::AXPositionPointer;
+using ui::AXRangePointer;
+using ui::AXPositionData;
+
+extern "C" {
+
+// The following are private accessibility APIs required for cursor navigation
+// and text selection. VoiceOver started relying on them in Mac OS X 10.11.
+AXTextMarkerRef AXTextMarkerCreate(CFAllocatorRef allocator,
+                                   const UInt8* bytes,
+                                   CFIndex length);
+
+AXTextMarkerRangeRef AXTextMarkerRangeCreate(CFAllocatorRef allocator,
+                                             AXTextMarkerRef start_marker,
+                                             AXTextMarkerRef end_marker);
+const UInt8* AXTextMarkerGetBytePtr(AXTextMarkerRef text_marker);
+size_t AXTextMarkerGetLength(AXTextMarkerRef text_marker);
+AXTextMarkerRef AXTextMarkerRangeCopyStartMarker(
+    AXTextMarkerRangeRef text_marker_range);
+AXTextMarkerRef AXTextMarkerRangeCopyEndMarker(
+    AXTextMarkerRangeRef text_marker_range);
+
+}  // extern "C"
+
+namespace {
+
+constexpr size_t kDataSize = sizeof(AXPositionData);
+
+// to call |release| on it to transfer ownership of the position to the text
+// marker object.
+id CreateTextMarker(AXPositionPointer position) {
+  AXPositionData data;
+  position->ToData(&data);
+
+  AXTextMarkerRef text_marker = AXTextMarkerCreate(
+      kCFAllocatorDefault, reinterpret_cast<const UInt8*>(&data), kDataSize);
+  return static_cast<id>(
+      base::mac::CFTypeRefToNSObjectAutorelease(text_marker));
+}
+
+// |range| is destructed at the end of this method and ownership of its |anchor|
+// and |focus| are transfered to the marker range object.
+id CreateTextMarkerRange(AXRangePointer range) {
+  AXPositionData anchor, focus;
+  range.first->ToData(&anchor);
+  range.second->ToData(&focus);
+
+  base::ScopedCFTypeRef<AXTextMarkerRef> start_marker(AXTextMarkerCreate(
+      kCFAllocatorDefault, reinterpret_cast<const UInt8*>(&anchor), kDataSize));
+  base::ScopedCFTypeRef<AXTextMarkerRef> end_marker(AXTextMarkerCreate(
+      kCFAllocatorDefault, reinterpret_cast<const UInt8*>(&focus), kDataSize));
+  AXTextMarkerRangeRef marker_range =
+      AXTextMarkerRangeCreate(kCFAllocatorDefault, start_marker, end_marker);
+  return static_cast<id>(
+      base::mac::CFTypeRefToNSObjectAutorelease(marker_range));
+}
+
+bool ExtractData(AXTextMarkerRef text_marker, AXPositionData* data) {
+  DCHECK(text_marker);
+
+  if (AXTextMarkerGetLength(text_marker) != kDataSize)
+    return false;
+
+  const UInt8* source_buffer = AXTextMarkerGetBytePtr(text_marker);
+  if (!source_buffer)
+    return false;
+
+  UInt8* destination_buffer = reinterpret_cast<UInt8*>(data);
+  std::memcpy(destination_buffer, source_buffer, kDataSize);
+  return true;
+}
+
+// Of two positions, returns the one that comes first (destroys the other).
+AXPositionPointer FirstOf(AXPositionPointer a, AXPositionPointer b) {
+  return b->Compare(a) ? std::move(b) : std::move(a);
+}
+
+}  // namespace
+
+@interface TextMarkerHelperMac ()
+- (AXPositionPointer)extractFrom:(id)parameter;
+@end
+
+@implementation TextMarkerHelperMac {
+  std::unique_ptr<ui::PositionFactory> factory_;
+}
+
+- (instancetype)initWithFactory:(std::unique_ptr<ui::PositionFactory>)factory {
+  if ((self = [super init])) {
+    factory_ = std::move(factory);
+  }
+  return self;
+}
+
+- (id)startTextMarker {
+  AXPositionPointer root = factory_->GetRoot();
+  return root ? CreateTextMarker(root->PositionAtStartOfAnchor()) : nil;
+}
+
+- (id)endTextMarker {
+  AXPositionPointer root = factory_->GetRoot();
+  return root ? CreateTextMarker(root->PositionAtEndOfAnchor()) : nil;
+}
+
+- (id)selectedTextMarkerRange {
+  AXRangePointer selection = factory_->GetSelection();
+  if (!selection.first || !selection.second)
+    return nil;
+  return CreateTextMarkerRange(std::move(selection));
+}
+
+- (AXPositionPointer)extractFrom:(id)parameter {
+  AXPositionData data;
+  if (ExtractData(base::mac::CFCastStrict<AXTextMarkerRef>(parameter), &data))
+    return factory_->GetFromData(data);
+  return factory_->GetFromData(ui::AXAbstractPosition::kNullData);
+}
+
+- (id)AXTextMarkerRangeForUIElement:(id)parameter {
+  AXPositionPointer startPosition = factory_->GetRoot();
+  AXPositionPointer endPosition = startPosition->PositionAtEndOfAnchor();
+  AXRangePointer range =
+      AXRangePointer(std::move(startPosition), std::move(endPosition));
+  return CreateTextMarkerRange(std::move(range));
+}
+
+- (id)AXUIElementForTextMarker:(id)parameter {
+  AXPositionData data;
+  if (ExtractData(base::mac::CFCastStrict<AXTextMarkerRef>(parameter), &data))
+    return factory_->GetAccessibilityObject(data);
+  return nil;
+}
+
+- (id)AXNextTextMarkerForTextMarker:(id)parameter {
+  AXPositionPointer position = [self extractFrom:parameter];
+  if (position->IsNull())
+    return nil;
+  return CreateTextMarker(position->NextCharacterPosition());
+}
+
+- (id)AXPreviousTextMarkerForTextMarker:(id)parameter {
+  AXPositionPointer position = [self extractFrom:parameter];
+  if (position->IsNull())
+    return nil;
+  return CreateTextMarker(position->PreviousCharacterPosition());
+}
+
+- (id)AXLeftWordTextMarkerRangeForTextMarker:(id)parameter {
+  AXPositionPointer endPosition = [self extractFrom:parameter];
+  if (endPosition->IsNull())
+    return nil;
+
+  AXPositionPointer startPosition =
+      FirstOf(endPosition->PreviousWordStartPosition(),
+              endPosition->PreviousWordEndPosition());
+  AXRangePointer range(std::move(startPosition), std::move(endPosition));
+  return CreateTextMarkerRange(std::move(range));
+}
+
+- (id)AXRightWordTextMarkerRangeForTextMarker:(id)parameter {
+  AXPositionPointer startPosition = [self extractFrom:parameter];
+  if (startPosition->IsNull())
+    return nil;
+
+  AXPositionPointer endPosition =
+      FirstOf(startPosition->NextWordEndPosition(),
+              startPosition->NextWordStartPosition());
+  AXRangePointer range(std::move(startPosition), std::move(endPosition));
+  return CreateTextMarkerRange(std::move(range));
+}
+
+- (id)AXNextWordEndTextMarkerForTextMarker:(id)parameter {
+  AXPositionPointer position = [self extractFrom:parameter];
+  if (position->IsNull())
+    return nil;
+  return CreateTextMarker(position->NextWordEndPosition());
+}
+
+- (id)AXPreviousWordStartTextMarkerForTextMarker:(id)parameter {
+  AXPositionPointer position = [self extractFrom:parameter];
+  if (position->IsNull())
+    return nil;
+  return CreateTextMarker(position->PreviousWordStartPosition());
+}
+
+- (id)AXTextMarkerRangeForLine:(id)parameter {
+  AXPositionPointer position = [self extractFrom:parameter];
+  if (position->IsNull())
+    return nil;
+
+  AXPositionPointer startPosition = position->PreviousLineStartPosition();
+  AXPositionPointer endPosition = position->NextLineEndPosition();
+  AXRangePointer range(std::move(startPosition), std::move(endPosition));
+  return CreateTextMarkerRange(std::move(range));
+}
+
+- (id)AXLeftLineTextMarkerRangeForTextMarker:(id)parameter {
+  AXPositionPointer endPosition = [self extractFrom:parameter];
+  if (endPosition->IsNull())
+    return nil;
+
+  AXPositionPointer startPosition =
+      FirstOf(endPosition->PreviousLineStartPosition(),
+              endPosition->PreviousLineEndPosition());
+  AXRangePointer range(std::move(startPosition), std::move(endPosition));
+  return CreateTextMarkerRange(std::move(range));
+}
+
+- (id)AXRightLineTextMarkerRangeForTextMarker:(id)parameter {
+  AXPositionPointer startPosition = [self extractFrom:parameter];
+  if (startPosition->IsNull())
+    return nil;
+
+  AXPositionPointer endPosition =
+      FirstOf(startPosition->NextLineStartPosition(),
+              startPosition->NextLineEndPosition());
+  AXRangePointer range(std::move(startPosition), std::move(endPosition));
+  return CreateTextMarkerRange(std::move(range));
+}
+
+- (id)AXNextLineEndTextMarkerForTextMarker:(id)parameter {
+  AXPositionPointer position = [self extractFrom:parameter];
+  if (position->IsNull())
+    return nil;
+  return CreateTextMarker(position->NextLineEndPosition());
+}
+
+- (id)AXPreviousLineStartTextMarkerForTextMarker:(id)parameter {
+  AXPositionPointer position = [self extractFrom:parameter];
+  if (position->IsNull())
+    return nil;
+  return CreateTextMarker(position->PreviousLineStartPosition());
+}
+
+- (id)AXLineTextMarkerRangeForTextMarker:(id)parameter {
+  AXPositionPointer position = [self extractFrom:parameter];
+  if (position->IsNull())
+    return nil;
+
+  AXRangePointer range(position->PreviousLineStartPosition(),
+                       position->NextLineEndPosition());
+  return CreateTextMarkerRange(std::move(range));
+}
+
+- (id)AXTextMarkerRangeForUnorderedTextMarkers:(id)parameter {
+  if (![parameter isKindOfClass:[NSArray class]])
+    return nil;
+
+  NSArray* textMarkerArray = parameter;
+  if ([textMarkerArray count] != 2)
+    return nil;
+
+  AXPositionPointer startPosition =
+      [self extractFrom:[textMarkerArray objectAtIndex:0]];
+  AXPositionPointer endPosition =
+      [self extractFrom:[textMarkerArray objectAtIndex:1]];
+  if (endPosition->Compare(startPosition)) {
+    return CreateTextMarkerRange(
+        AXRangePointer(std::move(endPosition), std::move(startPosition)));
+  }
+  return CreateTextMarkerRange(
+      AXRangePointer(std::move(startPosition), std::move(endPosition)));
+}
+
++ (BOOL)getRangeDataFromMarkerRange:(id)parameter
+                              start:(ui::AXPositionData*)start
+                                end:(ui::AXPositionData*)end {
+  AXTextMarkerRangeRef markerRange =
+      base::mac::CFCastStrict<AXTextMarkerRangeRef>(parameter);
+  DCHECK(markerRange);
+
+  base::ScopedCFTypeRef<AXTextMarkerRef> startMarker(
+      AXTextMarkerRangeCopyStartMarker(markerRange));
+  base::ScopedCFTypeRef<AXTextMarkerRef> endMarker(
+      AXTextMarkerRangeCopyEndMarker(markerRange));
+  if (!startMarker || !endMarker)
+    return NO;
+
+  return ExtractData(startMarker, start) && ExtractData(endMarker, end);
+}
+
+@end