Classes/GTXAccessibilityTree.m - external/github.com/google/GTXiLib - Git at Google

 //
 // Copyright 2018 Google Inc.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //      http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 //

 #import <UIKit/UIKit.h>

 #import "GTXAccessibilityTree.h"

 #import "GTXAssertions.h"
 #import "GTXTreeIteratorContext.h"

 /**
  * There seems to be errors in accessibility children reported by some UIKit classes especially
  * UITextEffectsWindow which reports 9223372036854775807 possibly due to internal type conversions
  * with -1, we use this bounds value to detect that case..
  */
 static const NSInteger kAccessibilityChildrenUpperBound = 50000;

 /**
  * The class name for @c UIPickerTableView elements. Must be accessed via @c NSClassFromString
  * because it is a private class.
  */
 static NSString *const kUIPickerTableViewClassName = @"UIPickerTableView";

 /**
  * The class name for accessibility children of @c UIPickerTableView elements. Must be accessed via
  * @c NSClassFromString because it is a private class.
  */
 static NSString *const kUIPickerTableViewAccessibilityElementClassName =
     @"UITableViewCellAccessibilityElement";

 @implementation GTXAccessibilityTree {
   // Context for this object's NSEnumerator.
   GTXTreeIteratorContext *_enumeratorContext;

   // Root elements that this object handles.
   NSArray *_rootElements;
 }

 - (instancetype)initWithRootElements:(NSArray *)rootElements {
   self = [super init];
   if (self) {
     for (id element in rootElements) {
       if ([element isKindOfClass:[UIViewController class]]) {
         GTX_ASSERT(NO,
                    @"Invalid root element %@ found. Check GTXToolkit docs to learn more about "
                    @"valid root elements. Did you mean to use the .view property instead?",
                    element);
       }
     }

     _enumeratorContext = [[GTXTreeIteratorContext alloc] initWithElements:rootElements];
     _rootElements = rootElements;
   }
   return self;
 }

 - (void)iterateAllElementsWithBlock:(GTXTreeIterationBlock)block {
   // Create a new tree object for iteration since the current object may be in the middle of a
   // for-in loop.
   GTXAccessibilityTree *tree = [[GTXAccessibilityTree alloc] initWithRootElements:_rootElements];
   GTXTreeIteratorElement *iteratorElement;
   while ((iteratorElement = [tree gtx_nextObject])) {
     block(iteratorElement);
   }
 }

 #pragma mark - NSEnumerator

 - (id)nextObject {
   id nextObject = [self gtx_nextObject].current;
   if (!nextObject) {
     // Allow the tree object to be re-enumerated once through.
     _enumeratorContext = [[GTXTreeIteratorContext alloc] initWithElements:_rootElements];
   }
   return nextObject;
 }

 #pragma mark - NSExtendedEnumerator

 - (NSArray *)allObjects {
   NSMutableArray *allObjects = [[NSMutableArray alloc] init];
   [self iterateAllElementsWithBlock:^(GTXTreeIteratorElement *_Nonnull iteratorElement) {
     [allObjects addObject:iteratorElement.current];
   }];
   return allObjects;
 }

 #pragma mark - Private

 /**
  *  @return The next @c GTXTreeIteratorElement for the current @c GTXTreeIteratorContext.
  */
 - (GTXTreeIteratorElement *)gtx_nextObject {
   if (![_enumeratorContext hasElementsInQueue]) {
     return nil;
   }

   id nextInQueue;
   GTXTreeIteratorElement *nextIterationElementInQueue;
   // Get the next "unvisited" element.
   do {
     GTXTreeIteratorElement *nextIterationElementCandidate = [_enumeratorContext peekNextElement];
     id nextCandidate = nextIterationElementCandidate.current;
     [_enumeratorContext dequeueNextElement];
     if (![_enumeratorContext didVisitElement:nextCandidate]) {
       if (![self gtx_isAccessibilityHiddenElement:nextCandidate]) {
         nextInQueue = nextCandidate;
         nextIterationElementInQueue = nextIterationElementCandidate;
       }
     }
   } while ([_enumeratorContext hasElementsInQueue] && !nextInQueue);
   if (!nextInQueue) {
     return nil;
   }
   [_enumeratorContext visitElement:nextInQueue];
   if ([nextInQueue respondsToSelector:@selector(isAccessibilityElement)]) {
     if (![nextInQueue isAccessibilityElement]) {
       // nextInQueue could be an accessibility container, if so enqueue its children.
       // There are two ways of getting the children of an accessibility container:
       // First, using @selector(accessibilityElements)
       NSArray *axElements = [self gtx_accessibilityElementsOfElement:nextInQueue];

       // Second, using @selector(accessibilityElementAtIndex:)
       NSArray *axElementsFromIndices =
           [self gtx_accessibilityElementsFromIndicesOfElement:nextInQueue];

       // Ensure that either the children are available only through one method or elements via both
       // are the same. Otherwise we must fail as the the accessibility tree is inconsistent.
       if (axElements && axElementsFromIndices) {
         NSSet *accessibilityElementsSet = [NSSet setWithArray:axElements];
         NSSet *accessibilityElementsFromIndicesSet = [NSSet setWithArray:axElementsFromIndices];
         NSAssert([accessibilityElementsSet isEqualToSet:accessibilityElementsFromIndicesSet],
                  @"Accessibility elements obtained from -accessibilityElements and"
                  @" -accessibilityElementAtIndex: are different - they must not be. Either provide"
                  @" elements via one method or provide the same elements.\nDetails:\nElements via"
                  @" accessibilityElements:%@\nElements via accessibilityElementAtIndex:\n"
                  @"accessibilityElementCount:%@\nElements:%@",
                  accessibilityElementsSet, @([nextInQueue accessibilityElementCount]),
                  accessibilityElementsFromIndicesSet);

         // Ensure accessibilityElements* are marked as used even if NSAssert is removed.
         (void)accessibilityElementsSet;
         (void)accessibilityElementsFromIndicesSet;
       } else {
         // Set accessibilityElements to whichever is non nil or leave it as is.
         axElements = axElementsFromIndices ? axElementsFromIndices : axElements;
       }
       if (![nextInQueue respondsToSelector:@selector(accessibilityElementsHidden)] ||
           ![nextInQueue accessibilityElementsHidden]) {
         for (id element in axElements) {
           if (![_enumeratorContext didVisitElement:element]) {
             [_enumeratorContext
                 queueElement:[[GTXTreeIteratorElement alloc] initWithElement:element
                                                                  inContainer:nextInQueue]];
           }
         }
       }

       // nextInQueue could be a UIView subclass, if so enqueue its subviews.
       NSArray *subViews;
       if ([nextInQueue isKindOfClass:[UITableViewCell class]] ||
           [nextInQueue isKindOfClass:[UICollectionViewCell class]]) {
         subViews = [nextInQueue contentView].subviews;
       } else if ([nextInQueue respondsToSelector:@selector(subviews)]) {
         subViews = [nextInQueue subviews];
       }
       if ([nextInQueue respondsToSelector:@selector(isHidden)] && ![nextInQueue isHidden]) {
         for (id child in subViews) {
           if (![_enumeratorContext didVisitElement:child]) {
             [_enumeratorContext
                 queueElement:[[GTXTreeIteratorElement alloc] initWithElement:child
                                                                  inContainer:nextInQueue]];
           }
         }
       }
     }
   }
   return nextIterationElementInQueue;
 }

 /**
  *  @return An array of accessible children of the given @c element as reported by the selector
  *          -[NSObject(UIAccessibility) accessibilityElements].
  */
 - (NSArray *)gtx_accessibilityElementsOfElement:(id)element {
   if ([element respondsToSelector:@selector(accessibilityElements)]) {
     return [element accessibilityElements];
   }
   return nil;
 }

 /**
  *  @return An array of accessible children of the given @c element as reported by the selector
  *          -[NSObject(UIAccessibility) accessibilityElementAtIndex:].
  */
 - (NSArray *)gtx_accessibilityElementsFromIndicesOfElement:(id)element {
   NSMutableArray *axElementsFromIndices;
   if ([element respondsToSelector:@selector(accessibilityElementAtIndex:)] &&
       [element respondsToSelector:@selector(accessibilityElementCount)]) {
     NSInteger childrenCount = [element accessibilityElementCount];
     // This is a workaround to deal with UIKit classes that are reporting incorrect
     // accessibilityElementCount, see kAccessibilityChildrenUpperBound.
     if (childrenCount > 0 && childrenCount < kAccessibilityChildrenUpperBound) {
       axElementsFromIndices = [[NSMutableArray alloc] initWithCapacity:(NSUInteger)childrenCount];
       for (NSInteger index = 0; index < childrenCount; index++) {
         [axElementsFromIndices addObject:[element accessibilityElementAtIndex:index]];
       }
     }
   }
   return axElementsFromIndices;
 }

 /**
  *  Elements are hidden from accessibility trees
  *
  *  @return @c YES if the element is hidden from accessibility tree @c NO otherwise.
  */
 - (BOOL)gtx_isAccessibilityHiddenElement:(id)element {
   BOOL isHidden = NO;
   BOOL isAccessibilityHidden = NO;
   BOOL isHiddenDueToAccessibilityFrame = NO;
   BOOL isHiddenDueToFrame = NO;
   if ([element respondsToSelector:@selector(isHidden)]) {
     isHidden = [element isHidden];
   }
   if ([element respondsToSelector:@selector(accessibilityElementsHidden)]) {
     isAccessibilityHidden = [element accessibilityElementsHidden];
   }
   if ([element respondsToSelector:@selector(accessibilityFrame)]) {
     CGRect accessibilityFrame = [element accessibilityFrame];
     isHiddenDueToAccessibilityFrame =
         (accessibilityFrame.size.width == 0 || accessibilityFrame.size.height == 0);
   }
   if ([element respondsToSelector:@selector(frame)]) {
     CGRect frame = [element frame];
     isHiddenDueToFrame = frame.size.width == 0 || frame.size.height == 0;
   }
   return (isHidden || isAccessibilityHidden ||
           (isHiddenDueToFrame && isHiddenDueToAccessibilityFrame) ||
           [self gtx_isElementOffscreenPickerViewElement:element]);
 }

 /**
  * Determines if the element represents an accessibility element in a @c UIPickerTableView, and the
  * element is offscreen.
  *
  * @param element The accessibility element to check.
  * @return @c YES if the element is an offscreen accessibility element whose container is a
  *  @c UIPickerTableView, @c NO otherwise.
  */
 - (BOOL)gtx_isElementOffscreenPickerViewElement:(id)element {
   if (![element respondsToSelector:@selector(accessibilityFrame)] ||
       ![element respondsToSelector:@selector(accessibilityContainer)]) {
     return NO;
   }
   id accessibilityContainer = [element accessibilityContainer];
   if ([accessibilityContainer isKindOfClass:NSClassFromString(kUIPickerTableViewClassName)] &&
       [element isKindOfClass:NSClassFromString(kUIPickerTableViewAccessibilityElementClassName)]) {
     CGRect containerAccessibilityFrame = [accessibilityContainer accessibilityFrame];
     CGRect childAccessibilityFrame = [element accessibilityFrame];
     if (!CGRectIntersectsRect(childAccessibilityFrame, containerAccessibilityFrame)) {
       return YES;
     }
   }
   return NO;
 }

 @end
	//
	// Copyright 2018 Google Inc.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.
	//

	#import <UIKit/UIKit.h>

	#import "GTXAccessibilityTree.h"

	#import "GTXAssertions.h"
	#import "GTXTreeIteratorContext.h"

	/**
	* There seems to be errors in accessibility children reported by some UIKit classes especially
	* UITextEffectsWindow which reports 9223372036854775807 possibly due to internal type conversions
	* with -1, we use this bounds value to detect that case..
	*/
	static const NSInteger kAccessibilityChildrenUpperBound = 50000;

	/**
	* The class name for @c UIPickerTableView elements. Must be accessed via @c NSClassFromString
	* because it is a private class.
	*/
	static NSString *const kUIPickerTableViewClassName = @"UIPickerTableView";

	/**
	* The class name for accessibility children of @c UIPickerTableView elements. Must be accessed via
	* @c NSClassFromString because it is a private class.
	*/
	static NSString *const kUIPickerTableViewAccessibilityElementClassName =
	@"UITableViewCellAccessibilityElement";

	@implementation GTXAccessibilityTree {
	// Context for this object's NSEnumerator.
	GTXTreeIteratorContext *_enumeratorContext;

	// Root elements that this object handles.
	NSArray *_rootElements;
	}

	- (instancetype)initWithRootElements:(NSArray *)rootElements {
	self = [super init];
	if (self) {
	for (id element in rootElements) {
	if ([element isKindOfClass:[UIViewController class]]) {
	GTX_ASSERT(NO,
	@"Invalid root element %@ found. Check GTXToolkit docs to learn more about "
	@"valid root elements. Did you mean to use the .view property instead?",
	element);
	}
	}

	_enumeratorContext = [[GTXTreeIteratorContext alloc] initWithElements:rootElements];
	_rootElements = rootElements;
	}
	return self;
	}

	- (void)iterateAllElementsWithBlock:(GTXTreeIterationBlock)block {
	// Create a new tree object for iteration since the current object may be in the middle of a
	// for-in loop.
	GTXAccessibilityTree *tree = [[GTXAccessibilityTree alloc] initWithRootElements:_rootElements];
	GTXTreeIteratorElement *iteratorElement;
	while ((iteratorElement = [tree gtx_nextObject])) {
	block(iteratorElement);
	}
	}

	#pragma mark - NSEnumerator

	- (id)nextObject {
	id nextObject = [self gtx_nextObject].current;
	if (!nextObject) {
	// Allow the tree object to be re-enumerated once through.
	_enumeratorContext = [[GTXTreeIteratorContext alloc] initWithElements:_rootElements];
	}
	return nextObject;
	}

	#pragma mark - NSExtendedEnumerator

	- (NSArray *)allObjects {
	NSMutableArray *allObjects = [[NSMutableArray alloc] init];
	[self iterateAllElementsWithBlock:^(GTXTreeIteratorElement *_Nonnull iteratorElement) {
	[allObjects addObject:iteratorElement.current];
	}];
	return allObjects;
	}

	#pragma mark - Private

	/**
	* @return The next @c GTXTreeIteratorElement for the current @c GTXTreeIteratorContext.
	*/
	- (GTXTreeIteratorElement *)gtx_nextObject {
	if (![_enumeratorContext hasElementsInQueue]) {
	return nil;
	}

	id nextInQueue;
	GTXTreeIteratorElement *nextIterationElementInQueue;
	// Get the next "unvisited" element.
	do {
	GTXTreeIteratorElement *nextIterationElementCandidate = [_enumeratorContext peekNextElement];
	id nextCandidate = nextIterationElementCandidate.current;
	[_enumeratorContext dequeueNextElement];
	if (![_enumeratorContext didVisitElement:nextCandidate]) {
	if (![self gtx_isAccessibilityHiddenElement:nextCandidate]) {
	nextInQueue = nextCandidate;
	nextIterationElementInQueue = nextIterationElementCandidate;
	}
	}
	} while ([_enumeratorContext hasElementsInQueue] && !nextInQueue);
	if (!nextInQueue) {
	return nil;
	}
	[_enumeratorContext visitElement:nextInQueue];
	if ([nextInQueue respondsToSelector:@selector(isAccessibilityElement)]) {
	if (![nextInQueue isAccessibilityElement]) {
	// nextInQueue could be an accessibility container, if so enqueue its children.
	// There are two ways of getting the children of an accessibility container:
	// First, using @selector(accessibilityElements)
	NSArray *axElements = [self gtx_accessibilityElementsOfElement:nextInQueue];

	// Second, using @selector(accessibilityElementAtIndex:)
	NSArray *axElementsFromIndices =
	[self gtx_accessibilityElementsFromIndicesOfElement:nextInQueue];

	// Ensure that either the children are available only through one method or elements via both
	// are the same. Otherwise we must fail as the the accessibility tree is inconsistent.
	if (axElements && axElementsFromIndices) {
	NSSet *accessibilityElementsSet = [NSSet setWithArray:axElements];
	NSSet *accessibilityElementsFromIndicesSet = [NSSet setWithArray:axElementsFromIndices];
	NSAssert([accessibilityElementsSet isEqualToSet:accessibilityElementsFromIndicesSet],
	@"Accessibility elements obtained from -accessibilityElements and"
	@" -accessibilityElementAtIndex: are different - they must not be. Either provide"
	@" elements via one method or provide the same elements.\nDetails:\nElements via"
	@" accessibilityElements:%@\nElements via accessibilityElementAtIndex:\n"
	@"accessibilityElementCount:%@\nElements:%@",
	accessibilityElementsSet, @([nextInQueue accessibilityElementCount]),
	accessibilityElementsFromIndicesSet);

	// Ensure accessibilityElements* are marked as used even if NSAssert is removed.
	(void)accessibilityElementsSet;
	(void)accessibilityElementsFromIndicesSet;
	} else {
	// Set accessibilityElements to whichever is non nil or leave it as is.
	axElements = axElementsFromIndices ? axElementsFromIndices : axElements;
	}
	if (![nextInQueue respondsToSelector:@selector(accessibilityElementsHidden)] \|\|
	![nextInQueue accessibilityElementsHidden]) {
	for (id element in axElements) {
	if (![_enumeratorContext didVisitElement:element]) {
	[_enumeratorContext
	queueElement:[[GTXTreeIteratorElement alloc] initWithElement:element
	inContainer:nextInQueue]];
	}
	}
	}

	// nextInQueue could be a UIView subclass, if so enqueue its subviews.
	NSArray *subViews;
	if ([nextInQueue isKindOfClass:[UITableViewCell class]] \|\|
	[nextInQueue isKindOfClass:[UICollectionViewCell class]]) {
	subViews = [nextInQueue contentView].subviews;
	} else if ([nextInQueue respondsToSelector:@selector(subviews)]) {
	subViews = [nextInQueue subviews];
	}
	if ([nextInQueue respondsToSelector:@selector(isHidden)] && ![nextInQueue isHidden]) {
	for (id child in subViews) {
	if (![_enumeratorContext didVisitElement:child]) {
	[_enumeratorContext
	queueElement:[[GTXTreeIteratorElement alloc] initWithElement:child
	inContainer:nextInQueue]];
	}
	}
	}
	}
	}
	return nextIterationElementInQueue;
	}

	/**
	* @return An array of accessible children of the given @c element as reported by the selector
	* -[NSObject(UIAccessibility) accessibilityElements].
	*/
	- (NSArray *)gtx_accessibilityElementsOfElement:(id)element {
	if ([element respondsToSelector:@selector(accessibilityElements)]) {
	return [element accessibilityElements];
	}
	return nil;
	}

	/**
	* @return An array of accessible children of the given @c element as reported by the selector
	* -[NSObject(UIAccessibility) accessibilityElementAtIndex:].
	*/
	- (NSArray *)gtx_accessibilityElementsFromIndicesOfElement:(id)element {
	NSMutableArray *axElementsFromIndices;
	if ([element respondsToSelector:@selector(accessibilityElementAtIndex:)] &&
	[element respondsToSelector:@selector(accessibilityElementCount)]) {
	NSInteger childrenCount = [element accessibilityElementCount];
	// This is a workaround to deal with UIKit classes that are reporting incorrect
	// accessibilityElementCount, see kAccessibilityChildrenUpperBound.
	if (childrenCount > 0 && childrenCount < kAccessibilityChildrenUpperBound) {
	axElementsFromIndices = [[NSMutableArray alloc] initWithCapacity:(NSUInteger)childrenCount];
	for (NSInteger index = 0; index < childrenCount; index++) {
	[axElementsFromIndices addObject:[element accessibilityElementAtIndex:index]];
	}
	}
	}
	return axElementsFromIndices;
	}

	/**
	* Elements are hidden from accessibility trees
	*
	* @return @c YES if the element is hidden from accessibility tree @c NO otherwise.
	*/
	- (BOOL)gtx_isAccessibilityHiddenElement:(id)element {
	BOOL isHidden = NO;
	BOOL isAccessibilityHidden = NO;
	BOOL isHiddenDueToAccessibilityFrame = NO;
	BOOL isHiddenDueToFrame = NO;
	if ([element respondsToSelector:@selector(isHidden)]) {
	isHidden = [element isHidden];
	}
	if ([element respondsToSelector:@selector(accessibilityElementsHidden)]) {
	isAccessibilityHidden = [element accessibilityElementsHidden];
	}
	if ([element respondsToSelector:@selector(accessibilityFrame)]) {
	CGRect accessibilityFrame = [element accessibilityFrame];
	isHiddenDueToAccessibilityFrame =
	(accessibilityFrame.size.width == 0 \|\| accessibilityFrame.size.height == 0);
	}
	if ([element respondsToSelector:@selector(frame)]) {
	CGRect frame = [element frame];
	isHiddenDueToFrame = frame.size.width == 0 \|\| frame.size.height == 0;
	}
	return (isHidden \|\| isAccessibilityHidden \|\|
	(isHiddenDueToFrame && isHiddenDueToAccessibilityFrame) \|\|
	[self gtx_isElementOffscreenPickerViewElement:element]);
	}

	/**
	* Determines if the element represents an accessibility element in a @c UIPickerTableView, and the
	* element is offscreen.
	*
	* @param element The accessibility element to check.
	* @return @c YES if the element is an offscreen accessibility element whose container is a
	* @c UIPickerTableView, @c NO otherwise.
	*/
	- (BOOL)gtx_isElementOffscreenPickerViewElement:(id)element {
	if (![element respondsToSelector:@selector(accessibilityFrame)] \|\|
	![element respondsToSelector:@selector(accessibilityContainer)]) {
	return NO;
	}
	id accessibilityContainer = [element accessibilityContainer];
	if ([accessibilityContainer isKindOfClass:NSClassFromString(kUIPickerTableViewClassName)] &&
	[element isKindOfClass:NSClassFromString(kUIPickerTableViewAccessibilityElementClassName)]) {
	CGRect containerAccessibilityFrame = [accessibilityContainer accessibilityFrame];
	CGRect childAccessibilityFrame = [element accessibilityFrame];
	if (!CGRectIntersectsRect(childAccessibilityFrame, containerAccessibilityFrame)) {
	return YES;
	}
	}
	return NO;
	}

	@end