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Allow UIView subviews to be a part of Accessibility Tree #2111

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Allow UIView subviews to be a part of Accessibility Tree #2111

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35 changes: 35 additions & 0 deletions Source/Details/_ASDisplayViewAccessiblity.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -220,6 +220,11 @@ static BOOL nodeIsHiddenFromAcessibility(ASDisplayNode *node) {
return node.isHidden || node.alpha == 0.0 || node.accessibilityElementsHidden;
}

/// returns YES if this view should be considered "hidden" from the screen reader.
static BOOL viewIsHiddenFromAcessibility(UIView *view) {
return view.isHidden || view.alpha == 0.0 || view.accessibilityElementsHidden;
}

/// Collect all accessibliity elements for a given view and view node
static void CollectAccessibilityElements(ASDisplayNode *node, NSMutableArray *elements)
{
Expand Down Expand Up @@ -302,6 +307,36 @@ static void CollectAccessibilityElements(ASDisplayNode *node, NSMutableArray *el
[elements addObject:subnode.view];
}
}

if (modalSubnode) {
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This is a long complicated method. It is quite possible that in the future someone will add to it, likely at the end of the method. This early return could cause newly added logic to be skipped. To protect against that, I'd prefer you put your logic inside of an if and not early return:

if (!modalSubnode) {
   // your logic
    ....
}

return;
}

NSArray *subviews = view.subviews;
for (UIView *subview in subviews) {
// If a view is is already added then skip it
if ([elements containsObject:subview]) {
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We are looping over subviews and elements for each subview. It would be more efficient to put the elements in a set so lookup is O(1), or use a smart diff algorithm to get only the subviews not in elements and iterate over those.

[elements containsObject:subview] is likely the most expensive operation in this loop, so it should at the very least be moved to the last possible check. e.g.,

if ((subview.isAccessibilityElement || subview.accessibilityElementCount > 0)) && ! [elements containsObject:subview]) {
      [elements addObject:subview];
}

continue;
}

// If a view is hidden or has an alpha of 0.0 we should not include it
if (viewIsHiddenFromAcessibility(subview)) {
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This is cheaper than iterating over elements and should be done first.

continue;
}

// If a subview is outside of the view's window, exclude it UNLESS it is a subview of an UIScrollView.
// In this case UIKit will return the element even if it is outside of the window or the scrollView's visible rect (contentOffset + contentSize)
CGRect viewInWindowCoords = [node convertRect:subview.frame toNode:nil];
if (!CGRectIntersectsRect(view.window.frame, viewInWindowCoords) && !recusivelyCheckSuperviewsForScrollView(view)) {
continue;
}

if (subview.isAccessibilityElement) {
[elements addObject:subview];
} else if (subview.accessibilityElementCount > 0) {
[elements addObject:subview];
}
}
}

@implementation _ASDisplayView (UIAccessibilityContainer)
Expand Down