Summary:
This fixes a crash for the case when we try to drop a view that has already been dropped.
**The Problem**
We got reports of a crash (t12912526) that occurs when the resolveViewManager method can't resolve a ViewManager for a View being dropped.
Investigating this, one thing in common between all the stack traces for this is that dropView is called from line 210 of FlatNativeViewHierarchyManager. This part of the code is specifically the part we added to remove strong references to any clipped children (from views that have subview clipping enabled).
So this is a problem specifically with Nodes and clipSubviews, which brings up some questions:
**when can this happen?**
The only situation this can possibly happen is when we drop a child (which is clipped) followed by dropping its parent in the same cycle. Consider a tree where each view only has one child, such as: A - B - C - D. This crash would happen if D is clipped, and we removed it, followed by removing any of its parents in the same frame.
**if the removes happen in different frames, does this bug occur?**
No - the reason is that before we execute the DropView operations, we run through StateBuilder, which traverses the shadow tree and marks updates, thus removing the view going away (such that the delete in the next frame doesn't try to re-delete it).
So why doesn't this happen when we're dropping in the same frame? The reason is that manageChildren (where this all starts) asks to remove some views. We handle this by removing said Nodes and their children from the shadow tree. Consequently, when StateBuilder iterates over the shadow tree, it can't do the right thing because said nodes no longer exist.
As a more concrete example, consider A - B - C - D again, and consider that both D and B are removed. StateBuilder only sees A, and realizes that it now has 0 children (whereas before it has 1), so it removes B from its children. However, this process isn't recursive, so C never gets cleaned up.
**why doesn't this happen with Nodes without clipping containers?**
The answer to this is that NativeViewHierarchyManager's dropView method checks the existance of each child before deeply dropping that child and its subtree. So in this case, we drop D and all its children, and when we come to drop B, we try to drop C (which exists) and then its children (D, which doesn't exist because we already dropped it, so we ignore it).
**why doesn't this happen with non-Nodes?**
The reason is that non-Nodes handles removes differently - every remove is enqueued in a call to NativeViewHierarchy's manageChildren, which explicitly asks the parent to remove said child. Consequently, we never try to remove a child that is already removed.
**Fix**
The initial fix was to check whether or not the view exists, but this updated patch just does the right thing at drop time - i.e. whenever a view is dropped, we notify the parent of this fact so that it can clear the reference from clipped views.
**One last Note**
There are two reasons for switching `super.dropView` to `dropView` - first, the comment is only partially correct - calling `super.dropView` will avoid looking at clipped children (as an aside, that could cause a leak in the case of nested clipping subviews), but will look at clipped grandchildren, because of the super class's iteration across the set of children.
Reviewed By: astreet
Differential Revision: D3815485
Summary:
We were always getting LEFT explicitly, and, due to RTL support, we
should be asking for START instead.
Reviewed By: sriramramani
Differential Revision: D3836816
Summary:
This is minor, but for our use case a SparseArray is going to be faster as long as we have less than 10,000 clipped subviews, and will also use much less memory.
Faster because of the boxing, unboxing and hash caching; less memory as it is two arrays instead of the object overhead of the HashMap.
Reviewed By: ahmedre
Differential Revision: D3704326
Summary: This optimizes node region searches in clipping cases, and does position calculation for drawCommands off of the UI thread.
Reviewed By: ahmedre
Differential Revision: D3665301
Summary: @public Make UIOperation public so that custom implementations can expose instances of it.
Reviewed By: ahmedre
Differential Revision: D3618197
Summary:
Groups encountered a pretty major crash where, in many cases,
we would find that DrawCommands and Views were out of sync. This
turns out to be due to the fact that when we drop views from the
root view, we remove each child using removeChildAt (which ultimately
causes an invalidate and redraw). If this happens for a
FlatViewGroup, this causes issues where the Views are all removed,
but there are some DrawCommands (potentially DrawViews) that aren't
removed, hence them going out of sync.
Reviewed By: astreet
Differential Revision: D3473916
Summary: Currently only FlatViewGroup children were clipped, rather than all offscreen Android views.
Reviewed By: ahmedre
Differential Revision: D3462002
Summary:
Historically, removeClippedSubviews for Nodes would not clip views
that overflowed their parent. This patch changes that, so that Nodes can
properly clip views when they are off screen (even if they have descendants
that overflow the bounds of their parent).
This is done by calculating a set of offsets from the actual width and
height of the view, and using those in the clipping calculations.
Reviewed By: sriramramani
Differential Revision: D3409859
Summary:
The removeClippedSubviews optimization often detaches views while
maintaining strong references to them (so they can be attached again later
on). However, when removing the parent view, any detached views end up not
being cleaned up or removed, thus leaking memory. This fixes this by
explicitly dropping detached views when the parent is removed.
Reviewed By: astreet
Differential Revision: D3337513
Summary:
As of D3235050, Nodes supports the optimization of removing clipped
subviews from the hierarchy. However, because Nodes supports overflow:visible,
this could cause issues when DrawCommands overflow the bounds of their parent
container. This patch fixes this by not clipping any overflowing Nodes.
Reviewed By: astreet
Differential Revision: D3235072
Summary:
Nodes create a FlatViewGroup for a root node element, and NativeViewHierarchyManager assigns it an id that matches root node it. Now this top-level FlatViewGroup is added to a ReactRootView. In non-nodes, this ReactRootView has an id that matches root View id, and when this ReactRootView gets detached from Window, it sends an event to NativeViewHierarchyManager that says that all the children of this View must be removed recursively. This works great in non-Nodes, but fails in Nodes because ReactRootView has no id (-1) and NativeViewHierarchyManager fails to find a corresponding ReactShadowNode, throwing an Exception. To fix the issue and make it work again we need to assign this View id of the top level shadow node. This creates a minor issue, where 2 Views (ReactRootView and its only child) share the same id, but that is not a problem because we don't enforce uniqueness of the ids, and don't rely on getViewById().
This was originally implemented, but then I removed it because I thought it wasn't truly needed. Turns out, it is needed.
Reviewed By: sriramramani
Differential Revision: D2873995
Summary:
There is currently a bug where we never release any Views that no longer display, still storing hard references in NativeViewHierarchyManager. This diff is fixing this bug, and here is how:
a) there is already logic in place to drop FlatShadowNodes (UIImplementation.removeShadowNode).
b) there is already logic in place to drop Views (NativeViewHierarchyManager.dropView(int reactTag) - used to private but needs to be protected so I can call it)
c) (the missing part) when we are about to drop a FlatShadowNode, check if it mount to a View (i.e. there is a View associated with that node), put it into a ArrayList. When we finished updates to a nodes hierarchy (which happens in non-UI thread), collect ids from those nodes and enqueue a UIOperation that will drop all the Views. We can either forward nodes as FlatShadowNode[], or only ids as int[]. Both should be fine, but as a rule of thumb we don't touch shadow node hierarchy from UI thread (as we don't touch Views from non-UI thread) so passing int[] is what this code is doing.
Reviewed By: ahmedre
Differential Revision: D2757310
Summary: Any padding that a FlatShadowNode is assigned by React runtime should be translated to a backing Android View so it looks correct and lays out children accordingly.
Reviewed By: sriramramani
Differential Revision: D2756562
Summary: This diff adds an `AndroidView` as a proxy for custom Views in FlatUIImplementation. Any ReactShadowNode that FlatUIImplementation doesn't recognize (because they don't extend from FlatShadowNode) will be wrapped with AndroidView to ensure that it measures and displays correctly. While not perfect, this is the easiest way to support custom Views (EditTexts, DrawerLayouts, ScrollViews etc).
Reviewed By: ahmedre
Differential Revision: D2751716
Summary: @public When Android dispatches `MotionEvent` to `ReactRootView`, it needs to find a correspoding react node that should receive it. To be able to do it, we need to store boundaries of every `FlatShadowNode` in `FlatViewGroup`. Then we can iterate over node boundaries and find one that contains the touch event coordinates.
Reviewed By: sriramramani
Differential Revision: D2694197
Summary: @public This diff adds a `FlatShadowNode.forceMountToView()` method that will render its contents in it own `View`.
Reviewed By: sriramramani
Differential Revision: D2564502
Summary: @public This patch adds basic support for RCTImageView (only 'src', 'tintColor' and 'resizeMode' properties are supported for now), and a concept of AttachDetachListener that is required to support it to FlatUIImplementations.
Reviewed By: sriramramani
Differential Revision: D2564389
Summary: @public Initial version of FlatUIImplementation lacks any primitives support (such as RCTText, RCTImageView or RCTView). This diff add the first part, RCTText (alongside with RCTVirtualText and RCTRawText).
Reviewed By: sriramramani
Differential Revision: D2693348
