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enable more retained rendering opportunities for LeaderLayer (#96486)

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Michael Goderbauer 2022-01-11 18:20:14 -08:00 committed by GitHub
parent fe05239487
commit d290763941
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4 changed files with 71 additions and 116 deletions
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149
packages/flutter/lib/src/rendering/layer.dart
View file

@ -2109,6 +2109,8 @@ class PhysicalModelLayer extends ContainerLayer {
/// * [RenderLeaderLayer] and [RenderFollowerLayer], the corresponding
/// render objects.
class LayerLink {
/// The [LeaderLayer] connected to this link.
LeaderLayer? get leader => _leader;
LeaderLayer? _leader;
void _registerLeader(LeaderLayer leader) {
@ -2160,35 +2162,6 @@ class LayerLink {
}());
}
int _connectedFollowers = 0;
/// Whether a [LeaderLayer] is currently connected to this link.
bool get leaderConnected => _leader != null;
/// Called by the [FollowerLayer] to establish a link to a [LeaderLayer].
///
/// The returned [LayerLinkHandle] provides access to the leader via
/// [LayerLinkHandle.leader].
///
/// When the [FollowerLayer] no longer wants to follow the [LeaderLayer],
/// [LayerLinkHandle.dispose] must be called to disconnect the link.
_LayerLinkHandle _registerFollower() {
assert(_connectedFollowers >= 0);
_connectedFollowers++;
return _LayerLinkHandle(this);
}
/// Returns the [LeaderLayer] currently connected to this link.
///
/// Valid in debug mode only. Returns null in all other modes.
LeaderLayer? get debugLeader {
LeaderLayer? result;
if (kDebugMode) {
result = _leader;
}
return result;
}
/// The total size of the content of the connected [LeaderLayer].
///
/// Generally this should be set by the [RenderObject] that paints on the
@ -2201,30 +2174,6 @@ class LayerLink {
String toString() => '${describeIdentity(this)}(${ _leader != null ? "<linked>" : "<dangling>" })';
}
/// A handle provided by [LayerLink.registerFollower] to a calling
/// [FollowerLayer] to establish a link between that [FollowerLayer] and a
/// [LeaderLayer].
///
/// If the link is no longer needed, [dispose] must be called to disconnect it.
class _LayerLinkHandle {
_LayerLinkHandle(this._link);
LayerLink? _link;
/// The currently-registered [LeaderLayer], if any.
LeaderLayer? get leader => _link!._leader;
/// Disconnects the link between the [FollowerLayer] owning this handle and
/// the [leader].
///
/// The [LayerLinkHandle] becomes unusable after calling this method.
void dispose() {
assert(_link!._connectedFollowers > 0);
_link!._connectedFollowers--;
_link = null;
}
}
/// A composited layer that can be followed by a [FollowerLayer].
///
/// This layer collapses the accumulated offset into a transform and passes
@ -2279,41 +2228,18 @@ class LeaderLayer extends ContainerLayer {
}
}
/// {@macro flutter.rendering.FollowerLayer.alwaysNeedsAddToScene}
@override
bool get alwaysNeedsAddToScene => _link._connectedFollowers > 0;
@override
void attach(Object owner) {
super.attach(owner);
assert(_debugSetLastOffset(null));
_link._registerLeader(this);
}
@override
void detach() {
assert(_debugSetLastOffset(null));
_link._unregisterLeader(this);
super.detach();
}
/// The offset the last time this layer was composited.
///
/// This is reset to null when the layer is attached or detached, to help
/// catch cases where the follower layer ends up before the leader layer, but
/// not every case can be detected.
Offset? _debugLastOffset;
bool _debugSetLastOffset(Offset? offset) {
bool result = false;
assert(() {
_debugLastOffset = offset;
result = true;
return true;
}());
return result;
}
@override
bool findAnnotations<S extends Object>(AnnotationResult<S> result, Offset localPosition, { required bool onlyFirst }) {
return super.findAnnotations<S>(result, localPosition - offset, onlyFirst: onlyFirst);
@ -2322,7 +2248,6 @@ class LeaderLayer extends ContainerLayer {
@override
void addToScene(ui.SceneBuilder builder) {
assert(offset != null);
assert(_debugSetLastOffset(offset));
if (offset != Offset.zero)
engineLayer = builder.pushTransform(
Matrix4.translationValues(offset.dx, offset.dy, 0.0).storage,
@ -2386,10 +2311,6 @@ class FollowerLayer extends ContainerLayer {
LayerLink get link => _link;
set link(LayerLink value) {
assert(value != null);
if (value != _link && _leaderHandle != null) {
_leaderHandle!.dispose();
_leaderHandle = value._registerFollower();
}
_link = value;
}
LayerLink _link;
@ -2436,21 +2357,6 @@ class FollowerLayer extends ContainerLayer {
/// * [unlinkedOffset], for when the layer is not linked.
Offset? linkedOffset;
_LayerLinkHandle? _leaderHandle;
@override
void attach(Object owner) {
super.attach(owner);
_leaderHandle = _link._registerFollower();
}
@override
void detach() {
super.detach();
_leaderHandle?.dispose();
_leaderHandle = null;
}
Offset? _lastOffset;
Matrix4? _lastTransform;
Matrix4? _invertedTransform;
@ -2470,7 +2376,7 @@ class FollowerLayer extends ContainerLayer {
@override
bool findAnnotations<S extends Object>(AnnotationResult<S> result, Offset localPosition, { required bool onlyFirst }) {
if (_leaderHandle!.leader == null) {
if (_link.leader == null) {
if (showWhenUnlinked!) {
return super.findAnnotations(result, localPosition - unlinkedOffset!, onlyFirst: onlyFirst);
}
@ -2545,11 +2451,39 @@ class FollowerLayer extends ContainerLayer {
return _pathsToCommonAncestor(a.parent, b.parent, ancestorsA, ancestorsB);
}
bool _debugCheckLeaderBeforeFollower(
List<ContainerLayer> leaderToCommonAncestor,
List<ContainerLayer> followerToCommonAncestor,
) {
if (followerToCommonAncestor.length <= 1) {
// Follower is the common ancestor, ergo the leader must come AFTER the follower.
return false;
}
if (leaderToCommonAncestor.length <= 1) {
// Leader is the common ancestor, ergo the leader must come BEFORE the follower.
return true;
}
// Common ancestor is neither the leader nor the follower.
final ContainerLayer leaderSubtreeBelowAncestor = leaderToCommonAncestor[leaderToCommonAncestor.length - 2];
final ContainerLayer followerSubtreeBelowAncestor = followerToCommonAncestor[followerToCommonAncestor.length - 2];
Layer? sibling = leaderSubtreeBelowAncestor;
while (sibling != null) {
if (sibling == followerSubtreeBelowAncestor) {
return true;
}
sibling = sibling.nextSibling;
}
// The follower subtree didn't come after the leader subtree.
return false;
}
/// Populate [_lastTransform] given the current state of the tree.
void _establishTransform() {
assert(link != null);
_lastTransform = null;
final LeaderLayer? leader = _leaderHandle!.leader;
final LeaderLayer? leader = _link.leader;
// Check to see if we are linked.
if (leader == null)
return;
@ -2558,22 +2492,25 @@ class FollowerLayer extends ContainerLayer {
leader.owner == owner,
'Linked LeaderLayer anchor is not in the same layer tree as the FollowerLayer.',
);
assert(
leader._debugLastOffset != null,
'LeaderLayer anchor must come before FollowerLayer in paint order, but the reverse was true.',
);
// Stores [leader, ..., commonAncestor] after calling _pathsToCommonAncestor.
final List<ContainerLayer?> forwardLayers = <ContainerLayer>[leader];
final List<ContainerLayer> forwardLayers = <ContainerLayer>[leader];
// Stores [this (follower), ..., commonAncestor] after calling
// _pathsToCommonAncestor.
final List<ContainerLayer?> inverseLayers = <ContainerLayer>[this];
final List<ContainerLayer> inverseLayers = <ContainerLayer>[this];
final Layer? ancestor = _pathsToCommonAncestor(
leader, this,
forwardLayers, inverseLayers,
);
assert(ancestor != null);
assert(
ancestor != null,
'LeaderLayer and FollowerLayer do not have a common ancestor.',
);
assert(
_debugCheckLeaderBeforeFollower(forwardLayers, inverseLayers),
'LeaderLayer anchor must come before FollowerLayer in paint order, but the reverse was true.',
);
final Matrix4 forwardTransform = _collectTransformForLayerChain(forwardLayers);
// Further transforms the coordinate system to a hypothetical child (null)
@ -2611,7 +2548,7 @@ class FollowerLayer extends ContainerLayer {
void addToScene(ui.SceneBuilder builder) {
assert(link != null);
assert(showWhenUnlinked != null);
if (_leaderHandle!.leader == null && !showWhenUnlinked!) {
if (_link.leader == null && !showWhenUnlinked!) {
_lastTransform = null;
_lastOffset = null;
_inverseDirty = true;

6
packages/flutter/lib/src/rendering/proxy_box.dart
View file

@ -5289,7 +5289,7 @@ class RenderFollowerLayer extends RenderProxyBox {
@override
bool hitTest(BoxHitTestResult result, { required Offset position }) {
// Disables the hit testing if this render object is hidden.
if (!link.leaderConnected && !showWhenUnlinked)
if (link.leader == null && !showWhenUnlinked)
return false;
// RenderFollowerLayer objects don't check if they are
// themselves hit, because it's confusing to think about
@ -5313,8 +5313,8 @@ class RenderFollowerLayer extends RenderProxyBox {
void paint(PaintingContext context, Offset offset) {
final Size? leaderSize = link.leaderSize;
assert(
link.leaderSize != null || (!link.leaderConnected || leaderAnchor == Alignment.topLeft),
'$link: layer is linked to ${link.debugLeader} but a valid leaderSize is not set. '
link.leaderSize != null || (link.leader == null || leaderAnchor == Alignment.topLeft),
'$link: layer is linked to ${link.leader} but a valid leaderSize is not set. '
'leaderSize is required when leaderAnchor is not Alignment.topLeft '
'(current value is $leaderAnchor).',
);

14
packages/flutter/test/rendering/layers_test.dart
View file

@ -176,7 +176,7 @@ void main() {
expect(leaderLayer.link, link2);
});
test('leader layers are always dirty when connected to follower layer', () {
test('leader layers not dirty when connected to follower layer', () {
final ContainerLayer root = ContainerLayer()..attach(Object());
final LayerLink link = LayerLink();
@ -190,7 +190,7 @@ void main() {
followerLayer.debugMarkClean();
leaderLayer.updateSubtreeNeedsAddToScene();
followerLayer.updateSubtreeNeedsAddToScene();
expect(leaderLayer.debugSubtreeNeedsAddToScene, true);
expect(leaderLayer.debugSubtreeNeedsAddToScene, false);
});
test('leader layers are not dirty when all followers disconnects', () {
@ -204,24 +204,24 @@ void main() {
leaderLayer.updateSubtreeNeedsAddToScene();
expect(leaderLayer.debugSubtreeNeedsAddToScene, false);
// Connecting a follower requires adding to scene.
// Connecting a follower does not require adding to scene
final FollowerLayer follower1 = FollowerLayer(link: link);
root.append(follower1);
leaderLayer.debugMarkClean();
leaderLayer.updateSubtreeNeedsAddToScene();
expect(leaderLayer.debugSubtreeNeedsAddToScene, true);
expect(leaderLayer.debugSubtreeNeedsAddToScene, false);
final FollowerLayer follower2 = FollowerLayer(link: link);
root.append(follower2);
leaderLayer.debugMarkClean();
leaderLayer.updateSubtreeNeedsAddToScene();
expect(leaderLayer.debugSubtreeNeedsAddToScene, true);
expect(leaderLayer.debugSubtreeNeedsAddToScene, false);
// Disconnecting one follower, still needs add to scene.
// Disconnecting one follower, still does not needs add to scene.
follower2.remove();
leaderLayer.debugMarkClean();
leaderLayer.updateSubtreeNeedsAddToScene();
expect(leaderLayer.debugSubtreeNeedsAddToScene, true);
expect(leaderLayer.debugSubtreeNeedsAddToScene, false);
// Disconnecting all followers goes back to not requiring add to scene.
follower1.remove();

18
packages/flutter/test/widgets/composited_transform_test.dart
View file

@ -300,4 +300,22 @@ void main() {
}
}
});
testWidgets('Leader after Follower asserts', (WidgetTester tester) async {
final LayerLink link = LayerLink();
await tester.pumpWidget(
CompositedTransformFollower(
link: link,
child: CompositedTransformTarget(
link: link,
child: const SizedBox(height: 20, width: 20),
),
),
);
expect(
(tester.takeException() as AssertionError).message,
contains('LeaderLayer anchor must come before FollowerLayer in paint order'),
);
});
}