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Add support for listening to pin / unpin events #97

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Add support for listening to pin / unpin events #97

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281 changes: 157 additions & 124 deletions lib/src/rendering/sliver_sticky_header.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ import 'dart:math' as math;

import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/scheduler.dart';
import 'package:flutter_sticky_header/flutter_sticky_header.dart';
import 'package:value_layout_builder/value_layout_builder.dart';

Expand All @@ -10,43 +11,45 @@ import 'package:value_layout_builder/value_layout_builder.dart';
/// The [header] stays pinned when it hits the start of the viewport until
/// the [child] scrolls off the viewport.
class RenderSliverStickyHeader extends RenderSliver with RenderSliverHelpers {
SliverStickyHeaderState? _oldState;

SliverStickyHeaderActivityHandler? activityHandler;
SliverStickyHeaderActivity? _lastReportedActivity;

double? _headerExtent;
late bool _isPinned;
bool _overlapsContent;

bool _sticky;
StickyHeaderController? _controller;

RenderBox? _header;

RenderSliver? _child;
RenderSliverStickyHeader({
RenderObject? header,
RenderSliver? child,
bool overlapsContent: false,
bool sticky: true,
bool overlapsContent = false,
bool sticky = true,
StickyHeaderController? controller,
this.activityHandler,
}) : _overlapsContent = overlapsContent,
_sticky = sticky,
_controller = controller {
this.header = header as RenderBox?;
this.child = child;
}

SliverStickyHeaderState? _oldState;
double? _headerExtent;
late bool _isPinned;

bool get overlapsContent => _overlapsContent;
bool _overlapsContent;

set overlapsContent(bool value) {
if (_overlapsContent == value) return;
_overlapsContent = value;
markNeedsLayout();
}

bool get sticky => _sticky;
bool _sticky;
/// The render object's unique child
RenderSliver? get child => _child;

set sticky(bool value) {
if (_sticky == value) return;
_sticky = value;
markNeedsLayout();
set child(RenderSliver? value) {
if (_child != null) dropChild(_child!);
_child = value;
if (_child != null) adoptChild(_child!);
}

StickyHeaderController? get controller => _controller;
StickyHeaderController? _controller;

set controller(StickyHeaderController? value) {
if (_controller == value) return;
Expand All @@ -59,28 +62,34 @@ class RenderSliverStickyHeader extends RenderSliver with RenderSliverHelpers {

/// The render object's header
RenderBox? get header => _header;
RenderBox? _header;

set header(RenderBox? value) {
if (_header != null) dropChild(_header!);
_header = value;
if (_header != null) adoptChild(_header!);
}

/// The render object's unique child
RenderSliver? get child => _child;
RenderSliver? _child;
double? get headerLogicalExtent => overlapsContent ? 0.0 : _headerExtent;

set child(RenderSliver? value) {
if (_child != null) dropChild(_child!);
_child = value;
if (_child != null) adoptChild(_child!);
bool get overlapsContent => _overlapsContent;
set overlapsContent(bool value) {
if (_overlapsContent == value) return;
_overlapsContent = value;
markNeedsLayout();
}

bool get sticky => _sticky;

set sticky(bool value) {
if (_sticky == value) return;
_sticky = value;
markNeedsLayout();
}

@override
void setupParentData(RenderObject child) {
if (child.parentData is! SliverPhysicalParentData)
child.parentData = SliverPhysicalParentData();
void applyPaintTransform(RenderObject child, Matrix4 transform) {
final SliverPhysicalParentData childParentData =
child.parentData as SliverPhysicalParentData;
childParentData.applyPaintTransform(transform);
}

@override
Expand All @@ -91,22 +100,36 @@ class RenderSliverStickyHeader extends RenderSliver with RenderSliverHelpers {
}

@override
void detach() {
super.detach();
if (_header != null) _header!.detach();
if (_child != null) _child!.detach();
double childMainAxisPosition(RenderObject? child) {
if (child == header)
return _isPinned
? 0.0
: -(constraints.scrollOffset + constraints.overlap);
if (child == this.child)
return calculatePaintOffset(constraints,
from: 0.0, to: headerLogicalExtent!);
return 0;
}

@override
void redepthChildren() {
if (_header != null) redepthChild(_header!);
if (_child != null) redepthChild(_child!);
double? childScrollOffset(RenderObject child) {
assert(child.parent == this);
if (child == this.child) {
return _headerExtent;
} else {
return super.childScrollOffset(child);
}
}

@override
void visitChildren(RenderObjectVisitor visitor) {
if (_header != null) visitor(_header!);
if (_child != null) visitor(_child!);
double computeHeaderExtent() {
if (header == null) return 0.0;
assert(header!.hasSize);
switch (constraints.axis) {
case Axis.vertical:
return header!.size.height;
case Axis.horizontal:
return header!.size.width;
}
}

@override
Expand All @@ -121,18 +144,69 @@ class RenderSliverStickyHeader extends RenderSliver with RenderSliverHelpers {
return result;
}

double computeHeaderExtent() {
if (header == null) return 0.0;
assert(header!.hasSize);
switch (constraints.axis) {
case Axis.vertical:
return header!.size.height;
case Axis.horizontal:
return header!.size.width;
@override
void detach() {
super.detach();
if (_header != null) _header!.detach();
if (_child != null) _child!.detach();
}

@override
bool hitTestChildren(SliverHitTestResult result,
{required double mainAxisPosition, required double crossAxisPosition}) {
assert(geometry!.hitTestExtent > 0.0);
final double childScrollExtent = child?.geometry?.scrollExtent ?? 0.0;
final double headerPosition = sticky
? math.min(
constraints.overlap,
childScrollExtent -
constraints.scrollOffset -
(overlapsContent ? _headerExtent! : 0.0))
: -constraints.scrollOffset;

if (header != null &&
(mainAxisPosition - headerPosition) <= _headerExtent!) {
final didHitHeader = hitTestBoxChild(
BoxHitTestResult.wrap(SliverHitTestResult.wrap(result)),
header!,
mainAxisPosition:
mainAxisPosition - childMainAxisPosition(header) - headerPosition,
crossAxisPosition: crossAxisPosition,
);

return didHitHeader ||
(_overlapsContent &&
child != null &&
child!.geometry!.hitTestExtent > 0.0 &&
child!.hitTest(result,
mainAxisPosition:
mainAxisPosition - childMainAxisPosition(child),
crossAxisPosition: crossAxisPosition));
} else if (child != null && child!.geometry!.hitTestExtent > 0.0) {
return child!.hitTest(result,
mainAxisPosition: mainAxisPosition - childMainAxisPosition(child),
crossAxisPosition: crossAxisPosition);
}
return false;
}

double? get headerLogicalExtent => overlapsContent ? 0.0 : _headerExtent;
@override
void paint(PaintingContext context, Offset offset) {
if (geometry!.visible) {
if (child != null && child!.geometry!.visible) {
final SliverPhysicalParentData childParentData =
child!.parentData as SliverPhysicalParentData;
context.paintChild(child!, offset + childParentData.paintOffset);
}

// The header must be drawn over the sliver.
if (header != null) {
final SliverPhysicalParentData headerParentData =
header!.parentData as SliverPhysicalParentData;
context.paintChild(header!, offset + headerParentData.paintOffset);
}
}
}

@override
void performLayout() {
Expand Down Expand Up @@ -261,6 +335,8 @@ class RenderSliverStickyHeader extends RenderSliver with RenderSliverHelpers {
controller?.stickyHeaderScrollOffset =
constraints.precedingScrollExtent;
}
_updateActivity(headerScrollRatio);

// second layout if scroll percentage changed and header is a
// RenderStickyHeaderLayoutBuilder.
if (header is RenderConstrainedLayoutBuilder<
Expand Down Expand Up @@ -300,88 +376,45 @@ class RenderSliverStickyHeader extends RenderSliver with RenderSliverHelpers {
}
}

@override
bool hitTestChildren(SliverHitTestResult result,
{required double mainAxisPosition, required double crossAxisPosition}) {
assert(geometry!.hitTestExtent > 0.0);
final double childScrollExtent = child?.geometry?.scrollExtent ?? 0.0;
final double headerPosition = sticky
? math.min(
constraints.overlap,
childScrollExtent -
constraints.scrollOffset -
(overlapsContent ? _headerExtent! : 0.0))
: -constraints.scrollOffset;
void _updateActivity(double headerScrollRatio) {
final SliverStickyHeaderActivity activity;
if (!_isPinned) {
activity = SliverStickyHeaderActivity.unpinned;
} else if (headerScrollRatio >= 1.0) {
activity = SliverStickyHeaderActivity.pushed;
} else if (headerScrollRatio > 0.0) {
activity = SliverStickyHeaderActivity.settling;
} else {
activity = SliverStickyHeaderActivity.pinned;
}

if (header != null &&
(mainAxisPosition - headerPosition) <= _headerExtent!) {
final didHitHeader = hitTestBoxChild(
BoxHitTestResult.wrap(SliverHitTestResult.wrap(result)),
header!,
mainAxisPosition: mainAxisPosition - childMainAxisPosition(header) - headerPosition,
crossAxisPosition: crossAxisPosition,
if (activityHandler != null &&
_lastReportedActivity != null &&
activity != _lastReportedActivity) {
WidgetsBinding.instance.scheduleTask(
() => activityHandler?.call(activity),
Priority.touch,
);

return didHitHeader ||
(_overlapsContent &&
child != null &&
child!.geometry!.hitTestExtent > 0.0 &&
child!.hitTest(result,
mainAxisPosition:
mainAxisPosition - childMainAxisPosition(child),
crossAxisPosition: crossAxisPosition));
} else if (child != null && child!.geometry!.hitTestExtent > 0.0) {
return child!.hitTest(result,
mainAxisPosition: mainAxisPosition - childMainAxisPosition(child),
crossAxisPosition: crossAxisPosition);
}
return false;
}

@override
double childMainAxisPosition(RenderObject? child) {
if (child == header)
return _isPinned
? 0.0
: -(constraints.scrollOffset + constraints.overlap);
if (child == this.child)
return calculatePaintOffset(constraints,
from: 0.0, to: headerLogicalExtent!);
return 0;
_lastReportedActivity = activity;
}

@override
double? childScrollOffset(RenderObject child) {
assert(child.parent == this);
if (child == this.child) {
return _headerExtent;
} else {
return super.childScrollOffset(child);
}
void redepthChildren() {
if (_header != null) redepthChild(_header!);
if (_child != null) redepthChild(_child!);
}

@override
void applyPaintTransform(RenderObject child, Matrix4 transform) {
final SliverPhysicalParentData childParentData =
child.parentData as SliverPhysicalParentData;
childParentData.applyPaintTransform(transform);
void setupParentData(RenderObject child) {
if (child.parentData is! SliverPhysicalParentData)
child.parentData = SliverPhysicalParentData();
}

@override
void paint(PaintingContext context, Offset offset) {
if (geometry!.visible) {
if (child != null && child!.geometry!.visible) {
final SliverPhysicalParentData childParentData =
child!.parentData as SliverPhysicalParentData;
context.paintChild(child!, offset + childParentData.paintOffset);
}

// The header must be drawn over the sliver.
if (header != null) {
final SliverPhysicalParentData headerParentData =
header!.parentData as SliverPhysicalParentData;
context.paintChild(header!, offset + headerParentData.paintOffset);
}
}
void visitChildren(RenderObjectVisitor visitor) {
if (_header != null) visitor(_header!);
if (_child != null) visitor(_child!);
}
}
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