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Layout child sliver only when expanded #4

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Layout child sliver only when expanded #4

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55 changes: 32 additions & 23 deletions lib/src/rendering/render_sliver_expandable.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -135,27 +135,34 @@ class RenderSliverExpandable extends RenderSliver with RenderSliverHelpers {
calculatePaintOffset(constraints, from: 0, to: resolvedHeaderExtent);
final headerCacheExtent =
calculateCacheOffset(constraints, from: 0, to: resolvedHeaderExtent);
sliver!.layout(
constraints.copyWith(
scrollOffset:
math.max(0, constraints.scrollOffset - resolvedHeaderExtent),
cacheOrigin:
math.min(0, constraints.cacheOrigin + resolvedHeaderExtent),
remainingPaintExtent:
math.max(0, constraints.remainingPaintExtent - headerPaintExtent),
remainingCacheExtent:
math.max(0, constraints.remainingCacheExtent - headerCacheExtent),
overlap: math.max(0, constraints.overlap - resolvedHeaderExtent),
precedingScrollExtent:
constraints.precedingScrollExtent + resolvedHeaderExtent,
),
parentUsesSize: true,
);
final sliverGeometry = sliver!.geometry!;
if (sliverGeometry.scrollOffsetCorrection != null) {
geometry = SliverGeometry(
scrollOffsetCorrection: sliverGeometry.scrollOffsetCorrection);
return;

final SliverGeometry sliverGeometry;

if (animation.value > 0) {
sliver!.layout(
constraints.copyWith(
scrollOffset:
math.max(0, constraints.scrollOffset - resolvedHeaderExtent),
cacheOrigin:
math.min(0, constraints.cacheOrigin + resolvedHeaderExtent),
remainingPaintExtent:
math.max(0, constraints.remainingPaintExtent - headerPaintExtent),
remainingCacheExtent:
math.max(0, constraints.remainingCacheExtent - headerCacheExtent),
overlap: math.max(0, constraints.overlap - resolvedHeaderExtent),
precedingScrollExtent:
constraints.precedingScrollExtent + resolvedHeaderExtent,
),
parentUsesSize: true,
);
sliverGeometry = sliver!.geometry!;
if (sliverGeometry.scrollOffsetCorrection != null) {
geometry = SliverGeometry(
scrollOffsetCorrection: sliverGeometry.scrollOffsetCorrection);
return;
}
} else {
sliverGeometry = const SliverGeometry();
}

final paintExtent = math.min(
Expand Down Expand Up @@ -225,8 +232,8 @@ class RenderSliverExpandable extends RenderSliver with RenderSliverHelpers {

@override
void paint(PaintingContext context, Offset offset) {
assert(sliver != null);
if (geometry!.visible) {
assert(sliver != null);
if (header != null) {
context.paintChild(
header!, offset + getChildParentData(header!).paintOffset);
Expand Down Expand Up @@ -255,8 +262,10 @@ class RenderSliverExpandable extends RenderSliver with RenderSliverHelpers {

bool get isSliverVisible {
assert(sliver != null);
assert(sliver!.geometry != null);

if (sliver!.geometry == null) {
return false;
}
return animation.value > 0 && sliver!.geometry!.visible;
}

Expand Down