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Merge pull request #1772 from abarth/mixed_cleanup

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Cleanup MixedViewport
This commit is contained in:
Adam Barth
2016-02-10 23:33:59 -08:00
parent 3fa3d2266f fc23277df5
commit 75bc0277ff
2 changed files with 92 additions and 45 deletions
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91
packages/flutter/lib/src/widgets/mixed_viewport.dart
View File

@@ -103,7 +103,7 @@ class _MixedViewportElement extends RenderObjectElement<MixedViewport> {
/// Returns false if any of the previously-cached offsets have been marked as
/// invalid and need to be updated.
bool get isValid => _invalidIndices.length == 0;
bool get _isValid => _invalidIndices.isEmpty;
/// The constraints for which the current offsets are valid.
BoxConstraints _lastLayoutConstraints;
@@ -139,17 +139,20 @@ class _MixedViewportElement extends RenderObjectElement<MixedViewport> {
void mount(Element parent, dynamic newSlot) {
super.mount(parent, newSlot);
renderObject.callback = layout;
renderObject.totalExtentCallback = _noIntrinsicExtent;
renderObject.maxCrossAxisExtentCallback = _noIntrinsicExtent;
renderObject.minCrossAxisExtentCallback = _noIntrinsicExtent;
renderObject
..direction = widget.direction
..callback = layout
..totalExtentCallback = _noIntrinsicExtent
..maxCrossAxisExtentCallback = _noIntrinsicExtent
..minCrossAxisExtentCallback = _noIntrinsicExtent;
}
void unmount() {
renderObject.callback = null;
renderObject.totalExtentCallback = null;
renderObject.minCrossAxisExtentCallback = null;
renderObject.maxCrossAxisExtentCallback = null;
renderObject
..callback = null
..totalExtentCallback = null
..minCrossAxisExtentCallback = null
..maxCrossAxisExtentCallback = null;
super.unmount();
}
@@ -167,14 +170,15 @@ class _MixedViewportElement extends RenderObjectElement<MixedViewport> {
return null;
}
static const Object _omit = const Object(); // used as a slot when it's not yet time to attach the child
static final Object _omit = new Object(); // used as a slot when it's not yet time to attach the child
void update(MixedViewport newWidget) {
_ChangeDescription changes = newWidget.evaluateChangesFrom(widget);
super.update(newWidget);
renderObject.direction = widget.direction;
if (changes == _ChangeDescription.resized)
_resetCache();
if (changes != _ChangeDescription.none || !isValid) {
if (changes != _ChangeDescription.none || !_isValid) {
renderObject.markNeedsLayout();
} else {
// We have to reinvoke our builders because they might return new data.
@@ -197,20 +201,20 @@ class _MixedViewportElement extends RenderObjectElement<MixedViewport> {
assert(renderObject != null);
final int startIndex = _firstVisibleChildIndex;
int lastIndex = startIndex + _childrenByKey.length - 1;
Element nextSibling = null;
for (int index = lastIndex; index >= startIndex; index -= 1) {
Element previousChild = null;
for (int index = startIndex; index <= lastIndex; index += 1) {
final Widget newWidget = _buildWidgetAt(index);
final _ChildKey key = new _ChildKey.fromWidget(newWidget);
final Element oldElement = _childrenByKey[key];
assert(oldElement != null);
final Element newElement = updateChild(oldElement, newWidget, nextSibling);
final Element newElement = updateChild(oldElement, newWidget, previousChild);
assert(newElement != null);
_childrenByKey[key] = newElement;
// Verify that it hasn't changed size.
// If this assertion fires, it means you didn't call "invalidate"
// before changing the size of one of your items.
assert(_debugIsSameSize(newElement, index, _lastLayoutConstraints));
nextSibling = newElement;
previousChild = newElement;
}
}
}
@@ -283,8 +287,7 @@ class _MixedViewportElement extends RenderObjectElement<MixedViewport> {
Element _getElement(int index, BoxConstraints innerConstraints) {
assert(index <= _childOffsets.length - 1);
final Widget newWidget = _buildWidgetAt(index);
final Element newElement = _inflateOrUpdateWidget(newWidget);
return newElement;
return _inflateOrUpdateWidget(newWidget);
}
// Build the widget at index.
@@ -293,8 +296,7 @@ class _MixedViewportElement extends RenderObjectElement<MixedViewport> {
final Widget newWidget = _maybeBuildWidgetAt(index);
if (newWidget == null)
return null;
final Element newElement = _inflateOrUpdateWidget(newWidget);
return newElement;
return _inflateOrUpdateWidget(newWidget);
}
// Build the widget at index, handling the case where there is no such widget.
@@ -349,39 +351,39 @@ class _MixedViewportElement extends RenderObjectElement<MixedViewport> {
return result;
}
double _getMaxExtent(BoxConstraints constraints) {
switch (widget.direction) {
case Axis.vertical:
assert(constraints.maxHeight < double.INFINITY &&
'There is no point putting a lazily-built vertical MixedViewport inside a box with infinite internal ' +
'height (e.g. inside something else that scrolls vertically), because it would then just eagerly build ' +
'all the children. You probably want to put the MixedViewport inside a Container with a fixed height.' is String);
return constraints.maxHeight;
case Axis.horizontal:
assert(constraints.maxWidth < double.INFINITY &&
'There is no point putting a lazily-built horizontal MixedViewport inside a box with infinite internal ' +
'width (e.g. inside something else that scrolls horizontally), because it would then just eagerly build ' +
'all the children. You probably want to put the MixedViewport inside a Container with a fixed width.' is String);
return constraints.maxWidth;
}
}
/// This is the core lazy-build algorithm. It builds widgets incrementally
/// from index 0 until it has built enough widgets to cover itself, and
/// discards any widgets that are not displayed.
void _doLayout(BoxConstraints constraints) {
Map<_ChildKey, Element> newChildren = new Map<_ChildKey, Element>();
Map<int, Element> builtChildren = new Map<int, Element>();
final Map<_ChildKey, Element> newChildren = new Map<_ChildKey, Element>();
final Map<int, Element> builtChildren = new Map<int, Element>();
// Establish the start and end offsets based on our current constraints.
double extent;
switch (widget.direction) {
case Axis.vertical:
extent = constraints.maxHeight;
assert(extent < double.INFINITY &&
'There is no point putting a lazily-built vertical MixedViewport inside a box with infinite internal ' +
'height (e.g. inside something else that scrolls vertically), because it would then just eagerly build ' +
'all the children. You probably want to put the MixedViewport inside a Container with a fixed height.' is String);
break;
case Axis.horizontal:
extent = constraints.maxWidth;
assert(extent < double.INFINITY &&
'There is no point putting a lazily-built horizontal MixedViewport inside a box with infinite internal ' +
'width (e.g. inside something else that scrolls horizontally), because it would then just eagerly build ' +
'all the children. You probably want to put the MixedViewport inside a Container with a fixed width.' is String);
break;
}
final double endOffset = widget.startOffset + extent;
final double endOffset = widget.startOffset + _getMaxExtent(constraints);
// Create the constraints that we will use to measure the children.
final BoxConstraints innerConstraints = _getInnerConstraints(constraints);
// Before doing the actual layout, fix the offsets for the widgets whose
// size has apparently changed.
if (!isValid) {
if (!_isValid) {
assert(_childOffsets.length > 0);
assert(_childOffsets.length == _childExtents.length + 1);
List<int> invalidIndices = _invalidIndices.toList();
@@ -512,13 +514,12 @@ class _MixedViewportElement extends RenderObjectElement<MixedViewport> {
assert(!haveChildren || startIndex < _childExtents.length);
// Build the other widgets that are visible.
int index = startIndex;
int index;
if (haveChildren) {
// Update the renderObject configuration
renderObject.direction = renderObject.direction;
renderObject.startOffset = _childOffsets[index] - widget.startOffset;
renderObject.startOffset = _childOffsets[startIndex] - widget.startOffset;
// Build all the widgets we still need.
while (_childOffsets[index] < endOffset) {
for (index = startIndex; _childOffsets[index] < endOffset; index += 1) {
if (!builtChildren.containsKey(index)) {
Element element = _maybeGetElement(index, innerConstraints);
if (element == null) {
@@ -543,7 +544,6 @@ class _MixedViewportElement extends RenderObjectElement<MixedViewport> {
builtChildren[index] = element;
}
assert(builtChildren[index] != null);
index += 1;
}
}
@@ -554,6 +554,7 @@ class _MixedViewportElement extends RenderObjectElement<MixedViewport> {
}
if (haveChildren) {
assert(index != null);
// Place all our children in our RenderObject.
// All the children we are placing are in builtChildren and newChildren.
Element previousChild = null;

46
packages/flutter/test/widget/mixed_viewport_test.dart
View File

@@ -150,4 +150,50 @@ void main() {
callbackTracker.clear();
});
});
test('MixedViewport reinvoke builders', () {
testWidgets((WidgetTester tester) {
List<int> callbackTracker = <int>[];
List<String> text = <String>[];
IndexedBuilder itemBuilder = (BuildContext context, int i) {
callbackTracker.add(i);
return new Container(
key: new ValueKey<int>(i),
width: 500.0, // this should be ignored
height: 220.0,
child: new Text("$i")
);
};
ElementVisitor collectText = (Element element) {
final Widget widget = element.widget;
if (widget is Text)
text.add(widget.data);
};
Widget builder() {
return new MixedViewport(
builder: itemBuilder,
startOffset: 0.0
);
}
tester.pumpWidget(builder());
expect(callbackTracker, equals([0, 1, 2]));
callbackTracker.clear();
tester.walkElements(collectText);
expect(text, equals(['0', '1', '2']));
text.clear();
tester.pumpWidget(builder());
expect(callbackTracker, equals([0, 1, 2]));
callbackTracker.clear();
tester.walkElements(collectText);
expect(text, equals(['0', '1', '2']));
text.clear();
});
});
}