Add peek feature to PageView #8539
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| double get peek => _peek; | ||
| double _peek; | ||
| set peek (double newValue) { | ||
| assert(newValue != null); |
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maybe assert > 0, <= 1.0 ?
(would it work with > 1.0?)
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Oh, I see, peek values are absolute pixels. This seems surprising, I would have expected it to be a fraction of the viewportMainAxisExtent.
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I guess it works either way. I don't know what our customers prefer.
| @@ -264,4 +264,42 @@ void main() { | |||
| expect(find.text('Alaska'), findsOneWidget); | |||
| }); | |||
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| testWidgets('PageView peek', (WidgetTester tester) async { | |||
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we should test that this handles the main axis extent changing (without rebuilding) when the peek is non-zero.
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I didn't verify the math, but LGTM. |
| final int initialPage; | ||
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| /// The number of pixels of the next and previous page that should be visible | ||
| /// before and after the current page. | ||
| final double peek; |
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Another way to define this would have been been pageWidth as a percentage of the viewport's width. The default and the maximum would be 1.0.
On a wide screen, like a tablet, you might want to define the pageWidth with a small enough value so that the entire next/prev pages are visible.
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Maybe that's better. I'll give that a try.
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Yeah, that seems cleaner.
| @override | ||
| PageScrollPhysics applyTo(ScrollPhysics parent) => new PageScrollPhysics(parent: parent); | ||
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| double _getPage(ScrollPosition position) { |
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Does this work if peek > viewportDimension / 4, i.e. if 3 or more pages are visible after the pageview has settled?
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I'll add a test for that, but it should work in theory.
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That works. I also tested viewportFractions greater than one.
This feature lets you see a portion of the next and previous page in a PageView. Fixes flutter#8408
This feature lets you see a portion of the next and previous page in a
PageView.
Fixes #8408