Create a WidgetTester extension to drag scroll bars (Resolves #22) #23
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lib/src/scrollbar.dart
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| /// Simulates the user interacting with a Scrollbar. | ||
| extension ScrollbarInteractions on WidgetTester { | ||
| /// Press a scrollbar thumb at [thumbLocation] and drag it vertically by [delta] pixels. | ||
| Future<void> dragScrollbar(Offset thumbLocation, double delta) async { |
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How does the user know where there scrollbar thumb is located?
Also, we should use this in a test in this package to demonstrate that it works, and show how we expect others to use it.
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Currently, there is no way to find the thumb. I filed flutter/flutter#161403.
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I think if the caller has to provide the thumb location then this doesn't have much value. Can you think of any workaround so that a caller can essentially say "drag the scrollbar 100px down"?
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The only way it would work at the moment is if the thumb sits at the top-right of the widget. If it is at any other place, we cannot know its position.
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Can can't make an educated guess? What if we check the associated scroll offset, total content height, and the height of the scrollbar? Wouldn't that tell us where the thumb should be?
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I think that, if we want to support, all scrollbar's configurations (vertical x horizontal, LTR x RTL, thumb margin, etc), we probably need most of this code...
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I'd appreciate specificity instead of generalities. In terms of a vertical scrollbar, where does my suggestion fail?
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It would fail for situations when there is margin/padding on the scrollbar (although it would be simple to add it to this code), and if it's placed on the left side instead of the right side.
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What does it mean for there to be margin/padding on the scrollbar?
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With margin, the thumb won't use the whole track, there will be an empty space at the edges of the scrollbar.
The padding can be applied to top/bottom/left/right, which means that the thumb might not be placed exactly at the right edge of the scrollable widget.
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lib/src/scrollbar.dart
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| /// | ||
| /// By default, this method expects a single [Scrollbar] in the widget tree and | ||
| /// finds it `byType`. To specify one [Scrollbar] among many, pass a [finder]. | ||
| Future<void> dragScrollbar(double delta, [Finder? finder]) async { |
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We should make this action even more clear by adding the direction to the method name, e.g., dragScrollbarDown(300) and dragScrollbarUp(300)
Create a WidgetTester extension to drag scroll bars. Resolves #22
Dragging a scrollbar requires hovering over the scroll bar, waiting for it to appear, and then dragging and releasing it.
This PR adds a
dragScrollbarmethod yo make it easier to interacting with a scrollbar.We can't use a finder to locate the scrollbar thumb because the scrollbar widget uses a single painter to paint both the scrollbar track and the thumb.
We have a
kTapMinTimeconstant in super_editor that we use in the tests. I needed to use the value directly here.