Let iOS have a minimum scroll movement threshold to break before motion starts #13166
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Hixie
reviewed
Nov 29, 2017
| assert(details != null), | ||
| assert( | ||
| motionStartDistanceThreshold == null || motionStartDistanceThreshold > 0.0, | ||
| 'Must be a positive number or null' |
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This should say what must be positive or null. The error message will have no context.
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Seems like asserts with optional messages actually shows both the assert test code and the message.
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Yes, but experience shows our users don't understand the assertion test code. They only read the text (if we're lucky). (The framework actually flips the message around so the message comes first and the assert code is second, now.)
Hixie
reviewed
Nov 29, 2017
| @required DragStartDetails details, | ||
| this.onDragCanceled, | ||
| this.carriedVelocity, | ||
| this.motionStartDistanceThreshold |
Hixie
reviewed
Nov 29, 2017
| /// Returns false either way if there's no offset. | ||
| bool _breakMotionStartThreshold(double offset, Duration timestamp) { | ||
| if (timestamp == null) { | ||
| // If we can't track time, we can't apply thresholds. Should never happen. |
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If it should never happen, assert instead?
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Clarified comment. Can be null with accessibility gestures
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DaveShuckerow
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May 14, 2018
…on starts (flutter#13166) * Add a minimum distance that needs breaking on iOS each time scrolls stopped. * Testing and tests * tweak docs * review
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Fixes #12181
Mimics native behaviour. Android unaffected.