NumberPicker | kotlin 数字选择器

You can use the onGloballyPositioned modifier to retrieve the position of a composable and then use the method scrollState.animateScrollTo to scroll to that position.

Something like:

You can use a combination of SizedBox and FittedBox to achieve any kind of scale manipulation of Widgets.

For your case, you can use it like this,

If you done all this processes you should have latest dart SDK installed on your machine as well as Android Studio.

The actual problem accrues due to dart version specified in your pubspec.yaml file.

In pubspec.yaml file there is a code like this:

You are never initialising countersDatabase in CounterHolder, hence the NullPointerException.

Change test.text = "\(possibleNums[numberPicker.selectedRow(inComponent: 0)])" to this: test.text = "\(possibleNums[row])"

You only have one component, so you don't need to check for it, just return the row number as the array's index.

You need to install ffi dependency manually. Here is the same issue on GitHub: https://github.com/flutter/flutter/issues/70796. Also, if you have troubles with build or run you app on M1, visit to Wiki page on GitHub with usage guide and this issue for tracking current support phase for new macs.

Take a look at ConstraintSet. There are some tutorials online on how to use ConstraintSets to create and modify constraints programmatically.

You might also make use of GONE widgets. The second EditText could have a visibility of "gone" so that the bottom button would float up to be under the first EditText and float down when the second EditText is visible.

This is because you did not set onValueChangeListener to mHourSpinner. Try this instead:

Ok, here's your problem. You want a wheel with 00 and 30 on it, and you want to be able to infinitely scroll it, so it ticks over from 30 to 00 and increments the hour wheel each time, right? Which is basically how the TimePicker works by default.

The issue is this, from NumberPicker:

Note: If the number of items, i.e. the range ( getMaxValue() - getMinValue()) is less than the number of items shown on the selector wheel, the selector wheel will not wrap.

the max - min thing is an extremely awkward way of expressing this (the number of items is actually that + 1) - but basically the spinner shows three items on-screen at a time, and you need to have more than three items (so at least one is off-screen) for wrapping to work. That's why is works for your other intervals (15 mins gives you four items, so that wraps)

Unfortunately I don't think there's a lot you can do about it - the lack of wrapping is hardcoded behaviour in NumberPicker. You could fake it by having four items, 00, 30, 00, 30 but internally that's still values 0 to 3, one rotation of the wheel, not two. And the TimePicker uses those values, comparing to minValue and maxValue to check when the wheel has wrapped and the hour needs to automatically change.

The listener that handles this (in TimePickerSpinnerDelegate) can't be read, so you can't wrap it in a listener that pretends it's going 0 1 0 1 instead. The listener also refers to a bunch of internal private variables and methods, so you can't just copy it into your own code and make the tweaks. You'd have to reimplement the whole widget and its related classes by the looks of things

If it works for you, you could just throw two NumberPickers together and remake it yourself. You'll lose things like the AM/PM functionality, probably accessibility, it depends if you care or not. This basically works: