[Core] Fix Slider Maximum , Minimum binding issue

[myroot]

Description of Change

Remove validateValue handler on Maximum/Minimum properties
Use propertyChanged for Maximum/Minimum integrity

Bugs Fixed

• fixes Slider crashes when Minimum value greater than zero and set before Max value in XAML #1943
• fixes [Core] Slider unable to update Maximum , Minimum by binding #2761

API Changes

None

Behavioral Changes

Allow set Minimum value that greater than Maximum value, after Minimum was updated, Maximum value is changed to Max(Minimum, Maximum)

Allow set Maximum value that smaller than Minimum, after Maximum was updated, Minimum value is changed to Min(Minimum, Maximum)

PR Checklist

• Has tests (if omitted, state reason in description)
• Rebased on top of the target branch at time of PR
• Changes adhere to coding standard
• Consolidate commits as makes sense

[StephaneDelcroix]

The effects of this might be even more wrong than the current behavior.

<Slider
  Value="{Binding Value}"
  Min="{Binding Min}"
  Max="{Binding Max}" />

with a context of new {Value=-50, Min=-100, Max=-1}

the min and max will be correct, but the value will be coerced at -1

[myroot]

Binding the Value is difficult issue to solve. because It is twoway binding.
But I don't think fixed behavior is more wrong than the current behavior

-	Can binding to Maximum/Minimum	Can binding to Value	Cause crash?
current behavior	X	X	O
fixed behavior	O	X	X

[charlesroddie]

Looks like nothing will quite work here. With the way the current properties work, you are bound to have invalid or incorrect states.

You could add a property that is guaranteed to work, SliderValues, which has a type that contains all three floats Min, Max, and Current.

And then leave the existing three properties in a partially fixed state, where they work in more situations than they did before, but not all.

[kingces95]

Huh. Seems intractable; XAML doesn't have syntax to declare dependencies between properties to control how they are assigned. So if a dependency exists (e.g. value -> min, value -> max) then there is no way to express it in XAML and honor the dependencies. Yet Windows Phone has Min and Max properties. So maybe I'm wrong and the dependency can be expressed? Wonder why didn't they just have a single property Percentage of type double that varies between 0 and 1? Anyway, @StephaneDelcroix is the expert so if it is intractable, he'll know the least worst solution.

[charlesroddie]

Here is an idea:

Setting Min, Value, Max would set internal mutable variables reqMin, reqVal, reqMax. Getting Value, Min, Max gets the actual values, which are a function of the these req values. If reqMin ≤ reqVal ≤ reqMax then the actual values are (reqMin,reqVal,reqMax). If not, then the actual values take some other valid numbers, maybe (0,0,1) or (a,b,c) where
a = min(reqMin,reqVal,reqMax), c = max(...) and b = min(max(a,reqVal),c).

This would not prevent temporary glitches in Min, Value, Max (and so as a purist I would still say the correct fix is to have a single float*float*float property instead of three float properties) but it would prevent these glitches from having lasting effects (@StephaneDelcroix 's example) and also from crashing the UI (since the UI always gets valid inputs).