Fix Slider snap-to-tick floating-point precision (#8819)#11719
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Fix Slider snap-to-tick floating-point precision (#8819)#11719JyslaFancy wants to merge 1 commit into
JyslaFancy wants to merge 1 commit into
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When IsSnapToTickEnabled=True and TickFrequency=0.1, values like 1.9 could become 1.9000000000000001 after snapping instead of 2.0 due to floating-point arithmetic in the TickFrequency multiplication. Fix: After computing the snapped value, round it to the number of decimal places implied by TickFrequency using MidpointRounding.AwayFromZero. Applied in both SnapToTick() and MoveToNextTick() methods. Fixes dotnet#8819
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Description
Fixes #8819: WPF Slider snap-to-tick floating-point precision bug.
When and , values like could become after snapping instead of . This happens because the multiplication in double-precision floating-point arithmetic introduces small rounding errors.
Root Cause
In , the snap-to-tick calculation at line ~1184:
The multiplication reintroduces floating-point errors. For example, in double arithmetic produces instead of .
Fix
After computing the snapped value, round it to the number of decimal places implied by using . This eliminates the floating-point artifacts without affecting valid values.
Added a helper method that determines the appropriate rounding precision from the value. Applied the fix in both and methods.
Testing
Microsoft Reviewers: Open in CodeFlow