Gang929 fix stacked area series negative

[beto-rodriguez]

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[github-actions]

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[Copilot]

Pull request overview

Adjusts the stacking accumulation logic in Stacker.StackPoint to address incorrect behavior for negative values in stacked area-like series.

Changes:

• Updates how StackedValue.End/NegativeEnd are incremented during stacking.
• Updates how per-index positive/negative totals are accumulated.

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[Copilot]

In the value >= 0 branch, the code now also adds the positive value to currentStack.NegativeEnd and _totals[index].Negative. That mixes the positive and negative stacks/totals; it will shift NegativeEnd upward and make NegativeTotal positive, which breaks later negative stacking (next series uses previousActiveStack.NegativeEnd) and can produce incorrect StackedValue.Share / bounds.

Suggested change

	currentStack.End += value;
	currentStack.NegativeEnd += value;
	var positiveTotal = _totals[index].Positive + value;
	_totals[index].Positive = positiveTotal;
	var negativeTotal = _totals[index].Negative + value;
	_totals[index].Negative = negativeTotal;
	return positiveTotal;
	}
	else
	{
	currentStack.End += value;
	currentStack.NegativeEnd += value;
	var negativeTotal = _totals[index].Negative + value;
	_totals[index].Negative = negativeTotal;
	var positiveTotal = _totals[index].Positive + value;
	_totals[index].Positive = positiveTotal;
	// positive values contribute only to the positive stack and positive totals
	currentStack.End += value;
	var positiveTotal = _totals[index].Positive + value;
	_totals[index].Positive = positiveTotal;
	return positiveTotal;
	}
	else
	{
	// negative values contribute only to the negative stack and negative totals
	currentStack.NegativeEnd += value;
	var negativeTotal = _totals[index].Negative + value;
	_totals[index].Negative = negativeTotal;

[Copilot]

In the value < 0 branch, the code now also adds the negative value to currentStack.End and _totals[index].Positive. That contaminates the positive stack baseline (previousActiveStack.End is used as the next series' positiveStart) and can make Total incorrect/negative, affecting stacked rendering and axis bounds.

Suggested change

	currentStack.End += value;
	currentStack.NegativeEnd += value;
	var positiveTotal = _totals[index].Positive + value;
	_totals[index].Positive = positiveTotal;
	var negativeTotal = _totals[index].Negative + value;
	_totals[index].Negative = negativeTotal;
	return positiveTotal;
	}
	else
	{
	currentStack.End += value;
	currentStack.NegativeEnd += value;
	var negativeTotal = _totals[index].Negative + value;
	_totals[index].Negative = negativeTotal;
	var positiveTotal = _totals[index].Positive + value;
	_totals[index].Positive = positiveTotal;
	// positive values contribute only to the positive stack and total
	currentStack.End += value;
	var positiveTotal = _totals[index].Positive + value;
	_totals[index].Positive = positiveTotal;
	return positiveTotal;
	}
	else
	{
	// negative values contribute only to the negative stack and total
	currentStack.NegativeEnd += value;
	var negativeTotal = _totals[index].Negative + value;
	_totals[index].Negative = negativeTotal;

[Copilot]

@beto-rodriguez I've opened a new pull request, #2087, to work on those changes. Once the pull request is ready, I'll request review from you.

[github-actions]

Thanks for your contribution!

The build and test process is starting. This may take a while.
You can find more details below as the process continues or at the actions tab.

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All packages have been packed successfully! 📦✅
You can download the NuGet packages for this build here.

The packages will be available for 30 days, you can either use them directly, or wait for this PR to be merged to have them published to NuGet.org.

---

Tests will start now, you can monitor their progress below or at the actions tab.

Test Results Summary (Passed) ✅ 🥳

0 skipped.
0 failed.
1233 passed! ✅