fix(toolbox): respect series.stack when switching magicType stack. close #15571

[b84330808]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

Make the magicType stack button recognize series that are already stacked by series.stack, and restore those stack groups when switching back from tiled.

Fixed issues

• MagicType 'stack' does not recognize bars being stacked upon chart initialization, fails to change to tiled on first click. #15571: MagicType 'stack' does not recognize bars being stacked upon chart initialization, fails to change to tiled on first click.

Details

Before: What was the problem?

The stack button only treated a series as stacked when its stack was the inner keyword set by the button itself (__ec_magicType_stack__). For series stacked by users (e.g. stack: 'cars'):

• The first click "stacked" them again, so nothing visibly changed, and it only took effect on the second click.
• Separate user stack groups (e.g. groupA and groupB) were merged into one single stack, and the original groups were never restored.

After: How does it behave after the fixing?

• Whether the chart is currently stacked is decided once per click over all target line/bar series: it is stacked if any series uses the magicType inner stack, or if any series.stack value is shared by more than one series. So user-stacked charts switch to tiled on the first click.
• When switching to tiled, the user-defined stack values are remembered per series id on the global model (like the dataZoom history) and restored when switching back. Series without a user-defined stack still use the inner magicType stack as before.
• Existing behaviors are kept: charts without stacks, a single series, and a stack name used by only one series (as in test/toolbox-stack.html) toggle the same way as before.

Added unit tests in test/ut/spec/component/toolbox/magicType.test.ts. They click the actual toolbox icon, and 3 of them fail without this change. The full unit test suite, tsc --noEmit and eslint pass.

I used Claude Code to write this change.

Document Info

One of the following should be checked.

• This PR doesn't relate to document changes
• The document should be updated later
• The document changes have been made in apache/echarts-doc#xxx

Misc

Security Checking

• This PR uses security-sensitive Web APIs.

ZRender Changes

• This PR depends on ZRender changes (ecomfe/zrender#xxx).

Related test cases or examples to use the new APIs

test/ut/spec/component/toolbox/magicType.test.ts

Merging options

• Please squash the commits into a single one when merging.

Other information

Related reports: #16473, #20371, #20031, #13103.

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