Fix 11781: save svg image with toolbox

[Ovilia]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

To support saving SVG images with toolbox. Also works for connected charts.

Fixed issues

• Bug: download svg image with toolbox #11781: Bug: download svg image with toolbox

Details

Before: What was the problem?

1. Default suffix of the downloaded file with SVG charts was .png if saveAsImage.type is not set manually, which should be .svg because the downloaded file is an SVG file.
2. The downloaded SVG has an error in it and cannot be opened even after changing the file suffix to be .svg
3. It didn't work for connected charts.

After: How is it fixed in this PR?

1. The default suffix is .svg if the chart renderer is 'svg'.
2. No error after the fix.
3. It works for connected charts now and the background is set to be connectedBackgroundColor, which is the same as Canvas behavior.

Usage

Are there any API changes?

• The API has been changed.

Related test cases or examples to use the new APIs

Test case: toolbox-saveImage-background-svg.html

The saved SVG file should look the same as the charts.

Others

Merging options

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

Other information

[echarts-bot]

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[echarts-bot]

Congratulations! Your PR has been merged. Thanks for your contribution! 👍