Dark color improvement

[JiuqingSong]

When call color callback to calculate dark color, pass in the text color for background color so the callback function can calculate a better background color according to the text color.

And in order to allow different background dark color for different text color, also add text color to background color key.
Example:
old color key: --darkColor__f5d427 (here #f5d427 is the light mode background color)
new color key: --darkColor__f5d427__ff0000 (here #ff0000 is the light mode text color)

[Copilot]

Pull request overview

This PR improves dark-mode background color generation by letting the dark color callback consider the associated text color, and by incorporating the text color into the generated dark color CSS variable key so different foreground/background pairings can produce different dark backgrounds.

Changes:

• Extend dark color transformation APIs to accept an optional comparingColor (intended to be text color when generating dark backgrounds).
• Update dark color key generation to include comparingColor (e.g. --darkColor_<bg>_<text>), and propagate inherited text color during DOM color transformation.
• Update and add tests to reflect the new key format and call signatures.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
packages/roosterjs-editor-adapter/lib/editor/EditorAdapter.ts	Passes editor default text color into transformColor during dark color transformation.
packages/roosterjs-content-model-types/lib/context/DarkColorHandler.ts	Extends ColorTransformFunction signature to include optional comparingColor.
packages/roosterjs-content-model-dom/lib/formatHandlers/utils/color.ts	Threads comparingColor through setColor/adaptColor and updates default key generation to append it.
packages/roosterjs-content-model-dom/lib/formatHandlers/common/backgroundColorFormatHandler.ts	Passes text color as comparingColor when applying background color in dark mode.
packages/roosterjs-content-model-dom/lib/domUtils/style/transformColor.ts	Propagates parent/inherited text color to improve background dark color generation and keying.
packages/roosterjs-content-model-core/lib/editor/Editor.ts	Passes editor default text color into transformColor when toggling dark mode.
packages/roosterjs-content-model-dom/test/formatHandlers/utils/colorTest.ts	Updates expectations for new key format and getDarkColor argument list.
packages/roosterjs-content-model-dom/test/formatHandlers/common/backgroundColorFormatHandlerTest.ts	Adds coverage for combined text+background in dark mode affecting background key.
packages/roosterjs-content-model-dom/test/domUtils/style/transformColorTest.ts	Updates expected background keys and adds inherited text color scenario coverage.
packages/roosterjs-content-model-core/test/editor/EditorTest.ts	Updates transformColor call expectations for the new optional parameter.

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[Copilot]

backgroundColorFormatHandler is now typed as FormatHandler<BackgroundColorFormat & TextColorFormat>, but the default format handler registry expects FormatHandler<BackgroundColorFormat> (see FormatHandlerTypeMap.backgroundColor). This can cause a TypeScript assignability error (or force callers/tests to widen types) even though textColor is only used as an optional hint.

Suggested fix: keep the handler typed as FormatHandler<BackgroundColorFormat> and read comparing text color via a safe cast (e.g., const comparingColor = (format as Partial<TextColorFormat>).textColor ?? context.implicitFormat.textColor) when calling setColor.

[Copilot]

The new comparingColor param doc says it helps ensure the generated "dark border color" has enough contrast, but this type is used for generating dark colors in general and the param is specifically described as for background-vs-text contrast. Please update the wording to refer to "dark background color" (or generally "generated dark color"), not border color.

Suggested change

	* @param comparingColor @optional When generating dark color for background color, we can provide text color as comparingColor to make sure the generated dark border color has enough contrast with text color in dark mode
	* @param comparingColor @optional When generating dark color for background color, we can provide text color as comparingColor to make sure the generated dark background color has enough contrast with text color in dark mode

[Copilot]

JSDoc for setColor's new comparingColor param mentions "generated dark border color", but this param is passed when generating dark background colors (to keep contrast with text). Please correct the wording so it matches the actual behavior.

Suggested change

	* @param comparingColor @optional When generating dark color for background color, we can provide text color as comparingColor to make sure the generated dark border color has enough contrast with text color in dark mode
	* @param comparingColor @optional When generating dark color for a background, we can provide the text color as comparingColor to make sure the generated dark background color has enough contrast with the text color in dark mode

[Copilot]

transformColor now has a new defaultTextColor parameter (used to propagate inherited text color for background contrast), but the exported function's documentation block above doesn't describe it. Please update the JSDoc to include this parameter and its effect on background color transformation.