fix: Terminal theme color not updating with application theme changes

[JWWTSL]

log: TermWidget::onThemeTypeChanged responds to the DTK DGuiApplicationHelper::themeTypeChanged signal. However, it only checks whether extendColorScheme is empty. Since two out of the three terminal theme states have an empty extendColorScheme, the theme fails to update correctly in those cases.

pms: bug-365877

Summary by Sourcery

Ensure terminal color scheme updates correctly when following the system theme and remains stable when a fixed theme is selected.

Bug Fixes:

• Fix terminal theme not updating when configured to follow the system light/dark theme due to ambiguous extendColorScheme state.

Enhancements:

• Preserve user-selected fixed light or dark terminal themes by ignoring system theme change signals in that mode.

Chores:

• Update source file copyright years to include 2026.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Updates TermWidget theme-change handling so that terminal colors only follow system light/dark changes when the terminal is configured to follow the system theme, avoiding unintended theme switches when a fixed light/dark theme is selected.

Sequence diagram for updated theme change handling in TermWidget

sequenceDiagram
    participant DGuiApplicationHelper
    participant TermWidget
    participant Settings

    DGuiApplicationHelper->>TermWidget: onThemeTypeChanged(builtInTheme)
    TermWidget->>Settings: extendColorScheme()
    Settings-->>TermWidget: expandThemeStr

    alt [expandThemeStr is not empty]
        Note right of TermWidget: Use extended theme (unchanged)
    else [expandThemeStr is empty]
        TermWidget->>DGuiApplicationHelper: paletteType()
        DGuiApplicationHelper-->>TermWidget: paletteType
        alt [paletteType is not UnknownType]
            Note right of TermWidget: Fixed light/dark theme, ignore signal
            TermWidget-->>DGuiApplicationHelper: return
        else [paletteType is UnknownType]
            Note right of TermWidget: Follow system light/dark
            TermWidget->>TermWidget: setColorScheme(theme)
            TermWidget->>Settings: setColorScheme(theme)
        end
    end

Loading

File-Level Changes

Change	Details	Files
Refine terminal theme update logic to distinguish between fixed themes and follow-system mode when handling system theme changes.	Read extendColorScheme from Settings as before to detect whether an extended theme is configured Document in comments that both fixed light/dark and follow-system states have empty extendColorScheme and must be distinguished via paletteType Add a guard that returns early from onThemeTypeChanged when paletteType is not UnknownType, meaning a fixed light or dark theme is selected Keep existing behavior of mapping DGuiApplicationHelper::LightType to "Light" and other values to "Dark", and persisting this in Settings when in follow-system mode	src/views/termwidget.cpp
Update copyright years in TermWidget source file.	Extend copyright range from 2019 ~ 2020 to 2019 ~ 2026 in the file header	src/views/termwidget.cpp

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[sourcery-ai]

Hey - I've left some high level feedback:

• The logic branching on paletteType() != DGuiApplicationHelper::UnknownType is a bit opaque; consider extracting this into a named helper (e.g. isFollowSystemThemeEnabled()) or centralizing the state check so the meaning of UnknownType and the three theme modes is clearer and less error-prone if the enum or modes change later.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- The logic branching on `paletteType() != DGuiApplicationHelper::UnknownType` is a bit opaque; consider extracting this into a named helper (e.g. `isFollowSystemThemeEnabled()`) or centralizing the state check so the meaning of `UnknownType` and the three theme modes is clearer and less error-prone if the enum or modes change later.

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[JWWTSL]

/forcemerge

[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: JWWTSL, lzwind

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