[GongHeng2017]

Root Cause Analysis

When the magnifier is moved to a non-content area (outside document pages), BrowserMagniFier::setMagniFierImage() receives a null QImage and enters the else branch, where it fills the magnifier center with Qt::white. Since Qt::white is a fixed Qt color constant (QColor(255,255,255)) that does not respond to theme changes, the magnifier center displays pure white even in dark mode, creating a jarring contrast with the dark background (~#2B2B2B).

Key evidence: reader/browser/BrowserMagniFier.cpp:207 hardcodes Qt::white; the same module's SheetBrowser.cpp:72 already uses the theme-aware DGuiApplicationHelper::instance()->applicationPalette().itemBackground().color().

Fix

Replace Qt::white at line 207 with DGuiApplicationHelper::instance()->applicationPalette().itemBackground().color(), and add #include <DGuiApplicationHelper>. This is consistent with the existing pattern in SheetBrowser.cpp:72.

Change Safety Assessment

Code Safety

• Risk Level: Low
• Target line was introduced in the initial magnifier implementation (commit 9417b7de8, 2020-07-14), not a previous bug fix product; this change does not revert any historical fix
• setMagniFierImage() is a private rendering method with only 3 internal callers; no signature change, no caller impact

Business Impact Scope

• Affected module: Document viewer magnifier tool
• User scenario: In dark mode, moving the magnifier to non-content areas now shows the theme background color instead of pure white
• No impact on normal magnifier behavior (showing page content) — only the null-image fallback path changes

Verification Suggestion

Test the magnifier tool in both light and dark modes: move it onto and off document pages, verify the center area follows the theme in dark mode and remains consistent in light mode.

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根因分析

深色模式下放大镜移至非内容区域时，BrowserMagniFier::setMagniFierImage() 收到空 QImage 进入 else 分支，使用 Qt::white 填充放大镜中心。Qt::white 是 Qt 固定常量（QColor(255,255,255)），不随主题变化，导致深色模式下放大镜中心显示纯白，与深色背景（约 #2B2B2B）形成刺眼反差。

关键证据：reader/browser/BrowserMagniFier.cpp:207 硬编码 Qt::white；同模块 SheetBrowser.cpp:72 已使用主题感知的 DGuiApplicationHelper::instance()->applicationPalette().itemBackground().color()。

修复方案

将第 207 行的 Qt::white 替换为 DGuiApplicationHelper::instance()->applicationPalette().itemBackground().color()，并添加 #include <DGuiApplicationHelper>，与 SheetBrowser.cpp:72 保持一致。

改动安全评估

代码安全评估

• 风险等级: 低风险
• 目标行引入于放大镜初始实现（commit 9417b7de8, 2020-07-14），非历史 bug 修复产物；本次改动不撤销任何历史修复
• setMagniFierImage() 是私有渲染方法，仅 3 个内部调用方；签名不变，调用方无影响

业务影响范围

• 受影响模块：文档查看器放大镜工具
• 用户场景：深色模式下放大镜移至非内容区域时，中心区域跟随主题显示背景色，不再为纯白
• 正常放大镜行为（显示页面内容）不受影响，仅空图像兜底路径变化

验证建议

在浅色和深色模式下测试放大镜工具：将放大镜移入和移出文档页面，验证深色模式下中心区域跟随主题，浅色模式保持一致。

Summary by Sourcery

Make the document magnifier’s empty-area background follow the application theme.

Bug Fixes:

• Use the active theme background color for the magnifier fallback area when no document image is available, preventing a jarring white center in dark mode.

Chores:

• Update the BrowserMagniFier copyright year range.

[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: GongHeng2017

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• debian/deepin/OWNERS

Approvers can indicate their approval by writing /approve in a comment
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[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Updates the magnifier’s non-content fallback rendering to obtain its fill color from the application palette, preventing a white center from clashing with dark mode while preserving existing content rendering behavior.

Sequence diagram for theme-aware magnifier fallback rendering

sequenceDiagram
    participant BrowserMagniFier
    participant DGuiApplicationHelper
    participant QPainter

    BrowserMagniFier->>BrowserMagniFier: setMagniFierImage(image)
    alt image contains page content
        BrowserMagniFier->>QPainter: drawImage()
    else image is null
        BrowserMagniFier->>DGuiApplicationHelper: instance()
        DGuiApplicationHelper-->>BrowserMagniFier: applicationPalette()
        BrowserMagniFier->>QPainter: fillRect(itemBackground().color())
    end

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File-Level Changes

Change	Details	Files
Make the magnifier’s null-image fallback use the active application theme background instead of a hardcoded white color.	Add the DGuiApplicationHelper dependency. Use the palette item background color when filling the magnifier outside document content. Leave normal page-image rendering and the method interface unchanged.	reader/browser/BrowserMagniFier.cpp

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