fix: guard null pointer in updateViewModeActions

[pengfeixx]

fix: guard null pointer in updateViewModeActions

1. Root cause: m_actLivePreview is initialized to nullptr and only
   assigned in initRightClickedMenu(), but updateViewModeActions() can
   be called via signal/slot before initialization completes
2. Fix: add null check before calling setEnabled on m_actLivePreview,
   consistent with the existing null-safe pattern on the preceding line
3. Impact: prevents null pointer dereference crash when switching view
   modes before right-click menu initialization

Influence:

1. Test switching view modes before opening right-click menu
2. Test markdown file open and view mode toggle
3. Verify no regression on normal view mode switching

fix: 修复updateViewModeActions空指针解引用问题

1. 根因：m_actLivePreview初始化为nullptr，仅在initRightClickedMenu()
   中赋值，但updateViewModeActions()可通过signal/slot在初始化前被调用
2. 方案：在调用m_actLivePreview->setEnabled前添加空指针检查，与同
   函数已有的空安全模式保持一致
3. 影响：防止右键菜单初始化前切换视图模式导致的空指针崩溃

Influence:

1. 测试右键菜单初始化前切换视图模式
2. 测试Markdown文件打开及视图模式切换
3. 验证正常视图模式切换无回归

PMS: BUG-186

Summary by Sourcery

Bug Fixes:

• Prevent a null-pointer crash when updating view-mode actions before the live-preview action is initialized.

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This pull-request has been approved by: pengfeixx

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[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Prevents a null-pointer dereference when view-mode signals invoke updateViewModeActions before the right-click menu initializes the live-preview action, while retaining normal Markdown and view-mode behavior.

Sequence diagram for guarded view mode action updates

sequenceDiagram
    participant ViewModeSignal
    participant TextEdit
    participant LivePreviewAction
    ViewModeSignal->>TextEdit: updateViewModeActions(mode, isMarkdown)
    TextEdit->>TextEdit: action->isChecked()
    TextEdit->>TextEdit: action->setChecked(true)
    alt m_actLivePreview initialized
        TextEdit->>LivePreviewAction: setEnabled(isMarkdown)
    else m_actLivePreview is null
        TextEdit-->>TextEdit: skip setEnabled
    end

Loading

File-Level Changes

Change	Details	Files
Guard live-preview action access during view-mode updates.	Check the action pointer before enabling or disabling it. Preserve existing Markdown-specific enablement behavior when the action is initialized.	src/editor/dtextedit.cpp

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[deepin-ci-robot]

deepin pr auto review

🤖 AI 代码审查报告

总体评分： 100 分 (通过阈值: 70分)

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📊 总体评价

项目	结果
审查结论	代码审查通过
评分详情	总体评分 100 分，大于 70 分通过阈值，代码质量符合要求。本次提交修复了 updateViewModeActions 函数中的空指针解引用问题，修改最小化且与同函数已有的空安全模式一致。

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🔍 详细分析

1. 语法逻辑 ✅

评价： 优秀 ✅ 通过

潜在问题：
✅ 未发现明显问题

建议： 语法正确，逻辑清晰。在调用 m_actLivePreview->setEnabled(isMarkdown) 前添加空指针检查，与同函数前一行 if (action && !action->isChecked()) 的空安全模式保持一致，修复了 m_actLivePreview 在 initRightClickedMenu() 赋值前通过 signal/slot 触发 updateViewModeActions() 导致的空指针解引用崩溃。

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2. 代码质量 ✅

评价： 优秀 ✅ 通过

潜在问题：
✅ 未发现明显问题

建议： 代码结构清晰，注释完整。修改仅涉及2行代码（1行删除、2行新增），变更最小化且聚焦。保留了原有注释「置灰规则（§4.4）：非 md 文件仅「实时预览」置灰，编辑/查看始终可用」，代码风格与上下文完全一致。

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3. 代码性能 ✅

评价： 优秀 ✅ 通过

潜在问题：
✅ 未发现明显问题

建议： 性能良好，资源使用合理。新增的空指针判断（if (m_actLivePreview)）为常数时间操作，开销可忽略不计，对性能无任何影响。

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4. 代码安全 🔒

评价： 优秀 ✅ 通过

🔐 发现 0 个安全漏洞

安全漏洞详情：
✅ 未发现安全漏洞

建议： 存在0个安全漏洞。本次修改实际上是安全加固，防止了空指针解引用导致的程序崩溃。无需额外安全加固。

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💡 改进建议代码示例

// 修复后的代码（src/editor/dtextedit.cpp，updateViewModeActions 函数）
void TextEdit::updateViewModeActions(ViewMode mode, bool isMarkdown)
{
    // ... 前置逻辑 ...
    if (action && !action->isChecked())
        action->setChecked(true);
    // 置灰规则（§4.4）：非 md 文件仅「实时预览」置灰，编辑/查看始终可用
    if (m_actLivePreview)  // 新增：空指针检查
        m_actLivePreview->setEnabled(isMarkdown);
}

// 修复说明：
// m_actLivePreview 初始化为 nullptr，仅在 initRightClickedMenu() 中赋值。
// updateViewModeActions() 可通过 signal/slot 在初始化前被调用，
// 添加空指针检查防止崩溃，与同函数已有的空安全模式一致。

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