fix: correct default scale factor initialization

[mhduiy]

When the scale-factor setting from dconfig is invalid (<= 0), the code incorrectly used the invalid value to populate the "ALL" key in the ScaleFactors map. This would propagate an invalid scale factor (likely 0 or negative) to the system. The fix ensures that when no valid scale factor is configured, the recommendedScaleFactor parameter is used as the default value for all screens, providing a sensible fallback.

Log: Fixed an issue where an invalid display scale factor setting could cause incorrect scaling.

Influence:

1. Test display scaling when dconfig scale-factor is set to 0 or a negative value.
2. Verify that the recommended scale factor is applied correctly in such cases.
3. Ensure overall display scaling behavior remains consistent for valid settings.

fix: 修正默认缩放因子初始化错误

当从 dconfig 读取的 scale-factor 设置无效（<= 0）时，代码错误地使用了
该无效值来填充 ScaleFactors 映射中的 "ALL" 键。这会导致将无效的缩放因子
（可能为 0 或负数）传播到系统。此修复确保当没有配置有效的缩放因子时，使
用 recommendedScaleFactor 参数作为所有屏幕的默认值，提供了一个合理的回退
方案。

Log: 修复了无效的显示缩放因子设置可能导致缩放不正确的问题。

Influence:

1. 测试当 dconfig 的 scale-factor 设置为 0 或负值时的显示缩放。
2. 验证在此类情况下，推荐的缩放因子被正确应用。
3. 确保对于有效的设置，整体显示缩放行为保持一致。

PMS: BUG-345701

Summary by Sourcery

Bug Fixes:

• Prevent invalid (non-positive) configured scale-factor values from being propagated as the default scale factor by falling back to the recommended scale factor.

[deepin-ci-robot]

deepin pr auto review

我来对这个代码修改进行审查：

1. 语法逻辑：
   修改前的代码存在一个逻辑错误：当value <= 0时，将value（此时为无效值<=0）插入到map中，这显然是不合理的。修改后使用recommendedScaleFactor作为默认值是正确的，因为recommendedScaleFactor应该是一个有效的推荐缩放值。

2. 代码质量：

• 代码修改解决了原有的逻辑问题，提高了代码的可靠性。
• 变量命名清晰，"recommendedScaleFactor"和"value"的命名都很好地表达了其用途。
• 代码结构清晰，逻辑判断和处理步骤明确。

3. 代码性能：

• 这个修改不会对性能产生显著影响，只是改变了插入map的值。
• 建议可以考虑在value <= 0的情况下直接使用recommendedScaleFactor，避免不必要的value获取。

4. 代码安全：

• 修改后的代码更安全，避免了将无效的缩放值（<=0）设置到系统中。
• 建议可以添加对recommendedScaleFactor的有效性检查，确保它也是一个合理的正值。

改进建议：

1. 可以考虑添加对recommendedScaleFactor的有效性检查：

if (value <= 0 && recommendedScaleFactor > 0) {
    ScaleFactors map;
    map.insert("ALL", recommendedScaleFactor);
    setScreenScaleFactors(map, false);
}

2. 如果可能，建议将"ALL"定义为常量字符串，避免魔法字符串：

const QString ALL_SCREENS = "ALL";
// ...
map.insert(ALL_SCREENS, recommendedScaleFactor);

3. 考虑添加日志记录，便于调试和追踪：

qDebug() << "Setting scale factor for all screens to:" << recommendedScaleFactor;

总体来说，这个修改是必要的，它修复了一个可能导致系统使用无效缩放值的bug。修改后的代码更加合理和安全。

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Fixes default display scale factor initialization so that when an invalid dconfig scale-factor (<= 0) is read, the system falls back to the recommendedScaleFactor for all screens instead of propagating the invalid value.

Sequence diagram for fallback to recommended scale factor on invalid dconfig value

sequenceDiagram
    participant XSettingsManager
    participant DConfig
    participant DisplaySystem

    XSettingsManager->>DConfig: read_scale_factor
    DConfig-->>XSettingsManager: value
    XSettingsManager->>XSettingsManager: adjustScaleFactor recommendedScaleFactor
    alt value <= 0
        XSettingsManager->>XSettingsManager: set ALL scale factor = recommendedScaleFactor
        XSettingsManager->>DisplaySystem: setScreenScaleFactors map false
    else value > 0
        XSettingsManager->>XSettingsManager: use configured scale factor
        XSettingsManager->>DisplaySystem: apply configured scale factors
    end

Loading

Flow diagram for scale factor initialization logic

flowchart TD
    A[Read scale factor from dconfig] --> B{value <= 0}
    B -->|Yes| C[Create ScaleFactors map]
    C --> D[Insert ALL with recommendedScaleFactor]
    D --> E[Call setScreenScaleFactors map false]
    B -->|No| F[Use existing valid scale factor handling]

Loading

File-Level Changes

Change	Details	Files
Use recommendedScaleFactor as the default scale factor when dconfig scale-factor is invalid (<= 0).	Read scale-factor from dconfig and check if the value is less than or equal to zero. When the value is invalid, construct a ScaleFactors map with the "ALL" key set to recommendedScaleFactor instead of the invalid value. Call setScreenScaleFactors with the corrected map to ensure a sensible fallback scale factor is applied.	src/plugin-qt/xsettings/impl/xsettingsmanager.cpp

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[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: mhduiy, robertkill

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

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• debian/deepin/OWNERS

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[mhduiy]

/forcemerge

[deepin-bot]

This pr force merged! (status: blocked)