fix: placeholder text horizontalAlignment not work

[kegechen]

remove loader

[zccrs]

没有看到哪里有使用 horizontalAlignment 呀

[deepin-bot]

Doc Check bot
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[kegechen]

没有看到哪里有使用 horizontalAlignment 呀

主要是 placeholdertext updateAlignment时 parentitem转换失败。不需要单独设置这个 textfield 里面设置就可以。

TextField {
            placeholderText: qsTr("test here")
            horizontalAlignment: Text.AlignHCenter 
        }

void QQuickPlaceholderText::updateAlignment()
{
    if (QQuickTextInput *input = qobject_cast<QQuickTextInput *>(parentItem())) {  // QQuickLoader
        if (QQuickTextInputPrivate::get(input)->hAlignImplicit)
            resetHAlign();
        else
            setHAlign(static_cast<HAlignment>(input->hAlign()));
    } else if (QQuickTextEdit *edit = qobject_cast<QQuickTextEdit *>(parentItem())) { // QQuickLoader
        if (QQuickTextEditPrivate::get(edit)->hAlignImplicit)
            resetHAlign();
        else
            setHAlign(static_cast<HAlignment>(edit->hAlign()));
    } else {
        resetHAlign();
    }
}

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[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: kegechen

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

Needs approval from an approver in each of these files:

• debian/deepin/OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[deepin-ci-robot]

deepin pr auto review

关键摘要:

• 移除了Loader组件，改为使用PlaceholderText，这可能会影响性能，需要确认是否有必要。
• 移除了signal effectiveHorizontalAlignmentChanged，需要确认这一改动是否会影响其他依赖此信号的代码部分。
• 修改了PlaceholderText组件的visible属性，这可能会影响用户界面，需要确保这是预期的行为。

是否建议立即修改:

• 是，需要确保性能和依赖关系的改动不会引入新的问题。
• 是，如果移除signal effectiveHorizontalAlignmentChanged会影响其他代码部分，应该立即修复。
• 是，如果PlaceholderText组件的visible属性改动未经过充分测试，应该立即进行测试以确保用户界面的正确性。

[zccrs]

这里可以写清楚，QQuickPlaceholderText 会假定他的 parent item 是 QQuickText，用了 Loader 会影响它的 parentItem