如何设置QComboBox按钮的背景颜色? [英] How to set background color of QComboBox button?

问题描述

版本/环境:

• Windows 10 64 位
• Qt 5.11.0 MSVC2017 64 位

我有一个简单的

现在我想改变按钮的背景颜色而不是选择的项目.

我的第一种方法是简单地使用 QWidget 的

我还使用了具有特定

仅使用 QComboBox {background: red;} 与使用 background-color: red; 的结果相同，只是选择的项目没有着色.

正如

我还尝试了几乎所有其他 QPalette

解决方案

QComboBox 自定义总是很棘手，因为它由子小部件(甚至是条件子小部件)组成.
我进行了测试，您的简单样式表 QComboBox {background:red} 在 Linux 上对我来说几乎可以正常工作，除了下拉框中的框边框也是红色的.行为似乎有所不同，具体取决于 GUI 风格.>

来自 doc:

<块引用>

注意:对于复杂的小部件，例如 QComboBox 和 QScrollBar，如果有自定义属性或子控件，所有其他属性或子控件也必须自定义.

如果您想自定义按钮，似乎您必须自定义所有内容......那么在不覆盖或抑制标准样式的情况下更改颜色是不可能的.

您可以设置整个下拉菜单的样式以模仿本机外观，但这样做并不好且不健壮(且不可移植).

QComboBox QAbstractItemView {边框:1px 纯灰色；背景:白色；选择背景颜色:蓝色；}QComboBox {背景:红色；}

Version/Environment:

• Windows 10 64 bit
• Qt 5.11.0 MSVC2017 64 bit

I have a simple QComboBox to enable/disable a feature:

QComboBox *onOffComboBox = new QComboBox();
onOffComboBox->insertItem(0, "Off");
onOffComboBox->insertItem(1, "On");

The combo box is added as a cell widget to a table:

this->ui->settingsTable->setCellWidget(rowNumber, 1, onOffComboBox);

Now i want to change the background color of the button but not the select items.

My first approach was simply to use QWidget's setStyleSheet function:

onOffComboBox->setStyleSheet("background-color: red;");

But this suppresses the standard style:

I also used variations with specific QComboBox styles according to the documentation:

onOffComboBox->setStyleSheet("QComboBox::drop-down {background: red;}");

But this only colors the part with the arrow and suppresses it's style:

Using just QComboBox {background: red;} has the same result as with background-color: red; just the select items are not colored.

Just as described in this answer another approach is to use QPallete:

QPalette pal = onOffComboBox->palette();
pal.setColor(QPalette::Base, QColor("red"));
onOffComboBox->setPalette(pal);
onOffComboBox->update(); // just in case this has any effect

This only colors the select items:

I also tried nearly all other QPalette color roles:

• QPalette::Window, QPalette::Foreground, QPalette::Button - do nothing
• QPalette::Base - colors the select items (see pic)
• QPalette::Text - colors the text of the button and the select items

So, how can i change the color of the QComboBox drop-down button background WITHOUT overwritting or suppressing the standard style?

The styles of the pop-up items also shouldn't change.

Here is an image of what i want:

解决方案

QComboBox is always tricky to customize because it is made of subwidgets (even conditional subwidgets).
I made tests and your simple stylesheet QComboBox {background:red} works almost fine for me on Linux, except that the box-border is also red in the dropdown. The behaviour seems to be different depending on the GUI style.

From the doc :

Note: With complex widgets such as QComboBox and QScrollBar, if one property or sub-control is customized, all the other properties or sub-controls must be customized as well.

It looks like you have to customize everything if you want to customize the button... Then it would not be possible to change the colour without overwriting or suppressing the standard style.

You could style the whole drop-down to mimic the native look, but it's not nice to do and not robust (and not portable).

QComboBox QAbstractItemView {
  border: 1px solid grey;
  background: white;
  selection-background-color: blue;
}
QComboBox {
  background: red;
}

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