How to use C++ Qt QColorDialog

Qt provides a color selection box, as shown below:

 

How to use QColorDialog

For example, the following code, click the button to pop up the color selection box, select the color, and change the background color of QLabel

#include "widget.h"
#include "ui_widget.h"
#include <QColorDialog>
#include <QPalette>

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);

    ui->label->setText(u8"我是lable");
}

Widget::~Widget()
{
    delete ui;
}

void Widget::on_btn1_clicked()
{
    QColor color = QColorDialog::getColor(Qt::white, this, u8"选择颜色");
    if(color.isValid())
    {
        QPalette palette;
        palette.setColor(QPalette::Background ,color);
        ui->label->setAutoFillBackground(true);
        ui->label->setPalette(palette);
    }
}

The effect is as follows:

 

getColor call

getColor is declared as follows:

static QColor getColor(const QColor &initial = Qt::white,
                           QWidget *parent = nullptr,
                           const QString &title = QString(),
                           ColorDialogOptions options = ColorDialogOptions());

The first parameter is the default color. For example, in the above code, I set it directly to white. The
second parameter is the parent window pointer.
The third is the color dialog window title.

QPalette setColor

The declaration of setColor is as follows:

inline void QPalette::setColor(ColorRole acr, const QColor &acolor)

You can use the color returned by QColorDialog to directly construct a QPalette. Note that the first parameter of setColor needs a ColorRole, which can be referred to as follows:

enum ColorRole { WindowText, Button, Light, Midlight, Dark, Mid,
                     Text, BrightText, ButtonText, Base, Window, Shadow,
                     Highlight, HighlightedText,
                     Link, LinkVisited,
                     AlternateBase,
                     NoRole,
                     ToolTipBase, ToolTipText,
                     PlaceholderText,
                     NColorRoles = PlaceholderText + 1,
#if QT_DEPRECATED_SINCE(5, 13)
                     Foreground Q_DECL_ENUMERATOR_DEPRECATED_X("Use QPalette::WindowText instead") = WindowText,
                     Background Q_DECL_ENUMERATOR_DEPRECATED_X("Use QPalette::Window instead") = Window
#endif
                   };

For example, the above code is to modify the background color of Label, then you need to use the Background enumerator, and if you change the text, use Text.

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