How to Change the Background Color of QWidget: Difference between revisions

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==Introduction==


'''English''' | [[How_to_Change_the_Background_Color_of_QWidget_German|Deutsch]] | [[How_to_Change_the_Background_Color_of_QWidget_Bulgarian|Български]] | [[How_to_Change_the_Background_Color_of_QWidget_Japanese|日本語]] | [[How_to_Change_the_Background_Color_of_QWidget_Spanish|Español]] | [[How_to_Change_the_Background_Color_of_QWidget_SimplifiedChinese|简体中文]]| [[How_to_Change_the_Background_Color_of_QWidget_Persian|Persian]]
{{DocLink|QWidget}} is the base class of all user interface objects which means that the same approaches for changing the background color can be used with them too.
 
= How to Change the Background Color of QWidget =


"QWidget":http://doc.qt.io/qt-5.0/qtwidgets/qwidget.html is the base class of all user interface objects which means that the same approaches for changing the background color can be used with them too.
==Using the Palette==


== Using the Palette ==
The first example demonstrates how to change the background color using {{DocLink|QPalette}}


The first example demonstrates how to change the background color using "QPalette":http://doc.qt.io/qt-5.0/qtgui/qpalette.html
<code>m_myWidget = new QWidget(this);
m_myWidget->setGeometry(0, 0, 300, 100);
QPalette pal = QPalette();


<code>
// set black background</code>
m_pMyWidget = new QWidget(this);
pal.setColor(QPalette::Window, Qt::black);
m_pMyWidget->setGeometry(0,0,300,100);
m_myWidget->setAutoFillBackground(true);
QPalette Pal(palette());
m_myWidget->setPalette(pal);
// set black background
m_myWidget->show();</code>
Pal.setColor(QPalette::Background, Qt::black);
m_pMyWidget->setAutoFillBackground(true);
m_pMyWidget->setPalette(Pal);
m_pMyWidget->show();
</code>


== Using Style Sheet ==
==Using Style Sheet==


The style sheet contains a textual description of customizations to the widget's style, as described in the "Qt Style Sheets document":http://doc.qt.io/qt-5.0/qtwidgets/stylesheet.html.
The style sheet contains a textual description of customizations to the widget's style, as described in the [http://doc.qt.io/qt-5/stylesheet.html Qt Style Sheets document].


<code>
<code>
m_pMyWidget = new QWidget(this);
m_myWidget = new QWidget(this);
m_pMyWidget->setGeometry(0,0,300,100);
m_myWidget->setGeometry(0, 0, 300, 100);
m_pMyWidget->setStyleSheet("background-color:black;");
m_myWidget->setStyleSheet("background-color:black;");
m_pMyWidget->show();
m_myWidget->show();
</code>
</code>


Both ways to change the background color of QWidget have been successfully built using Qt SDK 1.1 and tested on Symbian^3 devices.
Both ways to change the background color of QWidget have been successfully built using Qt SDK 1.1 and tested on Symbian devices.


'''Note:''' If you subclass a custom widget from QWidget, then in order to use the StyleSheets you need to provide a paintEvent to the custom widget :
'''Note:''' If you subclass a custom widget from QWidget, then in order to use the StyleSheets you need to provide a paintEvent to the custom widget :


<code>void CustomWidget::paintEvent(QPaintEvent *)
<code>
{
void CustomWidget::paintEvent(QPaintEvent* event)
{
  QStyleOption opt;
  QStyleOption opt;
  opt.init(this);
  opt.init(this);
  QPainter p(this);
  QPainter p(this);
  style()->drawPrimitive(QStyle::PE_Widget, &amp;opt, &amp;p, this);
  style()->drawPrimitive(QStyle::PE_Widget, &opt, &p, this);
 
QWidget::paintEvent(event);
 
}
</code>

Revision as of 21:43, 7 August 2021

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Introduction

QWidget is the base class of all user interface objects which means that the same approaches for changing the background color can be used with them too.

Using the Palette

The first example demonstrates how to change the background color using QPalette 

m_myWidget = new QWidget(this);
m_myWidget->setGeometry(0, 0, 300, 100);
QPalette pal = QPalette();

// set black background

pal.setColor(QPalette::Window, Qt::black); m_myWidget->setAutoFillBackground(true); m_myWidget->setPalette(pal); m_myWidget->show();

Using Style Sheet

The style sheet contains a textual description of customizations to the widget's style, as described in the Qt Style Sheets document. 

m_myWidget = new QWidget(this);
m_myWidget->setGeometry(0, 0, 300, 100);
m_myWidget->setStyleSheet("background-color:black;");
m_myWidget->show();

Both ways to change the background color of QWidget have been successfully built using Qt SDK 1.1 and tested on Symbian devices.

Note: If you subclass a custom widget from QWidget, then in order to use the StyleSheets you need to provide a paintEvent to the custom widget : 

void CustomWidget::paintEvent(QPaintEvent* event)
{
 QStyleOption opt;
 opt.init(this);
 QPainter p(this);
 style()->drawPrimitive(QStyle::PE_Widget, &opt, &p, this);

 QWidget::paintEvent(event);

}
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