[英]Make QWidget transparent
I have a QWidget
-based overlay widget which should paint some text and take place over the central widget of my application. 我有一个基于QWidget
的覆盖小部件,它应该绘制一些文本,并在我的应用程序的中央小部件上进行。 The problem is that I can't set background of overlay widget to be transparent. 问题是我无法将叠加小部件的背景设置为透明。 What I already tried: 我已经尝试过的:
setPalette(Qt::transparent);
setAttribute( Qt::WA_TranslucentBackground, true );
setAttribute( Qt::WA_OpaquePaintEvent, true );
setAutoFillBackground(false);
setStyleSheet("QWidget{background-color: transparent;}");
setAttribute(Qt::WA_NoSystemBackground);
My best guess to show an overlay widget, is convert the widget to a window, resize it to it's contents and move them to the desired position manually. 我最好的猜测是显示一个叠加小部件,将窗口小部件转换为窗口,将其大小调整为内容并手动将它们移动到所需位置。
MainWindow Example, showing the overlay widget in the center of the video widget: MainWindow示例,在视频小部件的中心显示重叠小部件:
Mwindow::Mwindow()
{
widget = new Widget(this);
}
void Mwindow::widgetSizeMove()
{
if (widget->width() <= videoWidget->width() && widget->height() <= videoWidget->height())
{
widget->setWindowOpacity(1); // Show the widget
QPoint p = videoWidget->mapToGlobal(videoWidget->pos());
int x = p.x() + (videoWidget->width() - widget->width()) / 2;
int y = p.y() + (videoWidget->height() - widget->height()) / 2;
widget->move(x, y);
widget->raise();
}
else
{
widget->setWindowOpacity(0); // Hide the widget
}
}
bool Mwindow::event(QEvent *event)
{
switch (event->type())
{
case QEvent::Show:
widget->show();
QTimer::singleShot(50, this, SLOT(widgetSizeMove()));
//Wait until the Main Window be shown
break;
case QEvent::WindowActivate:
case QEvent::Resize:
case QEvent::Move:
widgetSizeMove();
break;
default:
break;
}
return QMainWindow::event(event);
}
Widget Example: 小部件示例:
Widget::Widget(QWidget *parent) : QWidget(parent)
{
setWindowFlags(Qt::Window | Qt::FramelessWindowHint);
setAttribute(Qt::WA_NoSystemBackground);
setAttribute(Qt::WA_TranslucentBackground);
setAttribute(Qt::WA_PaintOnScreen);
setAttribute(Qt::WA_TransparentForMouseEvents);
}
void Widget::paintEvent(QPaintEvent*)
{
QPainter p(this);
QString text = "Some foo goes here";
QFontMetrics metrics(p.font());
resize(metrics.size(0, text));
p.drawText(rect(), Qt::AlignCenter, text);
}
Example when showing a video with LibVLC: 使用LibVLC显示视频时的示例:
最佳解决方案由GökmenGöksel在本文的一篇评论中提供
setStyleSheet("background-color: rgba(0,0,0,0)");
On Linux works with: 在Linux上使用:
setWindowFlags(Qt::FramelessWindowHint);
setAttribute(Qt::WA_NoSystemBackground);
setAttribute(Qt::WA_TranslucentBackground);
setAttribute(Qt::WA_TransparentForMouseEvents);
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