Toplevel widget with rounded corners.

[munna]

Hi,

I have a QWidget (frameless) as my mainwindow. I want it to have rounded corners. Is there a way other than setMask() to make the corners rounded ?

Thanks.

[zlatko]

What make you think that setMask() is bad way ?

[munna]

I did not say it is a bad way, I was just hoping that there might be a better and simpler way to do this.

Assuming that I use the setMask way, can you please give me a sample where i don't have to use an external image in order to set the mask.

Thanks a lot.

[jpn]

Assuming that I use the setMask way, can you please give me a sample where i don't have to use an external image in order to set the mask.

Notice that QWidget has 2 overloads of setMask(). One takes QBitmap and another takes QRegion. A QRegion's RegionType can be ellipse. A large enough ellipse clips corners of a rectangle and gives a rounded rectangle..

[munna]

Thanks for replying

A QRegion's RegionType can be ellipse. A large enough ellipse clips corners of a rectangle and gives a rounded rectangle

I see your point but the problem is that I am having a square widget. This will always give a circular widget and not rounded corners.

Is it possible to subtract four small circles from the rectangle of the widget and then set the mask ?

[jacek]

Is it possible to subtract four small circles from the rectangle of the widget and then set the mask ?

QRegion::subtract()

[jpn]

Is it possible to subtract four small circles from the rectangle of the widget and then set the mask ?

You cannot substract the circles, you will end up having holes in the corners.
This should help unless you already solved the prob

static QRegion roundedRect(const QRect& rect, int r)
{
	QRegion region;
	// middle and borders
	region += rect.adjusted(r, 0, -r, 0);
	region += rect.adjusted(0, r, 0, -r);
	// top left
	QRect corner(rect.topLeft(), QSize(r*2, r*2));
	region += QRegion(corner, QRegion::Ellipse);
	// top right
	corner.moveTopRight(rect.topRight());
	region += QRegion(corner, QRegion::Ellipse);
	// bottom left
	corner.moveBottomLeft(rect.bottomLeft());
	region += QRegion(corner, QRegion::Ellipse);
	// bottom right
	corner.moveBottomRight(rect.bottomRight());
	region += QRegion(corner, QRegion::Ellipse);
	return region;
}
 
someWidget->setMask(roundedRect(someWidget->rect(), 20));

static QRegion roundedRect(const QRect& rect, int r)
{
	QRegion region;
	// middle and borders
	region += rect.adjusted(r, 0, -r, 0);
	region += rect.adjusted(0, r, 0, -r);
	// top left
	QRect corner(rect.topLeft(), QSize(r*2, r*2));
	region += QRegion(corner, QRegion::Ellipse);
	// top right
	corner.moveTopRight(rect.topRight());
	region += QRegion(corner, QRegion::Ellipse);
	// bottom left
	corner.moveBottomLeft(rect.bottomLeft());
	region += QRegion(corner, QRegion::Ellipse);
	// bottom right
	corner.moveBottomRight(rect.bottomRight());
	region += QRegion(corner, QRegion::Ellipse);
	return region;
}

someWidget->setMask(roundedRect(someWidget->rect(), 20));

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[jpn]

Or yet better, I think:

void RoundedWidget::resizeEvent(QResizeEvent* event)
{
	QPixmap pixmap(size());
	QPainter painter(&pixmap);
	painter.fillRect(pixmap.rect(), Qt::white);
	painter.setBrush(Qt::black);
	painter.drawRoundRect(pixmap.rect());
	setMask(pixmap.createMaskFromColor(Qt::white));
}

void RoundedWidget::resizeEvent(QResizeEvent* event)
{
	QPixmap pixmap(size());
	QPainter painter(&pixmap);
	painter.fillRect(pixmap.rect(), Qt::white);
	painter.setBrush(Qt::black);
	painter.drawRoundRect(pixmap.rect());
	setMask(pixmap.createMaskFromColor(Qt::white));
}

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