xcb: round down the scale factor for values < 0.8

This solves huge UI on some (most ?) HD 13 inches that have
a calculated scale factor around 1.75.

Task-number: QTBUG-53022 QTBUG-57211
Change-Id: I6cc22d3e47d38cb1d5a0daf5646a936256664e48
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@qt.io>
This commit is contained in:
Mathieu Velten 2018-03-03 12:23:51 +01:00 committed by Aleix Pol Gonzalez
parent c1ead32a84
commit 23b139038a

View File

@ -750,7 +750,12 @@ void QXcbScreen::updateGeometry(const QRect &geometry, uint8_t rotation)
m_sizeMillimeters = sizeInMillimeters(geometry.size(), virtualDpi());
qreal dpi = geometry.width() / physicalSize().width() * qreal(25.4);
m_pixelDensity = qMax(1, qRound(dpi/96));
qreal rawFactor = dpi/96;
int roundedFactor = qFloor(rawFactor);
// Round up for .8 and higher. This favors "small UI" over "large UI".
if (rawFactor - roundedFactor >= 0.8)
roundedFactor = qCeil(rawFactor);
m_pixelDensity = qMax(1, roundedFactor);
m_geometry = geometry;
m_availableGeometry = geometry & m_virtualDesktop->workArea();
QWindowSystemInterface::handleScreenGeometryChange(QPlatformScreen::screen(), m_geometry, m_availableGeometry);