diff options
| -rw-r--r-- | profile-widget/qmlprofile.cpp | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/profile-widget/qmlprofile.cpp b/profile-widget/qmlprofile.cpp index 733ee4633..08f5836af 100644 --- a/profile-widget/qmlprofile.cpp +++ b/profile-widget/qmlprofile.cpp @@ -62,6 +62,25 @@ void QMLProfile::paint(QPainter *painter) // shift the painter (taking its existing transformation into account) QTransform profileTransform = QTransform(); profileTransform.scale(sx, sy); + + // this is a bit complex because of the interaction with the Qt widget scaling + // logic. We use the default setup where the scale happens with the center of the + // widget as transformation center. + // The QML code *should* already ensure that we don't shrink the profile, but for + // the math below to work, let's make sure + qreal profileScale = scale(); + if (profileScale < 1.0) { + profileScale = 1.0; + setScale(profileScale); + } + // When zooming and panning we want to ensure that we always show a subset of the + // profile and not the "empty space" around the profile. + // a bit of math on a piece of paper shows that our offsets need to stay within +/- dx and dy + qreal dx = width() * (profileScale - 1) / (2 * dpr * profileScale); + qreal dy = height() * (profileScale - 1) / (2 * dpr * profileScale); + m_xOffset = std::max(-dx, std::min(m_xOffset, dx)); + m_yOffset = std::max(-dy, std::min(m_yOffset, dy)); + QTransform painterTransform = painter->transform(); painterTransform.translate(dpr * m_xOffset - painterRect.width() * magicShiftFactor, dpr * m_yOffset - painterRect.height() * magicShiftFactor); |