Mercurial > hg > svgui
view widgets/WidgetScale.h @ 1271:d967e21fe995
Avoid crash when scrolling with an empty layer open
author | Chris Cannam |
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date | Mon, 23 Apr 2018 16:04:51 +0100 |
parents | be5e43e2180c |
children | e7c9650e74a7 |
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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */ /* Sonic Visualiser An audio file viewer and annotation editor. Centre for Digital Music, Queen Mary, University of London. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. See the file COPYING included with this distribution for more information. */ #ifndef SV_WIDGET_SCALE_H #define SV_WIDGET_SCALE_H #include <QFont> #include <QFontMetrics> #include "base/Debug.h" class WidgetScale { public: /** * Take a "design pixel" size and scale it for the actual * display. This is relevant to hi-dpi systems that do not do * pixel doubling (i.e. Windows and Linux rather than OS/X). */ static int scalePixelSize(int pixels) { static double ratio = 0.0; if (ratio == 0.0) { double baseEm; #ifdef Q_OS_MAC baseEm = 17.0; #else baseEm = 15.0; #endif double em = QFontMetrics(QFont()).height(); ratio = em / baseEm; SVDEBUG << "WidgetScale::scalePixelSize: baseEm = " << baseEm << ", platform default font height = " << em << ", resulting scale factor = " << ratio << endl; } int scaled = int(pixels * ratio + 0.5); if (pixels != 0 && scaled == 0) scaled = 1; return scaled; } static QSize scaleQSize(QSize size) { return QSize(scalePixelSize(size.width()), scalePixelSize(size.height())); } }; #endif