Chris@1174: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@1174: 
Chris@1174: /*
Chris@1174:     Sonic Visualiser
Chris@1174:     An audio file viewer and annotation editor.
Chris@1174:     Centre for Digital Music, Queen Mary, University of London.
Chris@1174:     
Chris@1174:     This program is free software; you can redistribute it and/or
Chris@1174:     modify it under the terms of the GNU General Public License as
Chris@1174:     published by the Free Software Foundation; either version 2 of the
Chris@1174:     License, or (at your option) any later version.  See the file
Chris@1174:     COPYING included with this distribution for more information.
Chris@1174: */
Chris@1174: 
Chris@1174: #ifndef SV_WIDGET_SCALE_H
Chris@1174: #define SV_WIDGET_SCALE_H
Chris@1174: 
Chris@1174: #include <QFont>
Chris@1174: #include <QFontMetrics>
Chris@1174: 
Chris@1194: #include "base/Debug.h"
Chris@1194: 
Chris@1174: class WidgetScale
Chris@1174: {
Chris@1174: public:   
Chris@1174:     /**
Chris@1174:      * Take a "design pixel" size and scale it for the actual
Chris@1174:      * display. This is relevant to hi-dpi systems that do not do
Chris@1174:      * pixel doubling (i.e. Windows and Linux rather than OS/X).
Chris@1174:      */
Chris@1174:     static int scalePixelSize(int pixels) {
Chris@1174: 
Chris@1174:         static double ratio = 0.0;
Chris@1174:         if (ratio == 0.0) {
Chris@1174:             double baseEm;
Chris@1174: #ifdef Q_OS_MAC
Chris@1174:             baseEm = 17.0;
Chris@1174: #else
Chris@1174:             baseEm = 15.0;
Chris@1174: #endif
Chris@1174:             double em = QFontMetrics(QFont()).height();
Chris@1174:             ratio = em / baseEm;
Chris@1194:             SVDEBUG << "WidgetScale::scalePixelSize: baseEm = " << baseEm
Chris@1194:                     << ", platform default font height = " << em
Chris@1194:                     << ", resulting scale factor = " << ratio << endl;
Chris@1174:         }
Chris@1174: 
Chris@1174:         int scaled = int(pixels * ratio + 0.5);
Chris@1174:         if (pixels != 0 && scaled == 0) scaled = 1;
Chris@1174:         return scaled;
Chris@1174:     }
Chris@1174: 
Chris@1174:     static QSize scaleQSize(QSize size) {
Chris@1174:         return QSize(scalePixelSize(size.width()),
Chris@1174:                      scalePixelSize(size.height()));
Chris@1174:     }
Chris@1174: };
Chris@1174: 
Chris@1174: #endif