QML UI: take device pixel ratio into account when scaling pixmaps on iOS

This way warning icons and tank change icons and other event markers are no
longer ridiculously tiny on retina screens. Oddly this doesn't appear to be
needed on Android, only on iOS.

Fixes #1033

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

profile-widget/diveeventitem.cpp

@@ -65,8 +65,13 @@ void DiveEventItem::setupPixmap()
 	const IconMetrics& metrics = defaultIconMetrics();
 #ifndef SUBSURFACE_MOBILE
 	int sz_bigger = metrics.sz_med + metrics.sz_small; // ex 40px
+#else
+#if defined(Q_OS_IOS)
+	 // on iOS devices we need to adjust for Device Pixel Ratio
+	int sz_bigger = metrics.sz_med  * metrics.dpr;
 #else
 	int sz_bigger = metrics.sz_med;
+#endif
 #endif
 	int sz_pix = sz_bigger/2; // ex 20px
 

qt-mobile/qmlprofile.cpp

@@ -2,6 +2,7 @@
 #include "qmlmanager.h"
 #include "profile-widget/profilewidget2.h"
 #include "subsurface-core/dive.h"
+#include "subsurface-core/metrics.h"
 #include <QTransform>
 #include <QScreen>
 
@@ -99,6 +100,7 @@ void QMLProfile::setDevicePixelRatio(qreal dpr)
 	if (dpr != m_devicePixelRatio) {
 		m_devicePixelRatio = dpr;
 		m_profileWidget->setFontPrintScale(0.8 * dpr);
+		updateDevicePixelRatio(dpr);
 		emit devicePixelRatioChanged();
 	}
 }

subsurface-core/metrics.cpp

@@ -15,7 +15,8 @@ IconMetrics::IconMetrics() :
 	sz_med(-1),
 	sz_big(-1),
 	sz_pic(-1),
-	spacing(-1)
+	spacing(-1),
+	dpr(1.0)
 {
 }
 
@@ -57,3 +58,8 @@ const IconMetrics & defaultIconMetrics()
 
 	return dfltIconMetrics;
 }
+
+void updateDevicePixelRatio(double dpr)
+{
+	dfltIconMetrics.dpr = dpr;
+}

subsurface-core/metrics.h

@@ -25,9 +25,12 @@ struct IconMetrics {
 	int sz_pic; // ex 128px
 	// icon spacing
 	int spacing; // ex 2px
+	// devicePixelRatio
+	double dpr; // 1.0 for traditional screens, HiDPI screens up to 3.0
 	IconMetrics();
 };
 
 const IconMetrics & defaultIconMetrics();
+void updateDevicePixelRatio(double dpr);
 
 #endif // METRICS_H