KonvergoWindow: improve web scale factor notification handling

Strictly call it if any of those change. I'm not entirely sure how their
relation is, but maybe it's good if the code doesn't have to care about
it. Also, cache the result, instead of possibly computing inconsistent
in-between values of it (e.g. during resizing). This makes sense
especially because notifyScale() gets a special size value as argument,
that apparently doesn't have to be the same as the window's size().

src/ui/KonvergoWindow.cpp

@@ -25,7 +25,7 @@
 KonvergoWindow::KonvergoWindow(QWindow* parent) :
   QQuickWindow(parent),
   m_debugLayer(false),
-  m_lastScale(1.0),
+  m_lastWindowScale(-1), m_lastWebScale(-1),
   m_ignoreFullscreenSettingsChange(0),
   m_showedUpdateDialog(false),
   m_osxPresentationOptions(0)
@@ -622,15 +622,17 @@ void KonvergoWindow::toggleDebug()
 /////////////////////////////////////////////////////////////////////////////////////////
 void KonvergoWindow::notifyScale(const QSize& size)
 {
-  qreal scale = CalculateScale(size);
-  if (scale != m_lastScale)
+  qreal windowScale = CalculateScale(size);
+  qreal webScale = CalculateWebScale(size, devicePixelRatio());
+  if (windowScale != m_lastWindowScale || webScale != m_lastWebScale)
   {
-    QLOG_DEBUG() << "windowScale updated to:" << scale << "webscale:" << CalculateWebScale(size, devicePixelRatio());
-    m_lastScale = scale;
+    QLOG_DEBUG() << "windowScale updated to:" << windowScale << "webscale:" << webScale;
 
-    emit SystemComponent::Get().scaleChanged(CalculateWebScale(size, devicePixelRatio()));
+    m_lastWindowScale = windowScale;
+    m_lastWebScale = webScale;
+    emit SystemComponent::Get().scaleChanged(webScale);
+    emit webScaleChanged();
   }
-  emit webScaleChanged();
 }
 
 /////////////////////////////////////////////////////////////////////////////////////////

src/ui/KonvergoWindow.h

@@ -91,12 +91,10 @@ public:
       setVisibility(QWindow::Minimized);
   }
 
-  qreal windowScale() { return CalculateScale(size()); }
-  qreal webScale() { return CalculateWebScale(size(), devicePixelRatio()); }
+  qreal windowScale() { return m_lastWindowScale; }
+  qreal webScale() { return m_lastWebScale; }
   qreal webHeightMax() { return WEBUI_MAX_HEIGHT; }
   QSize windowMinSize() { return WINDOWW_MIN_SIZE; }
-  static qreal CalculateScale(const QSize& size);
-  static qreal CalculateWebScale(const QSize& size, qreal devicePixelRatio);
   QString webUrl();
 
   qreal webUIWidth()
@@ -152,7 +150,7 @@ private:
   QScreen* findCurrentScreen();
 
   bool m_debugLayer;
-  qreal m_lastScale;
+  qreal m_lastWindowScale, m_lastWebScale;
   QTimer* m_infoTimer;
   QString m_debugInfo, m_systemDebugInfo, m_videoInfo;
   int m_ignoreFullscreenSettingsChange;
@@ -163,6 +161,9 @@ private:
   QString m_currentScreenName;
 
   void setWebMode(bool newDesktopMode, bool fullscreen);
+
+  static qreal CalculateScale(const QSize& size);
+  static qreal CalculateWebScale(const QSize& size, qreal devicePixelRatio);
 };
 
 #endif // KONVERGOWINDOW_H