Enhancements for zooming of PDF document (related to 204).

src/board/UBBoardController.cpp

@@ -1519,6 +1519,10 @@ void UBBoardController::updateSystemScaleFactor()
     if (mActiveScene)
     {
         QSize pageNominalSize = mActiveScene->nominalSize();
+		//we're going to keep scale factor untouched if the size is custom
+		QMap<DocumentSizeRatio::Enum, QSize> sizesMap = UBSettings::settings()->documentSizes;
+		if(pageNominalSize == sizesMap.value(DocumentSizeRatio::Ratio16_9) || pageNominalSize == sizesMap.value(DocumentSizeRatio::Ratio4_3))
+		{
 			QSize controlSize = controlViewport();
 
 			qreal hFactor = ((qreal)controlSize.width()) / ((qreal)pageNominalSize.width());
@@ -1526,6 +1530,7 @@ void UBBoardController::updateSystemScaleFactor()
 
 			newScaleFactor = qMin(hFactor, vFactor);
 		}
+    }
 
     if (mSystemScaleFactor != newScaleFactor)
     {
@@ -1543,7 +1548,6 @@ void UBBoardController::updateSystemScaleFactor()
     mControlView->setTransform(scalingTransform);
     mControlView->horizontalScrollBar()->setValue(viewState.horizontalPosition);
     mControlView->verticalScrollBar()->setValue(viewState.verticalPostition);
-
 }