Add a GetTextSize() method to GUI objects

Usage:
  let size = Engine.GetGUIObjectByName({gui_object_name}).GetTextSize()

Returns a JS object containing the height and width of the primary text
field within
the object, taking into account new lines, text wrapping, and font
changes.

Unless the object doesn't contain text, in which case the method will
return undefined.

Commented on by: vladislavbelov
Additional code by: elexis
Reviewed By: wraitii
Differential Revision: https://code.wildfiregames.com/D844
This was SVN commit r22134.

source/gui/CGUI.cpp

@@ -1,4 +1,4 @@
-/* Copyright (C) 2018 Wildfire Games.
+/* Copyright (C) 2019 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -475,6 +475,15 @@ void CGUI::SetFocusedObject(IGUIObject* pObject)
 	}
 }
 
+const SGUIScrollBarStyle* CGUI::GetScrollBarStyle(const CStr& style) const
+{
+	std::map<CStr, SGUIScrollBarStyle>::const_iterator it = m_ScrollBarStyles.find(style);
+	if (it == m_ScrollBarStyles.end())
+		return nullptr;
+
+ 	return &it->second;
+}
+
 // private struct used only in GenerateText(...)
 struct SGenerateTextImage
 {
@@ -540,8 +549,9 @@ SGUIText CGUI::GenerateText(const CGUIString& string, const CStrW& FontW, const
 	// get the alignment type for the control we are computing the text for since
 	// we are computing the horizontal alignment in this method in order to not have
 	// to run through the TextCalls a second time in the CalculateTextPosition method again
-	EAlign align;
-	GUI<EAlign>::GetSetting(pObject, "text_align", align);
+	EAlign align = EAlign_Left;
+	if (pObject->SettingExists("text_align"))
+		GUI<EAlign>::GetSetting(pObject, "text_align", align);
 
 	// Go through string word by word
 	for (int i = 0; i < (int)string.m_Words.size()-1 && !done; ++i)