Fix warnings on the charts tab of summary screen

Engine.GetTextWidth has been deprecated since e845da025a

Idea:
If you look at a dropdown as just a text field (its header) that can
change caption like any other, then getPreferredHeaderTextSize is the
equivalent to getPreferredTextSize (present on buttons and text fields).

Fixes #8493

binaries/data/mods/public/gui/summary/summary.js

@@ -265,8 +265,8 @@ function initGUICharts()
 function resizeDropdown(dropdown)
 {
 	dropdown.size.bottom = dropdown.size.top +
-		(Engine.GetTextWidth(dropdown.font, dropdown.list[dropdown.selected]) >
-			dropdown.size.right - dropdown.size.left - 28 &&
+		(dropdown.getPreferredHeaderTextSize().width >
+			dropdown.size.right - dropdown.size.left - dropdown.button_width &&
 		    dropdown.list[dropdown.selected].indexOf(" ") !== -1 ? 42 : 28);
 }
 

source/gui/GUIObjectTypes.cpp

@@ -49,6 +49,7 @@ void CGUI::AddObjectTypes()
 	m_ProxyData.insert(JSI_GUIProxy<IGUIObject>::CreateData(*m_ScriptInterface));
 	m_ProxyData.insert(JSI_GUIProxy<CText>::CreateData(*m_ScriptInterface));
 	m_ProxyData.insert(JSI_GUIProxy<CList>::CreateData(*m_ScriptInterface));
+	m_ProxyData.insert(JSI_GUIProxy<CDropDown>::CreateData(*m_ScriptInterface));
 	m_ProxyData.insert(JSI_GUIProxy<CMiniMap>::CreateData(*m_ScriptInterface));
 	m_ProxyData.insert(JSI_GUIProxy<CButton>::CreateData(*m_ScriptInterface));
 	m_ProxyData.insert(JSI_GUIProxy<CScrollPanel>::CreateData(*m_ScriptInterface));

source/gui/ObjectTypes/CDropDown.cpp

@@ -34,6 +34,7 @@
 #include <algorithm>
 #include <cmath>
 #include <cstdlib>
+#include <limits>
 #include <vector>
 
 CDropDown::CDropDown(CGUI& pGUI)
@@ -501,3 +502,11 @@ float CDropDown::GetBufferedZ() const
 	else
 		return bz;
 }
+
+CSize2D CDropDown::GetPreferredHeaderTextSize() const
+{
+	if (m_Selected == -1)
+		return CSize2D{0.0f, 0.0f};
+
+	return CGUIText{m_pGUI, m_List->m_Items[m_Selected], m_Font, std::numeric_limits<float>::max(), m_BufferZone, m_TextAlign, this}.GetSize();
+}

source/gui/ObjectTypes/CDropDown.h

@@ -74,6 +74,8 @@ public:
 	 */
 	virtual void Draw(CCanvas2D& canvas);
 
+	virtual void CreateJSObject() override;
+
 	// This is one of the few classes we actually need to redefine this function
 	//  this is because the size of the control changes whether it is open
 	//  or closed.
@@ -81,6 +83,11 @@ public:
 
 	virtual float GetBufferedZ() const;
 
+	/**
+	 * Calculate the preferred text size of the currently selected item displayed in the header.
+	 */
+	virtual CSize2D GetPreferredHeaderTextSize() const;
+
 protected:
 	/**
 	 * If the size changed, the texts have to be updated as

source/gui/Scripting/JSInterface_GUIProxy.cpp

@@ -22,6 +22,7 @@
 
 #include "gui/ObjectBases/IGUIObject.h"
 #include "gui/ObjectTypes/CButton.h"
+#include "gui/ObjectTypes/CDropDown.h"
 #include "gui/ObjectTypes/CList.h"
 #include "gui/ObjectTypes/CMiniMap.h"
 #include "gui/ObjectTypes/CScrollPanel.h"
@@ -69,6 +70,13 @@ template<> void JSI_GUIProxy<CList>::CreateFunctions(const ScriptRequest& rq, GU
 }
 DECLARE_GUIPROXY(CList);
 
+// CDropDown
+template<> void JSI_GUIProxy<CDropDown>::CreateFunctions(const ScriptRequest& rq, GUIProxyProps* cache)
+{
+	CreateFunction<&CDropDown::GetPreferredHeaderTextSize>(rq, cache, "getPreferredHeaderTextSize");
+}
+DECLARE_GUIPROXY(CDropDown);
+
 // CMiniMap
 template<> void JSI_GUIProxy<CMiniMap>::CreateFunctions(const ScriptRequest& rq, GUIProxyProps* cache)
 {