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Home » U++ Library support » ArrayCtrl, HeaderCtrl & GridCtrl » Problem - GridCtrl::Get(int,int) with DropTree
Problem - GridCtrl::Get(int,int) with DropTree [message #26816] Mon, 31 May 2010 05:25 Go to next message
ktj9 is currently offline  ktj9
Messages: 17
Registered: April 2010
Promising Member
I am using DropTree as editing widget for a column in GridCtrl. However, I do not restrict the uniqueness of items in DropTree. So I better get the cursor or key from DropTree. But it seems impossible without changes.

GridCtrl activates widgets on editing, and holds Value when inactivates. GridCtrl set DropTree cursor upon editing using the Value it holds and let DropTree set cursor by finding the Value, not the key. If I use GetCtrl member function, GridCtrl returns the only DropTree it has, and the state is actually useless for particular cell.

I can see a hacking to resolve my problem, by using dynamic casting to check whether the widget is DropTree and do special things if it is. But it is certainly not a general solution.

I am wondering whether there are any other better thoughts on the issue.

Thanks!
Re: Problem - GridCtrl::Get(int,int) with DropTree [message #26827 is a reply to message #26816] Tue, 01 June 2010 00:18 Go to previous message
ktj9 is currently offline  ktj9
Messages: 17
Registered: April 2010
Promising Member
As I said, the problem could be solved by changing GridCtrl source (using dynamic casting to peek DropTree type then do special setting and getting). But the is certainly not a good general solution.

I am trying another solution: define a new Value type that holds both String representation and key/cursor information; derive from DropTree, and the subclass handles the new type in setter and getter. It turns out to be a big exercise of customize Value type. Though Value is supposed to be easy to use, but extending/customizing it is not very fun, at least in this situation. Though I am approaching solving the problem, there are still things are missing that I don't understand. For example, I have to create dummy member functions (see codes below) that basically do nothing but just let templates compile.

Any way, here is my current solution: instead of using DropTree directly, use DropTreeForGridCtrl defined below:


class StringWithKey {
	String	_s;
	int		_key;
public:
	StringWithKey(){}
	StringWithKey(const String& s, int k)
	:_s(s),_key(k)
	{}
	virtual ~StringWithKey(){}
	StringWithKey& operator=(const StringWithKey& rhs)
	{
		if (&rhs==this)
			return *this;
		_s=rhs._s;
		_key=rhs._key;
		return *this;
	}
	StringWithKey& operator=(const Value& rhs)
	{
		return *this;
	}
	StringWithKey& operator<<=(const StringWithKey& rhs)
	{
		return this->operator=(rhs);
	}
	bool operator==(const StringWithKey& rhs) const
	{
		return rhs._key==_key && rhs._s==_s;
	}
	virtual bool       IsEqual(const Value::Void *p)
	{
		const StringWithKey* rhs=dynamic_cast<const StringWithKey*>(p);
		if (!rhs)
			return false;
		return operator==(*rhs);
	}
	int  GetKey() const 
	{ 
		return _key; 
	}
	StringWithKey& SetKey(int key) 
	{ 
		_key=key; 
		return *this; 
	}
	virtual String AsString() const
	{
		return _s;
	}
	virtual String ToString() const
	{
		return _s;
	}
	virtual dword      GetType() const
	{
		return STRING_V;
	}
	virtual bool       IsNull() const
	{ 
		return false;
	}
	bool IsNullInstance() const 
	{
		return false;
	}
	void Serialize(Stream& s)
	{
	}
	unsigned GetHashValue() const
	{
		return 0;
	}
};

class DropTreeForGridCtrl : public DropTree {
	mutable StringWithKey	_value;
public:
	DropTreeForGridCtrl(){}
	virtual ~DropTreeForGridCtrl(){}
	virtual void  SetData(const Value& data)
	{
		if (!dynamic_cast<const RichValueRep<StringWithKey>*>(data.GetVoidPtr()))
			return;
		StringWithKey t = dynamic_cast<const RichValueRep<StringWithKey>*>(data.GetVoidPtr())->Get();
		_value=t;
		TreeObject().SetCursor(_value.GetKey());
	}
	virtual Value GetData() const 
	{
		_value = StringWithKey(
			const_cast<DropTreeForGridCtrl&>(*this).TreeObject().GetData(),
			const_cast<DropTreeForGridCtrl&>(*this).TreeObject().GetCursor());
		Value ret(new RichValueRep<StringWithKey>(_value));
		return ret; 
	}
};

[Updated on: Tue, 01 June 2010 03:28]

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