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Restrict drag&drop to one level [message #25209]

Sun, 14 February 2010 11:14

dolik.rce
Messages: 1789
Registered: August 2008
Location: Czech Republic

Ultimate Contributor

Hello!

I've got a little problem here. I want to have a TreeCtrl with drag and drop implemented in such a way, that items from one level can not be inserted into different level. An example to illustrate:

+ Graphs
  + Graph1
  | + Data1
  | + Data2
  + Graph2
    + Data3

I need to allow user to drag any Data into any Graph and disable dropping it into any other level. Also, any Graph must not be dropped anywhere else then top level.

I think this is quite common situation, so there should be easy solution. I'm probably just missing something Smile

Bellow is the code I got so far, but it has two problems. First, it doesn't work properly with MultiSelect(). Second, it paints insert marks even in positions where drop is not allowed, which might confuse user. I hope someone can give me some hint how to solve this. The code:

#include "CtrlLib/CtrlLib.h"
using namespace Upp;

struct App : TopWindow {
	typedef App CLASSNAME;
	TreeCtrl   tree;

	void DropInsert(int parent, int ii, PasteClip& d){
		if(AcceptInternal<TreeCtrl>(d, "graph")) {
			if(GetLevel(parent)!=0) {d.Reject();return;}
			tree.InsertDrop(parent, ii, d);
			tree.SetFocus();
			LOG("accepted graph");
			return;
		}
		if(AcceptInternal<TreeCtrl>(d, "data")) {
			if(GetLevel(parent)!=1) {d.Reject();return;}
			tree.InsertDrop(parent, ii, d);
			tree.SetFocus();
			LOG("Accepted series");
			return;
		}
	}

	void Drag()	{
		int type=GetLevel(tree.GetCursor());
		switch(type) {
		case 1:
			if(tree.DoDragAndDrop(InternalClip(tree, "graph"),tree.GetDragSample()) == DND_MOVE)
				tree.RemoveSelection();
			break;
		case 2:
			if(tree.DoDragAndDrop(InternalClip(tree, "data"),tree.GetDragSample()) == DND_MOVE)
				tree.RemoveSelection();
			break;
		}
	}
	
	int GetLevel(int id){
		int i=0;
		while(id!=0){
			id=tree.GetParent(id);
			i++;
		}
		return i;
	}
	
	App() {
		Add(tree.SizePos());
		tree.SetRoot(Image(), "Graphs");
		for(int i=1;i<3;i++){
			int id=tree.Add(0,Image(),"Graph "+AsString(i));
			for(int j=1;j<3;j++)
				tree.Add(id,Image(),"Data "+AsString(i)+"/"+AsString(j));
		}
		tree.OpenDeep(0);
		tree.WhenDropInsert = THISBACK(DropInsert);
		tree.WhenDrag = THISBACK(Drag);
		tree.MultiSelect();
		Sizeable();
	}
};

GUI_APP_MAIN
{
	App().Run();
}

Best regards,
Honza

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