#include <CtrlLib/CtrlLib.h>

using namespace Upp;

Tuple2<int, int> GetVisibleRange(const ArrayCtrl& array)
{
	int from, to;
	const int last = array.GetCount() - 1;

	if (last >= 0) {
		const int cy = array.GetSize().cy - 1,
			sb = array.GetScroll();

		from = array.GetLineAt(sb),
		to = array.GetLineY(last) <= cy ? last : array.GetLineAt(sb + cy);
	}
	if (last < 0 || IsNull(to) || from > to)
		from = to = -1;

	return MakeTuple(from, to);
}

class App : public TopWindow {
public:
	typedef App CLASSNAME;
	App();

	ArrayCtrl list;
	DropList dropCount;

	void OnGet();
	void OnSelect();
};

App::App()
{
	Title(t_("The visible range of rows for ArrayCtrl"));
	Sizeable().Zoomable();
	SetRect(Size(640, 480));

	list.AddRowNumColumn("Index").SetDisplay(StdCenterDisplay()).HeaderTab().SetAlign(ALIGN_CENTER);
	const int count = 0x100000;
	list.SetVirtualCount(count);

	dropCount.AddButton().SetLabel(t_("Get")).Tip(t_("Get the visible range of rows")).Left().WhenPush = THISBACK(OnGet);
	dropCount.SetDisplay(StdCenterDisplay()).WhenAction = THISBACK(OnSelect);
	dropCount.Add(0, t_("Empty"))
		.Add(10, 10)
		.Add(count, count)
		.SetIndex(2);

	Add(list.HSizePosZ(4, 4).VSizePosZ(4, 28));
	Add(dropCount.HCenterPosZ(100).BottomPosZ(4, 20));
}

void App::OnSelect()
{
	const int index = dropCount.GetIndex();
	if (index < 0)
		return;

	list.SetVirtualCount(dropCount.GetKey(index));
}

void App::OnGet()
{
	Tuple2<int, int> range = GetVisibleRange(list);

	PromptOK(range.b < 0 ?
		t_("The rows are not visible") :
		NFormat(t_("From %d to %d"), range.a, range.b));
/*	// How to use the result:
	RDUMP(range);
	if (range.b >= 0)
		for (int i = range.a; i <= range.b; ++i)
			RLOG(i << ": " << list.Get(i, 0));
*/
}

GUI_APP_MAIN
{
	Ctrl::GlobalBackPaint();

	App app;
	app.Run();
}