SidebarLibrary.WinControls.OutlookBar.ProcessItemHit C# (CSharp) Method

		void ProcessItemHit(int index, Point pt)
		{
			bool itemPressed = true;
			Capture = true;
			using (Graphics g = Graphics.FromHwnd(Handle))
			{
				Rectangle itemRect = GetItemRect(g, bands[currentBandIndex], index, Rectangle.Empty);
				DrawItem(g, index, itemRect, true, true, Rectangle.Empty, null);
				bool dragging = false;
				int deltaX = 0;
				int deltaY = 0;
				bool itemHighlighted = false;
				int dragItemIndex = -1;

				bool doLoop = true;
				while (doLoop)
				{
					// Check messages until we find a condition to break out of the loop
					Win32.MSG msg = new Win32.MSG();
					WindowsAPI.GetMessage(ref msg, 0, 0, 0);
					Point point = new Point(0, 0);
					if (msg.message == (int)Msg.WM_MOUSEMOVE || msg.message == (int)Msg.WM_LBUTTONUP)
					{
						point = WindowsAPI.GetPointFromLPARAM((int)msg.lParam);
						if (msg.message == (int)Msg.WM_MOUSEMOVE)
						{
							deltaX = pt.X - point.X;
							deltaY = pt.Y - point.Y;
						}
					}

					switch (msg.message)
					{
						case (int)Msg.WM_MOUSEMOVE:
						{
							int currentIndex;
							HitTestType hit = HitTest(point, out currentIndex, dragging);
							if (dragging)
							{

								if (hit == HitTestType.DropLine || hit == HitTestType.DropLineLastItem)
								{
									Cursor.Current = dragCursor;
									// Draw the Dragline
									DrawDropLine(g, currentIndex, true, hit);
								}
								else
								{
									Cursor.Current = Cursors.No;
									// Erase the Dragline
									DrawDropLine(g, index, false, hit);
								}

								if (hit == HitTestType.Item && currentIndex == index)
								{
									if (itemHighlighted == false)
									{
										DrawItem(g, index, itemRect,
										true, false, Rectangle.Empty, null);
										itemHighlighted = true;
									}
								}
								else
								{
									if (hit == HitTestType.Item)
									{

										// Erase previous highlighting first
										if (itemHighlighted)
										{
											DrawItem(g, index, itemRect,
											false, false, Rectangle.Empty, null);
										}

										// Highlight new item
										itemRect = GetItemRect(g, bands[currentBandIndex], currentIndex, Rectangle.Empty);
										index = currentIndex;
										DrawItem(g, index, itemRect,
										true, false, Rectangle.Empty, null);
									}
									else
									{
										// the mouse did not hit an item
										if (itemHighlighted)
										{
											DrawItem(g, index, itemRect,
											false, false, Rectangle.Empty, null);
											itemHighlighted = false;
										}
									}
								}
							}
							else
							{
								if (hit == HitTestType.Item && currentIndex == index)
								{

									// Set no drag cursor if there have been at least
									// a 5 pixel movement
									int pixelmov = 5;
									if (bands[currentBandIndex].IconView == IconView.Small)
										pixelmov = 2;
									bool unpressed = false;
									if (Math.Abs(deltaX) >= pixelmov || Math.Abs(deltaY) >= pixelmov)
									{
										unpressed = true;
										Cursor.Current = Cursors.No;
										dragging = true;
										dragItemIndex = index;
									}

									if (itemPressed && unpressed)
									{
										DrawItem(g, index, itemRect,
										true, false, Rectangle.Empty, null);
										itemPressed = false;
										itemHighlighted = true;
									}
								}
							}
							break;
						}
						case (int)Msg.WM_LBUTTONUP:
						{

							// Highlight the item
							if (itemPressed)
							{
								DrawItem(g, index, itemRect, true, false, Rectangle.Empty, null);
								itemPressed = false;
							}

							int newIndex;
							HitTestType ht = HitTest(point, out newIndex, true);
							bool doDrop = false;
							if (dragging && (ht == HitTestType.DropLine || ht == HitTestType.DropLineLastItem))
							{
								// Delete dropline
								Cursor.Current = Cursors.Default;
								// Erase the Dragline
								DrawDropLine(g, index, false, ht);

								// Move the dragged item to the new location
								// only if the new location is not contiguous to its
								// own location
								if (dragItemIndex > droppedPosition
								&& Math.Abs(dragItemIndex - droppedPosition) > 0)
									doDrop = true;
								else if (dragItemIndex < droppedPosition
								&& Math.Abs(dragItemIndex - droppedPosition) > 1)
									doDrop = true;

								if (doDrop)
								{
									// Remove item from its old location
									OutlookBarItem dragItem = bands[currentBandIndex].Items[dragItemIndex];
									bands[currentBandIndex].Items.RemoveAt(dragItemIndex);
									// Insert item in its new location
									if (dragItemIndex < droppedPosition)
										droppedPosition--;

									bands[currentBandIndex].Items.Insert(droppedPosition, dragItem);
								}
							}

							// Repaint the bar just in case we had a dropline painted
							Invalidate();

							// Highlight item
							if (!dragging)
							{
								// do not highlight if we are dropping
								forceHightlight = true;
								forceHightlightIndex = index;
								// Fire item clicked property
								FireItemClicked(index);
							}
							else
							{
								// Fire item dropped event
								if (droppedPosition != -1 && doDrop)
									FireItemDropped(droppedPosition);
							}

							doLoop = false;
							break;
						}
						case (int)Msg.WM_KEYDOWN:
						{
							if ((int)msg.wParam == (int)VirtualKeys.VK_ESCAPE)
								doLoop = false;
							break;
						}
						default:
							WindowsAPI.DispatchMessage(ref msg);
							break;
					}
				}
			}
			Capture = false;
		}