context: #region Copyright & License Information
  /*
   * Copyright 2007-2015 The OpenRA Developers (see AUTHORS)
   * This file is part of OpenRA, which is free software. It is made
   * available to you under the terms of the GNU General Public License
   * as published by the Free Software Foundation. For more information,
   * see COPYING.
   */
  #endregion
  
  using System.Collections.Generic;
  using System.Drawing;
  using System.Linq;
  using OpenRA.Effects;
  using OpenRA.Graphics;
  using OpenRA.Orders;
  using OpenRA.Primitives;
  using OpenRA.Traits;
  
  namespace OpenRA.Widgets
  {
  	public class WorldInteractionControllerWidget : Widget
  	{
  		protected readonly World World;
  		readonly WorldRenderer worldRenderer;
  		int2? dragStart, dragEnd;
  		int2 lastMousePosition;
  
  		[ObjectCreator.UseCtor]
  		public WorldInteractionControllerWidget(World world, WorldRenderer worldRenderer)
  		{
  			this.World = world;
  			this.worldRenderer = worldRenderer;
  		}
  
  		public override void Draw()
  		{
  			if (!IsDragging)
  			{
  				// Render actors under the mouse pointer
  				foreach (var u in SelectActorsInBoxWithDeadzone(World, lastMousePosition, lastMousePosition))
  					worldRenderer.DrawRollover(u);
  
  				return;
  			}
  
  			// Render actors in the dragbox
  			var selbox = SelectionBox;
  			Game.Renderer.WorldLineRenderer.DrawRect(selbox.Value.First.ToFloat2(), selbox.Value.Second.ToFloat2(), Color.White);
  			foreach (var u in SelectActorsInBoxWithDeadzone(World, selbox.Value.First, selbox.Value.Second))
  				worldRenderer.DrawRollover(u);
  		}
  
  		public override bool HandleMouseInput(MouseInput mi)
  		{
  			var xy = worldRenderer.Viewport.ViewToWorldPx(mi.Location);
  
  			var useClassicMouseStyle = Game.Settings.Game.UseClassicMouseStyle;
  
  			var hasBox = SelectionBox != null;
  			var multiClick = mi.MultiTapCount >= 2;
  
  			if (mi.Button == MouseButton.Left && mi.Event == MouseInputEvent.Down)
  			{
  				if (!TakeMouseFocus(mi))
  					return false;
  
  				dragStart = xy;
  
  				// Place buildings, use support powers, and other non-unit things
  				if (!(World.OrderGenerator is UnitOrderGenerator))
  				{
  					ApplyOrders(World, mi);
  					dragStart = dragEnd = null;
  					YieldMouseFocus(mi);
  					lastMousePosition = xy;
  					return true;
  				}
  			}
  
  			if (mi.Button == MouseButton.Left && mi.Event == MouseInputEvent.Move && dragStart.HasValue)
  				dragEnd = xy;
  
  			if (mi.Button == MouseButton.Left && mi.Event == MouseInputEvent.Up)
  			{
  				if (World.OrderGenerator is UnitOrderGenerator)
  				{
  					if (useClassicMouseStyle && HasMouseFocus)
  					{
  						if (!hasBox && World.Selection.Actors.Any() && !multiClick)
  						{
  							if (!(World.ScreenMap.ActorsAt(xy).Where(x => x.Info.HasTraitInfo<SelectableInfo>() &&
  								(x.Owner.IsAlliedWith(World.RenderPlayer) || !World.FogObscures(x))).Any() && !mi.Modifiers.HasModifier(Modifiers.Ctrl) &&
  								!mi.Modifiers.HasModifier(Modifiers.Alt) && UnitOrderGenerator.InputOverridesSelection(World, xy, mi)))
  							{
  								// Order units instead of selecting
  								ApplyOrders(World, mi);
  								dragStart = dragEnd = null;
  								YieldMouseFocus(mi);
  								lastMousePosition = xy;
  								return true;
  							}
  						}
  					}
  
  					if (multiClick)
  					{
  						var unit = World.ScreenMap.ActorsAt(xy)
  							.WithHighestSelectionPriority();
  
  						if (unit != null && unit.Owner == (World.RenderPlayer ?? World.LocalPlayer))
  						{
  							var s = unit.TraitOrDefault<Selectable>();
  							if (s != null)
  							{
  								// Select actors on the screen that have the same selection class as the actor under the mouse cursor
  								var newSelection = SelectActorsOnScreen(World, worldRenderer, new HashSet<string> { s.Class }, unit.Owner);
  
  								World.Selection.Combine(World, newSelection, true, false);
  							}
  						}
  					}
  					else if (dragStart.HasValue)
  					{
  						// Select actors in the dragbox
  						var newSelection = SelectActorsInBoxWithDeadzone(World, dragStart.Value, xy);
  						World.Selection.Combine(World, newSelection, mi.Modifiers.HasModifier(Modifiers.Shift), dragStart == xy);
  					}
  				}
  
  				dragStart = dragEnd = null;
  				YieldMouseFocus(mi);
  			}
  
  			if (mi.Button == MouseButton.Right && mi.Event == MouseInputEvent.Down)
  			{
  				// Don't do anything while selecting
  				if (!hasBox)
  				{
  					if (useClassicMouseStyle)
  						World.Selection.Clear();
  
  					ApplyOrders(World, mi);
  				}
  			}
  
  			lastMousePosition = xy;
  
  			return true;
  		}
  
  		bool IsDragging
  		{
  			get
  			{
  				return dragStart.HasValue && dragEnd.HasValue && (dragStart.Value - dragEnd.Value).Length > Game.Settings.Game.SelectionDeadzone;
  			}
  		}
  
  		public Pair<int2, int2>? SelectionBox
  		{
  			get
  			{
  				if (!IsDragging) return null;
  				return Pair.New(dragStart.Value, dragEnd.Value);
  			}
  		}
  
  		void ApplyOrders(World world, MouseInput mi)
  		{
  			if (world.OrderGenerator == null)
  				return;
  
  			var cell = worldRenderer.Viewport.ViewToWorld(mi.Location);
  			var orders = world.OrderGenerator.Order(world, cell, mi).ToArray();
  			world.PlayVoiceForOrders(orders);
  
  			var flashed = false;
  			foreach (var order in orders)
  			{
  				var o = order;
  				if (o == null)
  					continue;
  
  				if (!flashed && !o.SuppressVisualFeedback)
  				{
  					if (o.TargetActor != null)
  					{
  						world.AddFrameEndTask(w => w.Add(new FlashTarget(o.TargetActor)));
  						flashed = true;
  					}
  					else if (o.TargetLocation != CPos.Zero)
  					{
  						var pos = world.Map.CenterOfCell(cell);
  						world.AddFrameEndTask(w => w.Add(new SpriteEffect(pos, world, "moveflsh", "moveflash")));
  						flashed = true;
  					}
  				}
  
  				world.IssueOrder(o);
  			}
  		}
  
  		public override string GetCursor(int2 screenPos)
  		{
  			return Sync.CheckSyncUnchanged(World, () =>
  			{
  				// Always show an arrow while selecting
  				if (SelectionBox != null)
  					return null;
  
  				var cell = worldRenderer.Viewport.ViewToWorld(screenPos);
  
  				var mi = new MouseInput
  				{
  					Location = screenPos,
  					Button = Game.Settings.Game.MouseButtonPreference.Action,
  					Modifiers = Game.GetModifierKeys()
  				};
  
  				return World.OrderGenerator.GetCursor(World, cell, mi);
  			});
  		}
  
  		public override bool HandleKeyPress(KeyInput e)
  		{
  			var player = World.RenderPlayer ?? World.LocalPlayer;
  
  			if (e.Event == KeyInputEvent.Down)
  			{
  				var key = Hotkey.FromKeyInput(e);
  
  				if (key == Game.Settings.Keys.PauseKey && World.LocalPlayer != null) // Disable pausing for spectators
  					World.SetPauseState(!World.Paused);
  				else if (key == Game.Settings.Keys.SelectAllUnitsKey && !World.IsGameOver)
  				{
  					// Select actors on the screen which belong to the current player
  					var ownUnitsOnScreen = SelectActorsOnScreen(World, worldRenderer, null, player).SubsetWithHighestSelectionPriority();
  
gt: 					World.Selection.Combine(World, ownUnitsOnScreen, false, false);