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;
  using System.Collections;
  using System.Collections.Generic;
  using System.Drawing;
  using System.Linq;
  
  namespace OpenRA.Graphics
  {
  	[Flags]
  	public enum ScrollDirection { None = 0, Up = 1, Left = 2, Down = 4, Right = 8 }
  
  	public static class ViewportExts
  	{
  		public static bool Includes(this ScrollDirection d, ScrollDirection s)
  		{
  			return (d & s) == s;
  		}
  
  		public static ScrollDirection Set(this ScrollDirection d, ScrollDirection s, bool val)
  		{
  			return (d.Includes(s) != val) ? d ^ s : d;
  		}
  	}
  
  	public class Viewport
  	{
  		readonly WorldRenderer worldRenderer;
  
  		// Map bounds (world-px)
  		readonly Rectangle mapBounds;
  		readonly Size tileSize;
  
  		// Viewport geometry (world-px)
  		public int2 CenterLocation { get; private set; }
  
  		public WPos CenterPosition { get { return worldRenderer.ProjectedPosition(CenterLocation); } }
  
  		public int2 TopLeft { get { return CenterLocation - viewportSize / 2; } }
  		public int2 BottomRight { get { return CenterLocation + viewportSize / 2; } }
  		int2 viewportSize;
  		CellRegion cells;
  		bool cellsDirty = true;
  
  		CellRegion allCells;
  		bool allCellsDirty = true;
  
  		float zoom = 1f;
  		public float Zoom
  		{
  			get
  			{
  				return zoom;
  			}
  
  			set
  			{
  				zoom = value;
  				viewportSize = (1f / zoom * new float2(Game.Renderer.Resolution)).ToInt2();
  				cellsDirty = true;
  				allCellsDirty = true;
  			}
  		}
  
  		public static int TicksSinceLastMove = 0;
  		public static int2 LastMousePos;
  
  		public ScrollDirection GetBlockedDirections()
  		{
  			var ret = ScrollDirection.None;
  			if (CenterLocation.Y <= mapBounds.Top)
  				ret |= ScrollDirection.Up;
  			if (CenterLocation.X <= mapBounds.Left)
  				ret |= ScrollDirection.Left;
  			if (CenterLocation.Y >= mapBounds.Bottom)
  				ret |= ScrollDirection.Down;
  			if (CenterLocation.X >= mapBounds.Right)
  				ret |= ScrollDirection.Right;
  
  			return ret;
  		}
  
  		public Viewport(WorldRenderer wr, Map map)
  		{
  			worldRenderer = wr;
  
  			var cells = wr.World.Type == WorldType.Editor ?
  				map.AllCells : map.CellsInsideBounds;
  
  			// Calculate map bounds in world-px
  			var tl = wr.ScreenPxPosition(map.CenterOfCell(cells.TopLeft) - new WVec(512, 512, 0));
  			var br = wr.ScreenPxPosition(map.CenterOfCell(cells.BottomRight) + new WVec(511, 511, 0));
  			mapBounds = Rectangle.FromLTRB(tl.X, tl.Y, br.X, br.Y);
  
  			CenterLocation = (tl + br) / 2;
  			Zoom = Game.Settings.Graphics.PixelDouble ? 2 : 1;
  			tileSize = Game.ModData.Manifest.TileSize;
  		}
  
  		public CPos ViewToWorld(int2 view)
  		{
  			var world = worldRenderer.Viewport.ViewToWorldPx(view);
  			var map = worldRenderer.World.Map;
  			var ts = Game.ModData.Manifest.TileSize;
  			var candidates = CandidateMouseoverCells(world);
  			var tileSet = worldRenderer.World.TileSet;
  
  			foreach (var uv in candidates)
  			{
  				// Coarse filter to nearby cells
  				var p = map.CenterOfCell(uv.ToCPos(map.TileShape));
  				var s = worldRenderer.ScreenPxPosition(p);
  				if (Math.Abs(s.X - world.X) <= ts.Width && Math.Abs(s.Y - world.Y) <= ts.Height)
  				{
  					var ramp = 0;
  					if (map.Contains(uv))
  					{
  						var tile = map.MapTiles.Value[uv];
  						var ti = tileSet.GetTileInfo(tile);
  						if (ti != null)
  							ramp = ti.RampType;
  					}
  
  					var corners = map.CellCorners[ramp];
  					var pos = map.CenterOfCell(uv.ToCPos(map));
  					var screen = corners.Select(c => worldRenderer.ScreenPxPosition(pos + c)).ToArray();
  
  					if (screen.PolygonContains(world))
  						return uv.ToCPos(map);
  				}
  			}
  
  			// Mouse is not directly over a cell (perhaps on a cliff)
  			// Try and find the closest cell
  			if (candidates.Any())
  			{
  				return candidates.OrderBy(uv =>
  				{
  					var p = map.CenterOfCell(uv.ToCPos(map.TileShape));
  					var s = worldRenderer.ScreenPxPosition(p);
  					var dx = Math.Abs(s.X - world.X);
  					var dy = Math.Abs(s.Y - world.Y);
  
  					return dx * dx + dy * dy;
  				}).First().ToCPos(map);
  			}
  
  			// Something is very wrong, but lets return something that isn't completely bogus and hope the caller can recover
  			return worldRenderer.World.Map.CellContaining(worldRenderer.ProjectedPosition(ViewToWorldPx(view)));
  		}
  
  		/// <summary> Returns an unfiltered list of all cells that could potentially contain the mouse cursor</summary>
  		IEnumerable<MPos> CandidateMouseoverCells(int2 world)
  		{
  			var map = worldRenderer.World.Map;
  			var minPos = worldRenderer.ProjectedPosition(world);
  
  			// Find all the cells that could potentially have been clicked
  			var a = map.CellContaining(minPos - new WVec(1024, 0, 0)).ToMPos(map.TileShape);
  			var b = map.CellContaining(minPos + new WVec(512, 512 * map.MaximumTerrainHeight, 0)).ToMPos(map.TileShape);
  
  			for (var v = b.V; v >= a.V; v--)
  				for (var u = b.U; u >= a.U; u--)
  					yield return new MPos(u, v);
  		}
  
  		public int2 ViewToWorldPx(int2 view) { return (1f / Zoom * view.ToFloat2()).ToInt2() + TopLeft; }
  		public int2 WorldToViewPx(int2 world) { return (Zoom * (world - TopLeft).ToFloat2()).ToInt2(); }
  
  		public void Center(IEnumerable<Actor> actors)
  		{
  			if (!actors.Any())
  				return;
  
  			Center(actors.Select(a => a.CenterPosition).Average());
  		}
  
  		public void Center(WPos pos)
  		{
  			CenterLocation = worldRenderer.ScreenPxPosition(pos).Clamp(mapBounds);
  			cellsDirty = true;
  			allCellsDirty = true;
  		}
  
  		public void Scroll(float2 delta, bool ignoreBorders)
  		{
  			// Convert scroll delta from world-px to viewport-px
  			CenterLocation += (1f / Zoom * delta).ToInt2();
  			cellsDirty = true;
  			allCellsDirty = true;
  
  			if (!ignoreBorders)
  				CenterLocation = CenterLocation.Clamp(mapBounds);
  		}
  
  		// Rectangle (in viewport coords) that contains things to be drawn
  		static readonly Rectangle ScreenClip = Rectangle.FromLTRB(0, 0, Game.Renderer.Resolution.Width, Game.Renderer.Resolution.Height);
  		public Rectangle GetScissorBounds(bool insideBounds)
  		{
  			// Visible rectangle in world coordinates (expanded to the corners of the cells)
  			var bounds = insideBounds ? VisibleCellsInsideBounds : AllVisibleCells;
  			var map = worldRenderer.World.Map;
  			var ctl = map.CenterOfCell(bounds.TopLeft) - new WVec(512, 512, 0);
  			var cbr = map.CenterOfCell(bounds.BottomRight) + new WVec(512, 512, 0);
  
  			// Convert to screen coordinates
  			var tl = WorldToViewPx(worldRenderer.ScreenPxPosition(ctl - new WVec(0, 0, ctl.Z))).Clamp(ScreenClip);
  			var br = WorldToViewPx(worldRenderer.ScreenPxPosition(cbr - new WVec(0, 0, cbr.Z))).Clamp(ScreenClip);
  
  			// Add an extra one cell fudge in each direction for safety
  			return Rectangle.FromLTRB(tl.X - tileSize.Width, tl.Y - tileSize.Height,
  				br.X + tileSize.Width, br.Y + tileSize.Height);
  		}
  
  		CellRegion CalculateVisibleCells(bool insideBounds)
  		{
  			var map = worldRenderer.World.Map;
  
  			// Calculate the viewport corners in "projected wpos" (at ground level), and
  			// this to an equivalent projected cell for the two corners
  			var tl = map.CellContaining(worldRenderer.ProjectedPosition(TopLeft)).ToMPos(map);
  			var br = map.CellContaining(worldRenderer.ProjectedPosition(BottomRight)).ToMPos(map);
  
  			// Diamond tile shapes don't have straight edges, and so we need
  			// an additional cell margin to include the cells that are half
  			// visible on each edge.
  			if (map.TileShape == TileShape.Diamond)
  			{
  				tl = new MPos(tl.U - 1, tl.V - 1);
  				br = new MPos(br.U + 1, br.V + 1);
  			}
  
  			// Clamp to the visible map bounds, if requested
  			if (insideBounds)
  			{
  
gt: 				tl = map.Clamp(tl);