background.cs

Pocket 1945 is a classic shooter inspired by the classic 1942 game. The game is written in C# target

using System;
using System.Drawing;
using System.Drawing.Imaging;

namespace Pocket1945
{
	/// <summary>
	/// This class draws the background of the game.
	/// </summary>
	public class Background : IDrawable
	{		
		/// <summary>
		/// The current Y position of the map. 0 is at the end of the map.
		/// </summary>
		public int Y;

		/// <summary>
		/// The total height of the map. Used to messure progress.
		/// </summary>
		public int Height;

		/// <summary>
		/// The speed the map is scrolling at.
		/// </summary>
		public double Speed;		
		
		private double y;		
		private Rectangle focusRectangle;
		private Bitmap background;
		private ImageAttributes imgAttribs;
		
		/// <summary>
		/// Instanciates a new background.
		/// </summary>
		/// <param name="map">The map to draw for the level.</param>
		/// <param name="backgroundElements">The backgroundelements to draw for the level.</param>
		public Background(string[] map, BackgroundElement[] backgroundElements)
		{				
			int spriteWidth = 32;
			y = (map.Length * spriteWidth) - GameForm.GameArea.Height;
			focusRectangle = new Rectangle(0, map.Length * spriteWidth, GameForm.GameArea.Width, GameForm.GameArea.Height);			
			Height = focusRectangle.Y - GameForm.GameArea.Height;
			background = new Bitmap(GameForm.GameArea.Width, map.Length * spriteWidth);
			Graphics g = Graphics.FromImage(background);

			imgAttribs = new ImageAttributes();
			imgAttribs.SetColorKey(Color.FromArgb(0, 66, 173), Color.FromArgb(0, 66, 173));

			//Loop trough all map strings.
			for(int i = 0; i < map.Length; ++i)
			{
				//Create a char array of all map elements.
				char[] mapElements = map[i].ToCharArray();

				//Loop trough all chars in the map string.
				for(int j = 0; j < mapElements.Length; ++j)
				{
					//Drawnig the map element to the map bitmap.
					int index = SpriteList.Instance.GetTileIndex(mapElements[j]);
					int n = SpriteList.Instance.Tiles.Length;
					g.DrawImage(SpriteList.Instance.Tiles[index], j * spriteWidth, i * spriteWidth);
				}
			}

			//Loop trough all background elements.
			for(int i = 0; i < backgroundElements.Length; ++i)
			{
				BackgroundElement e = backgroundElements[i];				

				//Draw the map element to the map bitmap.
				if(e.Width > 32)
					g.DrawImage(SpriteList.Instance.BigBackgroundElements[e.SpriteIndex], new Rectangle(e.X, e.Y, e.Width, e.Height), 0, 0, e.Width, e.Height, GraphicsUnit.Pixel, imgAttribs);				
			}

			//Dispose the graphics element used to draw the background.
			g.Dispose();
		}

		/// <summary>
		/// Implemention of IDrawable interface making the background able to draw itself.
		/// </summary>
		/// <param name="g">The graphics object used to draw the background.</param>
		public void Draw(Graphics g)
		{	
			//Scrolling the background and increasing the y co-ordinate.
			if(y > 0)
			{
				y -= Speed;
				focusRectangle.Y = (int)y;
				Y = focusRectangle.Y;
			}

			//Drawing the active part of the map to the back buffer bitmap.
			g.DrawImage(background, GameForm.GameArea, focusRectangle, GraphicsUnit.Pixel);
		}	
	}
}