board.java~

一个外国大学生的JAVA程序

// Board.java
package Hw2;
import java.awt.*;
import java.util.*;


/**
 Represents a Tetris board -- essentially a 2-d grid
 of booleans. Supports tetris pieces and row clearning.
 Has an "undo" feature that allows clients to add and remove pieces efficiently.
 Does not do any drawing or have any idea of pixels. Intead,
 just represents the abtsract 2-d board.
  See Tetris-Architecture.html for an overview.
  
 This is the starter file version -- a few simple things are filled in already
  
 @author	Nick Parlante
 @version	1.0, Mar 1, 2001
*/
public final class Board  {
	private int width;
	private int height;
        
        private int[] widths;
        private int[] heights;
	private boolean[][] grid;
        
        private int[] xwidths;
        private int[] xheights;
        private boolean[][] xgrid;
        
	private int scol; // start col for backup
        private int ecol; // end col for backup
        
        private boolean fast_undo = true;
        
        private boolean committed;
		
	private boolean DEBUG = false;
	
	
	/**
	 Creates an empty board of the given width and height
	 measured in blocks.
	*/
	public Board(int aWidth, int aHeight) {
		width = aWidth;
		height = aHeight;

		grid = new boolean[width][height];
                widths = new int[height];
                heights = new int[width];
                
                xgrid = new boolean[width][height];
                xwidths = new int[height];
                xheights = new int[width];
                
                committed = true;
	}
	
	
	/**
	 Returns the width of the board in blocks.
	*/
	public int getWidth() {
		return width;
	}
	
	
	/**
	 Returns the height of the board in blocks.
	*/
	public int getHeight() {
		return height;
	}
	
	
	/**
	 Returns the max column height present in the board.
	 For an empty board this is 0.
	*/
	public int getMaxHeight() {
            int max = 0;
            for(int i = 0; i < width; i++) {
                if (heights[i] > max) max = heights[i];
            }
            return max;

	}
	
	
	/**
	 Checks the board for internal consistency -- used
	 for debugging.
	*/
	public void sanityCheck() {
		if (DEBUG) {
			// consistency check the board state
                    // check widths[]
                    
                    int temp = 0;
                    for(int i = 0; i < height; i++) {
                        for(int j = 0; j < width; j++) {
                            if(grid[j][i]) temp++;
                        }
                        if(temp != widths[i]) throw new RuntimeException("Widths[] array is CrAzY!");
                        temp = 0;
                    }
                    
                    
                    // check heights[]
                    temp = 0;
                    int max = 0;
                    for(int i = 0; i < width; i++) {
                        for(int j = height-1; j >= 0; j--) {
                            if(grid[i][j]) {
                                temp = j+1;
                                if(j+1 > max) max = j+1;
                                break;
                            }
                        }
                        if(temp != heights[i]) {
                            throw new RuntimeException("Heights[] array is CrAzY!");
                        }
                        temp = 0;
                    }
                    
                    // check max height
                    if(getMaxHeight() != max) {
                        throw new RuntimeException("HieghtMax is CRAzY!!!!");
                    }
              }
	}
	
	/**
	 Given a piece and an x, returns the y
	 value where the piece would come to rest
	 if it were dropped straight down at that x.
	 
	 <p>
	 Implementation: use the skirt and the col heights
	 to compute this fast -- O(skirt length).
	*/
	public int dropHeight(Piece piece, int x) {
            int high = 10000;
            int result = 0;
            int temp;
            int i;
            int[] skirt = piece.getSkirt();
            for(i = x; i < x + piece.getWidth(); i++) {
                temp = skirt[i-x]-heights[i];
                if(temp < high) {
                    high = temp;
                    result = i;
                }
            }
            return heights[result]-skirt[result-x];
	}
	
	
	/**
	 Returns the height of the given column --
	 i.e. the y value of the highest block + 1.
	 The height is 0 if the column contains no blocks.
	*/
	public int getColumnHeight(int x) {
            return heights[x];
	}
	
	
	/**
	 Returns the number of filled blocks in
	 the given row.
	*/
	public int getRowWidth(int y) {
            return widths[y];
	}
	
	
	/**
	 Returns true if the given block is filled in the board.
	 Blocks outside of the valid width/height area
	 always return true.
	*/
	public final boolean getGrid(int x, int y) {
            if(x<0 || x>width) return true;
            if(y<0 || y>height) return true;
            return grid[x][y];
	}
	
	
	public static final int PLACE_OK = 0;
	public static final int PLACE_ROW_FILLED = 1;
	public static final int PLACE_OUT_BOUNDS = 2;
	public static final int PLACE_BAD = 3;
	
	/**
	 Attempts to add the body of a piece to the board.
	 Copies the piece blocks into the board grid.
	 Returns PLACE_OK for a regular placement, or PLACE_ROW_FILLED
	 for a regular placement that causes at least one row to be filled.
	 
	 <p>Error cases:
	 If part of the piece would fall out of bounds, the placement
	 does not change the board at all, and PLACE_OUT_BOUNDS is returned.
	 If the placement is "bad" --interfering with existing blocks in the grid --
	 then the placement is halted partially complete and PLACE_BAD is returned.
	 An undo() will remove the bad placement.
	*/
	public int place(Piece piece, int x, int y) {
            Point[] body = piece.getBody();
            int putx;
            int puty;
            boolean row_filled = false;
            
            if(!committed) throw new RuntimeException("Trying to place on uncommited board!!!");
            committed = false;
            backup();
            
            // might as well do all the error checking at once, since we must leave the board unchanged if we've got
            // an out of bounds error - this has the added bonus of not altering the board on a bad place
            for(int i = 0; i < body.length; i++) {
                putx = x+body[i].x;
                puty = y+body[i].y;
                if(putx<0 || putx>=width) return PLACE_OUT_BOUNDS;
                if(puty<0 || puty>=height) return PLACE_OUT_BOUNDS;
                if(grid[putx][puty]) return PLACE_BAD;
            }
            for(int i = 0; i < body.length; i++) {
                putx = x+body[i].x;
                puty = y+body[i].y;
                
                grid[putx][puty] = true;
                widths[puty]++;
                if(puty+1 > heights[putx]) heights[putx] = puty+1;
                
                if(widths[puty] >= width) row_filled = true;
                
            }
            
            sanityCheck();
            
            if(row_filled) return PLACE_ROW_FILLED;
            return PLACE_OK;
	}

	/**
	 Deletes rows that are filled all the way across, moving
	 things above down. Returns true if any row clearing happened.
	 
	 <p>Implementation: This is complicated.
	 Ideally, you want to copy each row down
	 to its correct location in one pass.
	 Note that more than one row may be filled.
	*/
	public boolean clearRows() {
            boolean cleared = false;
            
            if(committed) backup(); // not calling immediately after place
            committed = false;
            
            for(int i = 0; i < height; i++) {
                if(widths[i] >= width) {
                    cleared = true;
                    
                    for(int j = 0; j < width; j++) {
                        System.arraycopy(grid[j],i+1,grid[j],i,height-1-i);
                        grid[j][height-1] = false;
                    }
                    System.arraycopy(widths,i+1,widths,i, height-1-i);
                    widths[height-1] = 0;
                    i--;
                }
            }

            if(cleared) recalcHeights();
            sanityCheck();
            return cleared;
            
	}
            
        private void recalcHeights() {
            int j;
            boolean sent = false;
            for(int i = 0; i < width; i++) {
                sent = false;
                for(j = height-1; j >=0 ; j--) {
                    if(grid[i][j] && !sent) {
                        heights[i] = j+1;
                        sent = true;
                    }
                }
                if(!sent) heights[i] = 0;

                
            }
            
        }



	/**
	 If a place() happens, optionally followed by a clearRows(),
	 a subsequent undo() reverts the board to its state before
	 the place(). If the conditions for undo() are not met, such as
	 calling undo() twice in a row, then the second undo() does nothing.
	 See the overview docs.
	*/
	public void undo() {
            if(!committed) {
                int[] temp;
                boolean[][] temp2;
                
                temp = widths;
                widths = xwidths;
                xwidths = temp;
                
                temp = heights;
                heights = xheights;
                xheights = temp;
                
                temp2 = grid;
                grid = xgrid;
                xgrid = temp2;
                
                /*
                for(int i = 0; i < width; i++) {
                    System.arraycopy(xgrid[i],0,grid[i],0,height);
                }
                System.arraycopy(xwidths,0,widths,0,height);
                System.arraycopy(xheights,0,heights,0,width); 
                 */
                committed = true;
            }
            sanityCheck();
        }
        
        
	
        private void backup() {
            for(int i = 0; i < width; i++) {
               System.arraycopy(grid[i],0,xgrid[i],0,height);
            }
            System.arraycopy(widths,0,xwidths,0,height);
            System.arraycopy(heights,0,xheights,0,width);
        }
	
	/**
	 Puts the board in the committed state.
	 See the overview docs.
	*/
	public void commit() {
            if(!committed) {
     /*           for(int i = 0; i < width; i++) {
                    System.arraycopy(grid[i],0,xgrid[i],0,height);
                }
                System.arraycopy(widths,0,xwidths,0,height);
                System.arraycopy(heights,0,xheights,0,width); */
                committed = true;
            }
	}
}