Android Open Source - android-snake-example Snake View

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The source code is released under:

Apache License

Java Source Code

/*
 * Copyright (C) 2007 The Android Open Source Project
 */*from w  w  w .  j a v a2  s .  c o  m*/
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.snake;

import java.util.ArrayList;
import java.util.Random;

import org.code.kata.snake.Coordinates;
import org.code.kata.snake.Game;
import org.code.kata.snake.GameFactory;
import org.code.kata.snake.Snake;
import org.code.kata.snake.SnakeHitYardWallException;
import org.code.kata.snake.SnakeRenderer;
import org.code.kata.snake.Yard;

import android.content.Context;
import android.content.res.Resources;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.widget.TextView;

/**
 * SnakeView: implementation of a simple game of Snake
 * 
 * 
 */
public class SnakeView extends TileView {

    private static final String TAG = "SnakeView";

    /**
     * Current mode of application: READY to run, RUNNING, or you have already
     * lost. static final ints are used instead of an enum for performance
     * reasons.
     */
    private int mMode = READY;
    public static final int PAUSE = 0;
    public static final int READY = 1;
    public static final int RUNNING = 2;
    public static final int LOSE = 3;

    /**
     * Current direction the snake is headed.
     */
    /* TODO
    private int mDirection = NORTH;
    private int mNextDirection = NORTH;
  */
    private static final String NORTH = "U";
    private static final String SOUTH = "D";
    private static final String EAST = "R";
    private static final String WEST = "L";
    Game game;
    
    /**
     * Labels for the drawables that will be loaded into the TileView class
     */
    private static final int RED_STAR = 1;
    private static final int YELLOW_STAR = 2;
    private static final int GREEN_STAR = 3;

    /**
     * mScore: used to track the number of apples captured mMoveDelay: number of
     * milliseconds between snake movements. This will decrease as apples are
     * captured.
     */
    private long mScore = 0;
    // TODO private long mMoveDelay = 600;
    /**
     * mLastMove: tracks the absolute time when the snake last moved, and is used
     * to determine if a move should be made based on mMoveDelay.
     */
    // TODO private long mLastMove;
    
    /**
     * mStatusText: text shows to the user in some run states
     */
    private TextView mStatusText;

    /**
     * mSnakeTrail: a list of Coordinates that make up the snake's body
     * mAppleList: the secret location of the juicy apples the snake craves.
     */
    // TODO private ArrayList<Coordinate> mSnakeTrail = new ArrayList<Coordinate>();
    private ArrayList<Coordinate> mAppleList = new ArrayList<Coordinate>();

    /**
     * Everyone needs a little randomness in their life
     */
    private static final Random RNG = new Random();

    /**
     * Create a simple handler that we can use to cause animation to happen.  We
     * set ourselves as a target and we can use the sleep()
     * function to cause an update/invalidate to occur at a later date.
     */
    private RefreshHandler mRedrawHandler = new RefreshHandler();

    class RefreshHandler extends Handler {

        @Override
        public void handleMessage(Message msg) {
            SnakeView.this.update();
            SnakeView.this.invalidate();
        }

        public void sleep(long delayMillis) {
          this.removeMessages(0);
            sendMessageDelayed(obtainMessage(0), delayMillis);
        }
    };


    /**
     * Constructs a SnakeView based on inflation from XML
     * 
     * @param context
     * @param attrs
     */
    public SnakeView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initSnakeView();
   }

    public SnakeView(Context context, AttributeSet attrs, int defStyle) {
      super(context, attrs, defStyle);
      initSnakeView();
    }

    private void initSnakeView() {
        setFocusable(true);

        Resources r = this.getContext().getResources();
        
        resetTiles(4);
        loadTile(RED_STAR, r.getDrawable(R.drawable.redstar));
        loadTile(YELLOW_STAR, r.getDrawable(R.drawable.yellowstar));
        loadTile(GREEN_STAR, r.getDrawable(R.drawable.greenstar));
      
    }
    

    private void initNewGame() {
        // TODO mSnakeTrail.clear();
        mAppleList.clear();

        // For now we're just going to load up a short default eastbound snake
        // that's just turned north

        
        /* TODO
        mSnakeTrail.add(new Coordinate(7, 7));
        mSnakeTrail.add(new Coordinate(6, 7));
        mSnakeTrail.add(new Coordinate(5, 7));
        mSnakeTrail.add(new Coordinate(4, 7));
        mSnakeTrail.add(new Coordinate(3, 7));
        mSnakeTrail.add(new Coordinate(2, 7));
        mNextDirection = NORTH;
        */
        this.game = GameFactory.createGameWithYardDimensions(TileView.mXTileCount, TileView.mYTileCount);
        game.init();
        
        // Two apples to start with
        addRandomApple();
        addRandomApple();

        // TODO mMoveDelay = 600;
        mScore = 0;
    }


    /**
     * Given a ArrayList of coordinates, we need to flatten them into an array of
     * ints before we can stuff them into a map for flattening and storage.
     * 
     * @param cvec : a ArrayList of Coordinate objects
     * @return : a simple array containing the x/y values of the coordinates
     * as [x1,y1,x2,y2,x3,y3...]
     */
    private int[] coordArrayListToArray(ArrayList<Coordinate> cvec) {
        int count = cvec.size();
        int[] rawArray = new int[count * 2];
        for (int index = 0; index < count; index++) {
            Coordinate c = cvec.get(index);
            rawArray[2 * index] = c.x;
            rawArray[2 * index + 1] = c.y;
        }
        return rawArray;
    }

    /**
     * Save game state so that the user does not lose anything
     * if the game process is killed while we are in the 
     * background.
     * 
     * @return a Bundle with this view's state
     */
    public Bundle saveState() {
        Bundle map = new Bundle();

        map.putIntArray("mAppleList", coordArrayListToArray(mAppleList));
        // TODO map.putInt("mDirection", Integer.valueOf(mDirection));
        // TODO map.putInt("mNextDirection", Integer.valueOf(mNextDirection));
        // TODO map.putLong("mMoveDelay", Long.valueOf(mMoveDelay));
        map.putLong("mScore", Long.valueOf(mScore));
        // TODO map.putIntArray("mSnakeTrail", coordArrayListToArray(mSnakeTrail));

        return map;
    }

    /**
     * Given a flattened array of ordinate pairs, we reconstitute them into a
     * ArrayList of Coordinate objects
     * 
     * @param rawArray : [x1,y1,x2,y2,...]
     * @return a ArrayList of Coordinates
     */
    private ArrayList<Coordinate> coordArrayToArrayList(int[] rawArray) {
        ArrayList<Coordinate> coordArrayList = new ArrayList<Coordinate>();

        int coordCount = rawArray.length;
        for (int index = 0; index < coordCount; index += 2) {
            Coordinate c = new Coordinate(rawArray[index], rawArray[index + 1]);
            coordArrayList.add(c);
        }
        return coordArrayList;
    }

    /**
     * Restore game state if our process is being relaunched
     * 
     * @param icicle a Bundle containing the game state
     */
    public void restoreState(Bundle icicle) {
        setMode(PAUSE);

        mAppleList = coordArrayToArrayList(icicle.getIntArray("mAppleList"));
        // TODO mDirection = icicle.getInt("mDirection");
        // TODO mNextDirection = icicle.getInt("mNextDirection");
        // TODO mMoveDelay = icicle.getLong("mMoveDelay");
        mScore = icicle.getLong("mScore");
        // TODO mSnakeTrail = coordArrayToArrayList(icicle.getIntArray("mSnakeTrail"));
    }
    
    

    /*
     * The original example required a D-Pad present on the device.
     * Since I have a Samsung Galaxy Mini (GT-S5570) I copied the
     * behaviour from the onKeyDown() to this onTouchEvent() method.
     * Therefore, you can control the snake by touching the phone screen. 
     */
    @Override
  public boolean onTouchEvent(MotionEvent event) {
        if (mMode == READY | mMode == LOSE) {
            /*
             * At the beginning of the game, or the end of a previous one,
             * we should start a new game.
             */
            initNewGame();
            setMode(RUNNING);
            update();
        }

        if (mMode == PAUSE) {
            /*
             * If the game is merely paused, we should just continue where
             * we left off.
             */
            setMode(RUNNING);
            update();
        }
        
        // On every touch of the phone screen the snake turns clockwise
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
          Snake snake = this.game.getYard().getSnake();
      String mDirection = snake.getCurrentDirection();
      
          if (SOUTH.equals(mDirection)) {
              snake.headLeft();
          }
          
          if (WEST.equals(mDirection)) {
            snake.headUp();
          }
  
          if (NORTH.equals(mDirection)) {
            snake.headRight();
          }
          
          if (EAST.equals(mDirection)) {
            snake.headDown();
          }
        }

        return true;
  }


  /**
     * Sets the TextView that will be used to give information (such as "Game
     * Over" to the user.
     * 
     * @param newView
     */
    public void setTextView(TextView newView) {
        mStatusText = newView;
    }

    /**
     * Updates the current mode of the application (RUNNING or PAUSED or the like)
     * as well as sets the visibility of textview for notification
     * 
     * @param newMode
     */
    public void setMode(int newMode) {
        int oldMode = mMode;
        mMode = newMode;

        if (newMode == RUNNING & oldMode != RUNNING) {
            mStatusText.setVisibility(View.INVISIBLE);
            update();
            return;
        }

        Resources res = getContext().getResources();
        CharSequence str = "";
        if (newMode == PAUSE) {
            str = res.getText(R.string.mode_pause);
        }
        if (newMode == READY) {
            str = res.getText(R.string.mode_ready);
        }
        if (newMode == LOSE) {
            str = res.getString(R.string.mode_lose_prefix) + mScore
                  + res.getString(R.string.mode_lose_suffix);
        }

        mStatusText.setText(str);
        mStatusText.setVisibility(View.VISIBLE);
    }

    /**
     * Selects a random location within the garden that is not currently covered
     * by the snake. Currently _could_ go into an infinite loop if the snake
     * currently fills the garden, but we'll leave discovery of this prize to a
     * truly excellent snake-player.
     * 
     */
    private void addRandomApple() {
        Coordinate newCoord = null;
        boolean found = false;
        while (!found) {
            // Choose a new location for our apple
            int newX = 1 + RNG.nextInt(mXTileCount - 2);
            int newY = 1 + RNG.nextInt(mYTileCount - 2);
            newCoord = new Coordinate(newX, newY);

            // Make sure it's not already under the snake
            boolean collision = false;
            /* TODO
            int snakelength = mSnakeTrail.size();
            for (int index = 0; index < snakelength; index++) {
                if (mSnakeTrail.get(index).equals(newCoord)) {
                    collision = true;
                }
            }
            */
            // if we're here and there's been no collision, then we have
            // a good location for an apple. Otherwise, we'll circle back
            // and try again
            found = !collision;
        }
        if (newCoord == null) {
            Log.e(TAG, "Somehow ended up with a null newCoord!");
        }
        mAppleList.add(newCoord);
    }


    /**
     * Handles the basic update loop, checking to see if we are in the running
     * state, determining if a move should be made, updating the snake's location.
     */
    public void update() {
        if (mMode == RUNNING) {
          /* TODO
            long now = System.currentTimeMillis();

            if (now - mLastMove > mMoveDelay) {
                clearTiles();
                updateWalls();
                updateSnake();
                updateApples();
                mLastMove = now;
            }
            */
            clearTiles();
            updateWalls();
            updateSnake();
            updateApples();
      try {
        game.tick();
      } catch (SnakeHitYardWallException e) {
        setMode(LOSE);
      }
          long mMoveDelay = game.getDelay();
            mRedrawHandler.sleep(mMoveDelay);
        }

    }

    /**
     * Draws some walls.
     * 
     */
    private void updateWalls() {
        for (int x = 0; x < mXTileCount; x++) {
            setTile(GREEN_STAR, x, 0);
            setTile(GREEN_STAR, x, mYTileCount - 1);
        }
        for (int y = 1; y < mYTileCount - 1; y++) {
            setTile(GREEN_STAR, 0, y);
            setTile(GREEN_STAR, mXTileCount - 1, y);
        }
    }

    /**
     * Draws some apples.
     * 
     */
    private void updateApples() {
        for (Coordinate c : mAppleList) {
            setTile(YELLOW_STAR, c.x, c.y);
        }
    }

    /**
     * Figure out which way the snake is going, see if he's run into anything (the
     * walls, himself, or an apple). If he's not going to die, we then add to the
     * front and subtract from the rear in order to simulate motion. If we want to
     * grow him, we don't subtract from the rear.
     * 
     */
    private void updateSnake() {
        // TODO boolean growSnake = false;

        // grab the snake by the head
        // TODO Coordinate head = mSnakeTrail.get(0);
        // TODO Coordinate newHead = new Coordinate(1, 1);

        Yard yard = this.game.getYard();
        Snake snake = yard.getSnake();

        /* TODO
        mDirection = mNextDirection;

        switch (mDirection) {
        case EAST: {
            newHead = new Coordinate(head.x + 1, head.y);
            break;
        }
        case WEST: {
            newHead = new Coordinate(head.x - 1, head.y);
            break;
        }
        case NORTH: {
            newHead = new Coordinate(head.x, head.y - 1);
            break;
        }
        case SOUTH: {
            newHead = new Coordinate(head.x, head.y + 1);
            break;
        }
        }
        */

        // Collision detection
        // For now we have a 1-square wall around the entire arena
        /* TODO
        if ((newHead.x < 1) || (newHead.y < 1) || (newHead.x > mXTileCount - 2)
                || (newHead.y > mYTileCount - 2)) {
            setMode(LOSE);
            return;

        }
        */

        // Look for collisions with itself
        /* TODO
        int snakelength = mSnakeTrail.size();
        for (int snakeindex = 0; snakeindex < snakelength; snakeindex++) {
            Coordinate c = mSnakeTrail.get(snakeindex);
            if (c.equals(newHead)) {
                setMode(LOSE);
                return;
            }
        }
        */

        // Look for apples
        int applecount = mAppleList.size();
        for (int appleindex = 0; appleindex < applecount; appleindex++) {
            Coordinate c = mAppleList.get(appleindex);
            Coordinates head = snake.getHeadCoordinates();
            if (c.x == head.x && c.y == head.y) {
            // TODO if (c.equals(newHead)) {
                mAppleList.remove(c);
                addRandomApple();
                
                mScore++;
                // TODO mMoveDelay *= 0.9;

                // TODO growSnake = true;
                snake.eat();
                
            }
        }

        // push a new head onto the ArrayList and pull off the tail
        /* TODO
        mSnakeTrail.add(0, newHead);
        // except if we want the snake to grow
        if (!growSnake) {
            mSnakeTrail.remove(mSnakeTrail.size() - 1);
        }
        */

        /* TODO
        int index = 0;
        for (Coordinate c : mSnakeTrail) {
            if (index == 0) {
                setTile(YELLOW_STAR, c.x, c.y);
            } else {
                setTile(RED_STAR, c.x, c.y);
            }
            index++;
        }
        */
        
        snake.render(new SnakeRenderer() {
      
      @Override
      public void renderHead(Coordinates headCoordinates, char direction) {
        setTile(YELLOW_STAR, headCoordinates.x, headCoordinates.y);        
      }
      
      @Override
      public void renderBody(Coordinates coordinates) {
        setTile(RED_STAR, coordinates.x, coordinates.y);
      }
    });

    }

    /**
     * Simple class containing two integer values and a comparison function.
     * There's probably something I should use instead, but this was quick and
     * easy to build.
     * 
     */
    private class Coordinate {
        public int x;
        public int y;

        public Coordinate(int newX, int newY) {
            x = newX;
            y = newY;
        }

        public boolean equals(Coordinate other) {
            if (x == other.x && y == other.y) {
                return true;
            }
            return false;
        }

        @Override
        public String toString() {
            return "Coordinate: [" + x + "," + y + "]";
        }
    }
    
}

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