android 게임 개발 입문: 뱀 소스 코드 분석

package com.example.android.snake;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.View;


/**
 * TileView: a View-variant designed for handling arrays of "icons" or other
 * drawables.
 * 
 */

public class TileView extends View {

    /**
     * Parameters controlling the size of the tiles and their range within view.
     * Width/Height are in pixels, and Drawables will be scaled to fit to these
     * dimensions. X/Y Tile Counts are the number of tiles that will be drawn.
     */

    protected static int mTileSize; //  tile        

    protected static int mXTileCount; //        X         
    protected static int mYTileCount;//        Y         

    private static int mXOffset; //    ， pixel 。
    private static int mYOffset;


    /**
     * A hash that maps integer handles specified by the subclasser to the
     * drawable that will be used for that reference
     *         bitmap 。  resetTiles，loadTile，              。
     *           
     */
    private Bitmap[] mTileArray;    

    /**
     * A two-dimensional array of integers in which the number represents the
     * index of the tile that should be drawn at that locations
     *          tile       tile。
     *              。
     *   setTile、clearTile            。 
     * 
     */
    private int[][] mTileGrid; 

    //  ，canvas     ，    Paint  。
    private final Paint mPaint = new Paint();

    
    public TileView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        //  TypedArray，   attrs.xml  TileView      tileSize 。  ： http://weizhulin.blog.51cto.com/1556324/311453
        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TileView);
        mTileSize = a.getInt(R.styleable.TileView_tileSize, 12);
        a.recycle();
    }

    public TileView(Context context, AttributeSet attrs) {
        super(context, attrs);
        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TileView);
        mTileSize = a.getInt(R.styleable.TileView_tileSize, 12);
        a.recycle();
    }

    
    
    /**
     * Rests the internal array of Bitmaps used for drawing tiles, and
     * sets the maximum index of tiles to be inserted
     *     mTileArray，          。
     *        
     * @param tilecount
     */
    public void resetTiles(int tilecount) {
    	mTileArray = new Bitmap[tilecount];
    }

    
    /*
     *           ，    tile       。
     */
    
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        mXTileCount = (int) Math.floor(w / mTileSize);
        mYTileCount = (int) Math.floor(h / mTileSize);

        //mXOffset mYOffset        。
        mXOffset = ((w - (mTileSize * mXTileCount)) / 2);
        mYOffset = ((h - (mTileSize * mYTileCount)) / 2);

        mTileGrid = new int[mXTileCount][mYTileCount];
        clearTiles();
    }

    
    /**
     * Function to set the specified Drawable as the tile for a particular
     * integer key.
     *                 。
     *                   mTileArray   
     * @param key
     * @param tile
     */
    public void loadTile(int key, Drawable tile) {
        //       Drawable   bitmap    。                        ，
    	// drawable  ，       bitmap  ，       。  ，        bitmap   。
    	Bitmap bitmap = Bitmap.createBitmap(mTileSize, mTileSize, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        tile.setBounds(0, 0, mTileSize, mTileSize);
        tile.draw(canvas);
        
        mTileArray[key] = bitmap;
    }

    /**
     * Used to indicate that a particular tile (set with loadTile and referenced
     * by an integer) should be drawn at the given x/y coordinates during the
     * next invalidate/draw cycle.
     *                
     *    ，mTileGrid             。
     * @param tileindex
     * @param x
     * @param y
     */
    public void setTile(int tileindex, int x, int y) {
        mTileGrid[x][y] = tileindex;
    }

    /**
     * Resets all tiles to 0 (empty)
     *       。
     *       。
     *       setTile()。
     */
    public void clearTiles() {
        for (int x = 0; x < mXTileCount; x++) {
            for (int y = 0; y < mYTileCount; y++) {
                setTile(0, x, y);
            }
        }
    }

/*
 *                   ！
 * @see android.view.View#onDraw(android.graphics.Canvas)
 */
    @Override
    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        for (int x = 0; x < mXTileCount; x += 1) {
            for (int y = 0; y < mYTileCount; y += 1) {
                if (mTileGrid[x][y] > 0) {
                    canvas.drawBitmap(mTileArray[mTileGrid[x][y]], 
                    		mXOffset + x * mTileSize,
                    		mYOffset + y * mTileSize,
                    		mPaint);
                }
            }
        }
    }

}

package com.example.android.snake;

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

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.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.
     *          。
     */
    private int mDirection = NORTH;
    private int mNextDirection = NORTH;
    private static final int NORTH = 1;
    private static final int SOUTH = 2;
    private static final int EAST = 3;
    private static final int WEST = 4;

    /**
     * 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;   //       。
    private long mMoveDelay = 600;  //        。      600ms，        ，  9 
               					//            。
    
    /**
     * mLastMove: tracks the absolute time when the snake last moved, and is used
     * to determine if a move should be made based on mMoveDelay.
     *            。
     *  mMoveDelay                 。
     */
    private long mLastMove;
    
    
    /**
     * mStatusText: text shows to the user in some run states
     *          TextView
     */
    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.
     *     ，                 。
     *        ，     ，      ，     ，       。
     */
    private ArrayList mSnakeTrail = new ArrayList();
    private ArrayList mAppleList = new ArrayList();

    /**
     * Everyone needs a little randomness in their life
     *       。         。 addRandomApple()   。
     */
    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.
     *  Handler        。
     *      Handler ？       android      （  UI         ～）
     *              ，     ～
     */
    private RefreshHandler mRedrawHandler = new RefreshHandler();

    class RefreshHandler extends Handler {

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

        //       UI  ，         。
        public void sleep(long delayMillis) {
        	this.removeMessages(0); //      ，Handler         
            sendMessageDelayed(obtainMessage(0), delayMillis); //       ,  handler
        }
    };


    
    public SnakeView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initSnakeView();  //     ，   ，     ～
   }

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

    //   SnakeView ，  ，            。
    private void initSnakeView() {
        setFocusable(true); //    ，                   。  focus      。

        //        ，          。
        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() {
        //              。
    	mSnakeTrail.clear();
        mAppleList.clear();

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

        // Two apples to start with
        addRandomApple();
        addRandomApple();

        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...】
     *       ，    Bundle      。 saveState()。
     * Bundle       。
     *               ，           ，          int  。
     */
    private int[] coordArrayListToArray(ArrayList 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));
        map.putInt("mDirection", Integer.valueOf(mDirection));
        map.putInt("mNextDirection", Integer.valueOf(mNextDirection));
        map.putLong("mMoveDelay", Long.valueOf(mMoveDelay));
        map.putLong("mScore", Long.valueOf(mScore));
        map.putIntArray("mSnakeTrail", coordArrayListToArray(mSnakeTrail));

        return map;
    }

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

        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
     *       。 saveState()    
     * @param icicle a Bundle containing the game state
     */
    public void restoreState(Bundle icicle) {
        setMode(PAUSE);

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

    /*
     * handles key events in the game. Update the direction our snake is traveling
     * based on the DPAD. Ignore events that would cause the snake to immediately
     * turn back on itself.
     *      。
     *       android        。
     *                           - -#
     * @see android.view.View#onKeyDown(int, android.os.KeyEvent)
     */
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent msg) {
    	//          。          ，      。           ～
        if (keyCode == KeyEvent.KEYCODE_DPAD_UP) {
            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(); //update()           ，         。
                return (true);
            }

            if (mMode == PAUSE) {
                /*
                 * If the game is merely paused, we should just continue where
                 * we left off.
                 */
                setMode(RUNNING);
                update();
                return (true);
            }

            if (mDirection != SOUTH) {  //                     ，     
                mNextDirection = NORTH;  
            }
            return (true);
        }

        if (keyCode == KeyEvent.KEYCODE_DPAD_DOWN) {
            if (mDirection != NORTH) {
                mNextDirection = SOUTH;
            }
            return (true);
        }

        if (keyCode == KeyEvent.KEYCODE_DPAD_LEFT) {
            if (mDirection != EAST) {
                mNextDirection = WEST;
            }
            return (true);
        }

        if (keyCode == KeyEvent.KEYCODE_DPAD_RIGHT) {
            if (mDirection != WEST) {
                mNextDirection = EAST;
            }
            return (true);
        }

        return super.onKeyDown(keyCode, msg);
    }

    /**
     * Sets the TextView that will be used to give information (such as "Game
     * Over" to the user.
     *               。          。Snake      ，       textview.
     */
    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); //     ， TextView           。
            update(); //   ， initGame   update(),    ～      update       ，
             			//     mLastMove   mMoveDelay    。   Update()   。
            			//  ，    ，     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.
     *            。                ～     bug，    
     *                      。
     *              mApplist    。
     */
    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;
            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.
     *       。         、       ，      update()    。
     */
    public void update() {
        if (mMode == RUNNING) {
            long now = System.currentTimeMillis();

            if (now - mLastMove > mMoveDelay) {  //                        
            						//       mMode   ， update()       。
                clearTiles(); 		//       。		
                updateWalls();      //      
                updateSnake(); 	   //                 
                updateApples();   //                  
                mLastMove = now;
            }
            mRedrawHandler.sleep(mMoveDelay);   //  Handler          
        }

    }

    /**
     * Draws some walls.
     *  setTile    
     */
    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() {
        boolean growSnake = false;  //         。          。

        // grab the snake by the head
        Coordinate head = mSnakeTrail.get(0);  //     ，          。
        Coordinate newHead = new Coordinate(1, 1); //         ，   newHead。         。
        				//      Coordinate newHead  ？          。
        				//            switch    newHead   ，          ～
        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
        //    
        if ((newHead.x < 1) || (newHead.y < 1) || (newHead.x > mXTileCount - 2)
                || (newHead.y > mYTileCount - 2)) {
            setMode(LOSE);
            return;

        }

        // Look for collisions with itself
        //     
        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);
            if (c.equals(newHead)) {
                mAppleList.remove(c);
                addRandomApple();
                
                mScore++;
                mMoveDelay *= 0.9;

                growSnake = true;
            }
        }

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

        //      
        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++;
        }

    }

    /**
     * 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.
     *        。      XY  。
     */
    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 + "]";
        }
    }
    
}

package com.example.android.snake;

import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.widget.TextView;

/**
 * Snake: a simple game that everyone can enjoy.
 * This is an implementation of the classic Game "Snake", in which you control a
 * serpent roaming around the garden looking for apples. Be careful, though,
 * because when you catch one, not only will you become longer, but you'll move
 * faster. Running into yourself or the walls will end the game.
 */

public class Snake extends Activity {


    private SnakeView mSnakeView;
    
    private static String ICICLE_KEY = "snake-view";

    /**
     * Called when Activity is first created. Turns off the title bar, sets up
     * the content views, and fires up the SnakeView.
     * 
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.snake_layout);

        mSnakeView = (SnakeView) findViewById(R.id.snake);
        mSnakeView.setTextView((TextView) findViewById(R.id.text));

        if (savedInstanceState == null) {
            // We were just launched -- set up a new game
            mSnakeView.setMode(SnakeView.READY);
        } else {
            // We are being restored
            Bundle map = savedInstanceState.getBundle(ICICLE_KEY);
            if (map != null) {
                mSnakeView.restoreState(map);
            } else {
                mSnakeView.setMode(SnakeView.PAUSE);
            }
        }
    }

    @Override
    protected void onPause() {
        super.onPause();
        // Pause the game along with the activity
        mSnakeView.setMode(SnakeView.PAUSE);
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        //Store the game state
        outState.putBundle(ICICLE_KEY, mSnakeView.saveState());
    }

}