游戏暂停/继续机制
由于原来的代码中在游戏运行时没有提供控制选项（比如暂停/继续），因此除非你死了，否则只能玩到底。我这里对代码进行一些修改，加入一个Option Menu来提供暂停/继续机制。
首先加入一个变量记录游戏当前状态
private
int
mState
=
SnakeView.READY;
然后重载onCreateOptionsMenu函数，创建一个控制菜单项，并对其进行处理，提供暂停/继续机制。
/*
* @see android.app.Activity#onOptionsItemSelected(android.view.MenuItem)
* @Author:phinecos
* @Date:2009-08-28
*/
@Override
public boolean onOptionsItemSelected(MenuItem item)
{
switch (item.getItemId())
{
case MENU_CONTROL:
{
if (mState == SnakeView.PAUSE)
{ // 此前状态是"停止"，则转为"运行"
mState = SnakeView.RUNNING;
mSnakeView.setMode(SnakeView.RUNNING);
item.setIcon(android.R.drawable.ic_media_pause).setTitle(R.string.cmd_pause);
}
else if (mState == SnakeView.RUNNING)
{ // 此前状态是"运行",则转为“暂停"
mState = SnakeView.PAUSE;
mSnakeView.setMode(SnakeView.PAUSE);
item.setIcon(android.R.drawable.ic_media_play).setTitle(R.string.cmd_run);
}
else if (mState == SnakeView.READY)
{ // 此前是"初始状态"，则转为"运行"
mState = SnakeView.RUNNING;
}
return true ;
}
}
return super .onOptionsItemSelected(item);
}
/*
* @see android.app.Activity#onOptionsItemSelected(android.view.MenuItem)
* @Author:phinecos
* @Date:2009-08-28
*/
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
super .onCreateOptionsMenu(menu);
menu.add( 0 , MENU_CONTROL, 0 , R.string.cmd_pause).setIcon(android.R.drawable.ic_media_pause);
return true ;
}
* @see android.app.Activity#onOptionsItemSelected(android.view.MenuItem)
* @Author:phinecos
* @Date:2009-08-28
*/
@Override
public boolean onOptionsItemSelected(MenuItem item)
{
switch (item.getItemId())
{
case MENU_CONTROL:
{
if (mState == SnakeView.PAUSE)
{ // 此前状态是"停止"，则转为"运行"
mState = SnakeView.RUNNING;
mSnakeView.setMode(SnakeView.RUNNING);
item.setIcon(android.R.drawable.ic_media_pause).setTitle(R.string.cmd_pause);
}
else if (mState == SnakeView.RUNNING)
{ // 此前状态是"运行",则转为“暂停"
mState = SnakeView.PAUSE;
mSnakeView.setMode(SnakeView.PAUSE);
item.setIcon(android.R.drawable.ic_media_play).setTitle(R.string.cmd_run);
}
else if (mState == SnakeView.READY)
{ // 此前是"初始状态"，则转为"运行"
mState = SnakeView.RUNNING;
}
return true ;
}
}
return super .onOptionsItemSelected(item);
}
/*
* @see android.app.Activity#onOptionsItemSelected(android.view.MenuItem)
* @Author:phinecos
* @Date:2009-08-28
*/
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
super .onCreateOptionsMenu(menu);
menu.add( 0 , MENU_CONTROL, 0 , R.string.cmd_pause).setIcon(android.R.drawable.ic_media_pause);
return true ;
}
修改后运行截图如下：
当然，这段代码还是有问题的，游戏刚开始时，必须先点击菜单确认，再按上方向键才能开始。（以后再来修改。。。）
穿墙贪食蛇
第二个修改是把这个普通的贪食蛇改成可以穿墙(呵呵，这样就可以不死了。。。)。想必要修改的就是撞墙检测那段代码？没错，就是下面这段！
//
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 ))
{ // 撞墙
setMode(LOSE);
return ;
}
// 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 ))
{ // 撞墙
setMode(LOSE);
return ;
}
原来的版本是发现撞墙时就直接判定为失败，我这里做个小小的修改，让它可以穿墙而去:
private
void
updateSnake()
{
boolean growSnake = false ;
// grab the snake by the head
Coordinate head = mSnakeTrail.get( 0 );
Coordinate newHead = new Coordinate( 1 , 1 );
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 ;
}
}
// 穿墙的处理
if (newHead.x == 0 )
{ // 穿左边的墙
newHead.x = mXTileCount - 2 ;
}
else if (newHead.y == 0 )
{ // 穿上面的墙
newHead.y = mYTileCount - 2 ;
}
else if (newHead.x == mXTileCount - 1 )
{ // 穿右边的墙
newHead.x = 1 ;
}
else if (newHead.y == mYTileCount - 1 )
{ // 穿下面的墙
newHead.y = 1 ;
}
// 判断是否撞到自己
int snakelength = mSnakeTrail.size();
for ( int snakeindex = 0 ; snakeindex < snakelength; snakeindex ++ )
{
Coordinate c = mSnakeTrail.get(snakeindex);
if (c.equals(newHead))
{
setMode(LOSE);
return ;
}
}
// 判断是否吃掉“苹果”
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 ++ ;
}
}
{
boolean growSnake = false ;
// grab the snake by the head
Coordinate head = mSnakeTrail.get( 0 );
Coordinate newHead = new Coordinate( 1 , 1 );
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 ;
}
}
// 穿墙的处理
if (newHead.x == 0 )
{ // 穿左边的墙
newHead.x = mXTileCount - 2 ;
}
else if (newHead.y == 0 )
{ // 穿上面的墙
newHead.y = mYTileCount - 2 ;
}
else if (newHead.x == mXTileCount - 1 )
{ // 穿右边的墙
newHead.x = 1 ;
}
else if (newHead.y == mYTileCount - 1 )
{ // 穿下面的墙
newHead.y = 1 ;
}
// 判断是否撞到自己
int snakelength = mSnakeTrail.size();
for ( int snakeindex = 0 ; snakeindex < snakelength; snakeindex ++ )
{
Coordinate c = mSnakeTrail.get(snakeindex);
if (c.equals(newHead))
{
setMode(LOSE);
return ;
}
}
// 判断是否吃掉“苹果”
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 ++ ;
}
}
其实修改后的代码非常简单，就是把新节点的值做些处理，让它移动到对应的行/列的头部或尾部即可。下面就是修改后的“穿墙”贪食蛇的运行截图：
全屏机制
游戏一般都是全屏的，原始代码也考虑到标题栏太过难看了，于是使用下面这句代码就去掉了标题栏：
requestWindowFeature(Window.FEATURE_NO_TITLE);
可还是没有达到全屏的效果，在Android1.5中实现全屏效果非常简单，只需要一句代码即可实现：
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
运行效果如下图所示：
