有關SurfaceView 我們將通過三個系統 自帶的例子 來深入掌握Android繪圖必會的SurfaceView，今天我們以SDK中的Sample 游戲 lunarlander中的LunarView具體實現，Android123建議大家導入該游戲工程到你的Eclipse 然后自己編譯 先玩一下這個游戲，然后再看代碼 比較好理解。
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class LunarView extends SurfaceView implements SurfaceHolder.Callback {
class LunarThread extends Thread {
/*
* Difficulty setting constants
*/
public static final int DIFFICULTY_EASY = 0;
public static final int DIFFICULTY_HARD = 1;
public static final int DIFFICULTY_MEDIUM = 2;
/*
* Physics constants
*/
public static final int PHYS_DOWN_ACCEL_SEC = 35;
public static final int PHYS_FIRE_ACCEL_SEC = 80;
public static final int PHYS_FUEL_INIT = 60;
public static final int PHYS_FUEL_MAX = 100;
public static final int PHYS_FUEL_SEC = 10;
public static final int PHYS_SLEW_SEC = 120; // degrees/second rotate
public static final int PHYS_SPEED_HYPERSPACE = 180;
public static final int PHYS_SPEED_INIT = 30;
public static final int PHYS_SPEED_MAX = 120;
/*
* State-tracking constants
*/
public static final int STATE_LOSE = 1;
public static final int STATE_PAUSE = 2;
public static final int STATE_READY = 3;
public static final int STATE_RUNNING = 4;
public static final int STATE_WIN = 5;
/*
* Goal condition constants
*/
public static final int TARGET_ANGLE = 18; // > this angle means crash
public static final int TARGET_BOTTOM_PADDING = 17; // px below gear
public static final int TARGET_PAD_HEIGHT = 8; // how high above ground
public static final int TARGET_SPEED = 28; // > this speed means crash
public static final double TARGET_WIDTH = 1.6; // width of target
/*
* UI constants (i.e. the speed & fuel bars)
*/
public static final int UI_BAR = 100; // width of the bar(s)
public static final int UI_BAR_HEIGHT = 10; // height of the bar(s)
private static final String KEY_DIFFICULTY = "mDifficulty";
private static final String KEY_DX = "mDX";
private static final String KEY_DY = "mDY";
private static final String KEY_FUEL = "mFuel";
private static final String KEY_GOAL_ANGLE = "mGoalAngle";
private static final String KEY_GOAL_SPEED = "mGoalSpeed";
private static final String KEY_GOAL_WIDTH = "mGoalWidth";
private static final String KEY_GOAL_X = "mGoalX";
private static final String KEY_HEADING = "mHeading";
private static final String KEY_LANDER_HEIGHT = "mLanderHeight";
private static final String KEY_LANDER_WIDTH = "mLanderWidth";
private static final String KEY_WINS = "mWinsInARow";
private static final String KEY_X = "mX";
private static final String KEY_Y = "mY";
/*
* Member (state) fields
*/
/** The drawable to use as the background of the animation canvas */
private Bitmap mBackgroundImage;
/**
* Current height of the surface/canvas.
*
* @see #setSurfaceSize
*/
private int mCanvasHeight = 1;
/**
* Current width of the surface/canvas.
*
* @see #setSurfaceSize
*/
private int mCanvasWidth = 1;
/** What to draw for the Lander when it has crashed */
private Drawable mCrashedImage;
/**
* Current difficulty -- amount of fuel, allowed angle, etc. Default is
* MEDIUM.
*/
private int mDifficulty;
/** Velocity dx. */
private double mDX;
/** Velocity dy. */
private double mDY;
/** Is the engine burning? */
private boolean mEngineFiring;
/** What to draw for the Lander when the engine is firing */
private Drawable mFiringImage;
/** Fuel remaining */
private double mFuel;
/** Allowed angle. */
private int mGoalAngle;
/** Allowed speed. */
private int mGoalSpeed;
/** Width of the landing pad. */
private int mGoalWidth;
/** X of the landing pad. */
private int mGoalX;
/** Message handler used by thread to interact with TextView */
private Handler mHandler;
/**
* Lander heading in degrees, with 0 up, 90 right. Kept in the range
* 0..360.
*/
private double mHeading;
/** Pixel height of lander image. */
private int mLanderHeight;
/** What to draw for the Lander in its normal state */
private Drawable mLanderImage;
/** Pixel width of lander image. */
private int mLanderWidth;
/** Used to figure out elapsed time between frames */
private long mLastTime;
/** Paint to draw the lines on screen. */
private Paint mLinePaint;
/** "Bad" speed-too-high variant of the line color. */
private Paint mLinePaintBad;
/** The state of the game. One of READY, RUNNING, PAUSE, LOSE, or WIN */
private int mMode;
/** Currently rotating, -1 left, 0 none, 1 right. */
private int mRotating;
/** Indicate whether the surface has been created & is ready to draw */
private boolean mRun = false;
/** Scratch rect object. */
private RectF mScratchRect;
/** Handle to the surface manager object we interact with */
private SurfaceHolder mSurfaceHolder;
/** Number of wins in a row. */
private int mWinsInARow;
/** X of lander center. */
private double mX;
/** Y of lander center. */
private double mY;
public LunarThread(SurfaceHolder surfaceHolder, Context context,
Handler handler) {
// get handles to some important objects
mSurfaceHolder = surfaceHolder;
mHandler = handler;
mContext = context;
Resources res = context.getResources();
// cache handles to our key sprites & other drawables
mLanderImage = context.getResources().getDrawable(
R.drawable.lander_plain);
mFiringImage = context.getResources().getDrawable(
R.drawable.lander_firing);
mCrashedImage = context.getResources().getDrawable(
R.drawable.lander_crashed);
// load background image as a Bitmap instead of a Drawable b/c
// we don't need to transform it and it's faster to draw this way
mBackgroundImage = BitmapFactory.decodeResource(res,
R.drawable.earthrise);
// Use the regular lander image as the model size for all sprites
mLanderWidth = mLanderImage.getIntrinsicWidth();
mLanderHeight = mLanderImage.getIntrinsicHeight();
// Initialize paints for speedometer
mLinePaint = new Paint();
mLinePaint.setAntiAlias(true);
mLinePaint.setARGB(255, 0, 255, 0);
mLinePaintBad = new Paint();
mLinePaintBad.setAntiAlias(true);
mLinePaintBad.setARGB(255, 120, 180, 0);
mScratchRect = new RectF(0, 0, 0, 0);
mWinsInARow = 0;
mDifficulty = DIFFICULTY_MEDIUM;
// initial show-up of lander (not yet playing)
mX = mLanderWidth;
mY = mLanderHeight * 2;
mFuel = PHYS_FUEL_INIT;
mDX = 0;
mDY = 0;
mHeading = 0;
mEngineFiring = true;
}
/**
* Starts the game, setting parameters for the current difficulty.
*/
public void doStart() {
synchronized (mSurfaceHolder) {
// First set the game for Medium difficulty
mFuel = PHYS_FUEL_INIT;
mEngineFiring = false;
mGoalWidth = (int) (mLanderWidth * TARGET_WIDTH);
mGoalSpeed = TARGET_SPEED;
mGoalAngle = TARGET_ANGLE;
int speedInit = PHYS_SPEED_INIT;
// Adjust difficulty params for EASY/HARD
if (mDifficulty == DIFFICULTY_EASY) {
mFuel = mFuel * 3 / 2;
mGoalWidth = mGoalWidth * 4 / 3;
mGoalSpeed = mGoalSpeed * 3 / 2;
mGoalAngle = mGoalAngle * 4 / 3;
speedInit = speedInit * 3 / 4;
} else if (mDifficulty == DIFFICULTY_HARD) {
mFuel = mFuel * 7 / 8;
mGoalWidth = mGoalWidth * 3 / 4;
mGoalSpeed = mGoalSpeed * 7 / 8;
speedInit = speedInit * 4 / 3;
}
// pick a convenient initial location for the lander sprite
mX = mCanvasWidth / 2;
mY = mCanvasHeight - mLanderHeight / 2;
// start with a little random motion
mDY = Math.random() * -speedInit;
mDX = Math.random() * 2 * speedInit - speedInit;
mHeading = 0;
// Figure initial spot for landing, not too near center
while (true) {
mGoalX = (int) (Math.random() * (mCanvasWidth - mGoalWidth));
if (Math.abs(mGoalX - (mX - mLanderWidth / 2)) > mCanvasHeight / 6)
break;
}
mLastTime = System.currentTimeMillis() + 100;
setState(STATE_RUNNING);
}
}
/**
* Pauses the physics update & animation.
*/
public void pause() {
synchronized (mSurfaceHolder) {
if (mMode == STATE_RUNNING) setState(STATE_PAUSE);
}
}
/**
* Restores game state from the indicated Bundle. Typically called when
* the Activity is being restored after having been previously
* destroyed.
*
* @param savedState Bundle containing the game state
*/
public synchronized void restoreState(Bundle savedState) {
synchronized (mSurfaceHolder) {
setState(STATE_PAUSE);
mRotating = 0;
mEngineFiring = false;
mDifficulty = savedState.getInt(KEY_DIFFICULTY);
mX = savedState.getDouble(KEY_X);
mY = savedState.getDouble(KEY_Y);
mDX = savedState.getDouble(KEY_DX);
mDY = savedState.getDouble(KEY_DY);
mHeading = savedState.getDouble(KEY_HEADING);
mLanderWidth = savedState.getInt(KEY_LANDER_WIDTH);
mLanderHeight = savedState.getInt(KEY_LANDER_HEIGHT);
mGoalX = savedState.getInt(KEY_GOAL_X);
mGoalSpeed = savedState.getInt(KEY_GOAL_SPEED);
mGoalAngle = savedState.getInt(KEY_GOAL_ANGLE);
mGoalWidth = savedState.getInt(KEY_GOAL_WIDTH);
mWinsInARow = savedState.getInt(KEY_WINS);
mFuel = savedState.getDouble(KEY_FUEL);
}
}
@Override
public void run() {
while (mRun) {
Canvas c = null;
try {
c = mSurfaceHolder.lockCanvas(null);
synchronized (mSurfaceHolder) {
if (mMode == STATE_RUNNING) updatePhysics();
doDraw(c);
}
} finally {
// do this in a finally so that if an exception is thrown
// during the above, we don't leave the Surface in an
// inconsistent state
if (c != null) {
mSurfaceHolder.unlockCanvasAndPost(c);
}
}
}
}
/**
* Dump game state to the provided Bundle. Typically called when the
* Activity is being suspended.
*
* @return Bundle with this view's state
*/
public Bundle saveState(Bundle map) {
synchronized (mSurfaceHolder) {
if (map != null) {
map.putInt(KEY_DIFFICULTY, Integer.valueOf(mDifficulty));
map.putDouble(KEY_X, Double.valueOf(mX));
map.putDouble(KEY_Y, Double.valueOf(mY));
map.putDouble(KEY_DX, Double.valueOf(mDX));
map.putDouble(KEY_DY, Double.valueOf(mDY));
map.putDouble(KEY_HEADING, Double.valueOf(mHeading));
map.putInt(KEY_LANDER_WIDTH, Integer.valueOf(mLanderWidth));
map.putInt(KEY_LANDER_HEIGHT, Integer
.valueOf(mLanderHeight));
map.putInt(KEY_GOAL_X, Integer.valueOf(mGoalX));
map.putInt(KEY_GOAL_SPEED, Integer.valueOf(mGoalSpeed));
map.putInt(KEY_GOAL_ANGLE, Integer.valueOf(mGoalAngle));
map.putInt(KEY_GOAL_WIDTH, Integer.valueOf(mGoalWidth));
map.putInt(KEY_WINS, Integer.valueOf(mWinsInARow));
map.putDouble(KEY_FUEL, Double.valueOf(mFuel));
}
}
return map;
}
/**
* Sets the current difficulty.
*
* @param difficulty
*/
public void setDifficulty(int difficulty) {
synchronized (mSurfaceHolder) {
mDifficulty = difficulty;
}
}
/**
* Sets if the engine is currently firing.
*/
public void setFiring(boolean firing) {
synchronized (mSurfaceHolder) {
mEngineFiring = firing;
}
}
/**
* Used to signal the thread whether it should be running or not.
* Passing true allows the thread to run; passing false will shut it
* down if it's already running. Calling start() after this was most
* recently called with false will result in an immediate shutdown.
*
* @param b true to run, false to shut down
*/
public void setRunning(boolean b) {
mRun = b;
}
/**
* Sets the game mode. That is, whether we are running, paused, in the
* failure state, in the victory state, etc.
*
* @see #setState(int, CharSequence)
* @param mode one of the STATE_* constants
*/
public void setState(int mode) {
synchronized (mSurfaceHolder) {
setState(mode, null);
}
}
/**
* Sets the game mode. That is, whether we are running, paused, in the
* failure state, in the victory state, etc.
*
* @param mode one of the STATE_* constants
* @param message string to add to screen or null
*/
public void setState(int mode, CharSequence message) {
/*
* This method optionally can cause a text message to be displayed
* to the user when the mode changes. Since the View that actually
* renders that text is part of the main View hierarchy and not
* owned by this thread, we can't touch the state of that View.
* Instead we use a Message + Handler to relay commands to the main
* thread, which updates the user-text View.
*/
synchronized (mSurfaceHolder) {
mMode = mode;
if (mMode == STATE_RUNNING) {
Message msg = mHandler.obtainMessage();
Bundle b = new Bundle();
b.putString("text", "");
b.putInt("viz", View.INVISIBLE);
msg.setData(b);
mHandler.sendMessage(msg);
} else {
mRotating = 0;
mEngineFiring = false;
Resources res = mContext.getResources();
CharSequence str = "";
if (mMode == STATE_READY)
str = res.getText(R.string.mode_ready);
else if (mMode == STATE_PAUSE)
str = res.getText(R.string.mode_pause);
else if (mMode == STATE_LOSE)
str = res.getText(R.string.mode_lose);
else if (mMode == STATE_WIN)
str = res.getString(R.string.mode_win_prefix)
+ mWinsInARow + " "
+ res.getString(R.string.mode_win_suffix);
if (message != null) {
str = message + "\n" + str;
}
if (mMode == STATE_LOSE) mWinsInARow = 0;
Message msg = mHandler.obtainMessage();
Bundle b = new Bundle();
b.putString("text", str.toString());
b.putInt("viz", View.VISIBLE);
msg.setData(b);
mHandler.sendMessage(msg);
}
}
}
/* Callback invoked when the surface dimensions change. */
public void setSurfaceSize(int width, int height) {
// synchronized to make sure these all change atomically
synchronized (mSurfaceHolder) {
mCanvasWidth = width;
mCanvasHeight = height;
// don't forget to resize the background image
mBackgroundImage = mBackgroundImage.createScaledBitmap(
mBackgroundImage, width, height, true);
}
}
本文來自CSDN博客，轉載請標明出處：http://blog.csdn.net/JavaTiger427/archive/2010/11/25/6034565.aspx
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學海無涯