lunarview.java

android 例子中的LunarLander。很有代表意义

                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);
            }
        }

        /**
         * Resumes from a pause.
         */
        public void unpause() {
            // Move the real time clock up to now
            synchronized (mSurfaceHolder) {
                mLastTime = System.currentTimeMillis() + 100;
            }
            setState(STATE_RUNNING);
        }

        /**
         * Handles a key-down event.
         * 
         * @param keyCode the key that was pressed
         * @param msg the original event object
         * @return true
         */
        boolean doKeyDown(int keyCode, KeyEvent msg) {
            synchronized (mSurfaceHolder) {
                boolean okStart = false;
                if (keyCode == KeyEvent.KEYCODE_DPAD_UP) okStart = true;
                if (keyCode == KeyEvent.KEYCODE_DPAD_DOWN) okStart = true;
                if (keyCode == KeyEvent.KEYCODE_S) okStart = true;

                boolean center = (keyCode == KeyEvent.KEYCODE_DPAD_UP);

                if (okStart
                        && (mMode == STATE_READY || mMode == STATE_LOSE || mMode == STATE_WIN)) {
                    // ready-to-start -> start
                    doStart();
                    return true;
                } else if (mMode == STATE_PAUSE && okStart) {
                    // paused -> running
                    unpause();
                    return true;
                } else if (mMode == STATE_RUNNING) {
                    // center/space -> fire
                    if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER
                            || keyCode == KeyEvent.KEYCODE_SPACE) {
                        setFiring(true);
                        return true;
                        // left/q -> left
                    } else if (keyCode == KeyEvent.KEYCODE_DPAD_LEFT
                            || keyCode == KeyEvent.KEYCODE_Q) {
                        mRotating = -1;
                        return true;
                        // right/w -> right
                    } else if (keyCode == KeyEvent.KEYCODE_DPAD_RIGHT
                            || keyCode == KeyEvent.KEYCODE_W) {
                        mRotating = 1;
                        return true;
                        // up -> pause
                    } else if (keyCode == KeyEvent.KEYCODE_DPAD_UP) {
                        pause();
                        return true;
                    }
                }

                return false;
            }
        }

        /**
         * Handles a key-up event.
         * 
         * @param keyCode the key that was pressed
         * @param msg the original event object
         * @return true if the key was handled and consumed, or else false
         */
        boolean doKeyUp(int keyCode, KeyEvent msg) {
            boolean handled = false;

            synchronized (mSurfaceHolder) {
                if (mMode == STATE_RUNNING) {
                    if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER