九宫格

public class StreamSave extends Activity{ @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(new StreamSaveView(this)); } } class StreamSaveView extends SurfaceView implements Callback,Runnable{ private SurfaceHolder mSurfaceHolder; private Thread mThread; private boolean mFlag; private Paint mPaint; private Canvas mCanvas; private int mCurrentIndex; private int mScreenW; private int mScreenH; public StreamSaveView(Context context) { super(context); mSurfaceHolder=this.getHolder(); mSurfaceHolder.addCallback(this); mPaint=new Paint(); mPaint.setAntiAlias(true); setFocusable(true); } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { // TODO Auto-generated method stub } @Override public void surfaceCreated(SurfaceHolder holder) { mScreenW=this.getWidth(); mScreenH=this.getHeight(); mFlag=true; mThread=new Thread(this,"My Thread"); mThread.start(); } @Override public void surfaceDestroyed(SurfaceHolder holder) { mFlag=false; } @Override public void run() { while(mFlag){ long start=System.currentTimeMillis(); myDraw(); logic(); long end=System.currentTimeMillis(); if((end-start)<50){ try { Thread.sleep(50); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } private void logic() { // TODO Auto-generated method stub } private void myDraw() { try { mCanvas=mSurfaceHolder.lockCanvas(); if(mCanvas != null){ mCanvas.drawColor(Color.WHITE); mPaint.setColor(Color.BLACK); mPaint.setStyle(Paint.Style.STROKE); int tileW=mScreenW/3; int tileH=mScreenH/3; //Draw style box for (int indexX = 0; indexX < 3; indexX++) { for (int indexY = 0; indexY < 3; indexY++) { mCanvas.drawRect(indexX*tileW,indexY*tileH,(indexX+1)*tileW,(indexY+1)*tileH,mPaint); } } //Draw ball mPaint.setStyle(Paint.Style.FILL); mCanvas.drawCircle(mCurrentIndex%3*tileW+tileW/2, mCurrentIndex/3*tileH+tileH/2, 30, mPaint); } } catch (Exception e) { // TODO: handle exception }finally{ if(mCanvas != null){ mSurfaceHolder.unlockCanvasAndPost(mCanvas); } } } @Override public boolean onKeyDown(int keyCode, KeyEvent event) { switch(keyCode){ case KeyEvent.KEYCODE_DPAD_LEFT: if(mCurrentIndex>0){ mCurrentIndex--; }else mCurrentIndex=0; break; case KeyEvent.KEYCODE_DPAD_RIGHT: if(mCurrentIndex<9){ mCurrentIndex++; }else{ mCurrentIndex=8; } break; case KeyEvent.KEYCODE_DPAD_DOWN: if(mCurrentIndex<=5){ mCurrentIndex+=3; } break; case KeyEvent.KEYCODE_DPAD_UP: if(mCurrentIndex>=3){ mCurrentIndex-=3; } break; default: break; } return super.onKeyDown(keyCode, event); } }

问题一：

这是用绘画的方式实现九宫格，刚开始唯一比较难以理解的就是：mCanvas.drawCircle(mCurrentIndex%3*tileW+tileW/2, mCurrentIndex/3*tileH+tileH/2, 30, mPaint);

其实想想之前学习数据结构的时候，求行号是除以每一行的元素的个数，求列号是对一行的元素的个数取模，也就分别对应了y坐标和x坐标