Android自定義view--SurfaceView實現墨跡天氣的風車效果
SurfaceView也是繼承自View,它和我們以前接觸到的View(Button、TextView等)最大的不同是,SurfaceView可以有一個單獨的線程進行繪製,這個線程區別於UI線程(主線程),因此SurfaceView繪製並不佔用主線程資源。
SurfaceView實現通常是自定義,繼承SurfaceView並實現SurfaceHolder.Callback接口。使用SurfaceView,所有的繪圖工作必須得在Surface
被創建之後才能開始,所以Callback 中的surfaceCreated 和surfaceDestroyed 就成了繪圖處理代碼的邊界。
實現SurfaceHolder.Callback接口需要重寫的方法:
//在surface的大小發生改變時激發
(1)public void surfaceChanged(SurfaceHolder holder,int format,int width,int height){}
//在創建時激發,一般在這裏調用畫圖的線程。
(2)public void surfaceCreated(SurfaceHolder holder){}
//銷燬時激發,一般在這裏將畫圖的線程停止、釋放。
(3)public void surfaceDestroyed(SurfaceHolder holder) {}
SurfaceHolder有幾個重要方法:
//鎖定畫布,一般在鎖定後就可以通過其返回的畫布對象Canvas,在其上面畫圖等操作了。
(1)、abstract Canvas lockCanvas();
// 鎖定畫布的某個區域進行畫圖等..因爲畫完圖後,會調用下面的unlockCanvasAndPost來改變顯示內容。
// 相對部分內存要求比較高的遊戲來說,可以不用重畫dirty外的其它區域的像素,可以提高速度。
(2)、abstract Canvas lockCanvas(Rect dirty);
// 結束鎖定畫圖,並提交改變。(3)、abstract void unlockCanvasAndPost(Canvas canvas);
//給SurfaceView當前的持有者一個回調對象。
(4)、abstract void addCallback(SurfaceHolder.Callback callback);
下面使用SurfaceView實現墨跡天氣的風車效果:
- public class WindmillView extends SurfaceView implements
- SurfaceHolder.Callback, Runnable {
- private SurfaceHolder holder;
- private boolean isRunning = true;
- /**
- * 屏幕的像素
- */
- private int screenWidth;
- private int screenHeiht;
- private Bitmap windPoint;
- /**
- * 風車圖片
- */
- private Bitmap Windmill;
- /**
- * 背景圖片
- */
- private Bitmap viewBg;
- public WindmillView(Context context) {
- super(context);
- this.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT,
- LayoutParams.MATCH_PARENT));
- holder = getHolder();
- holder.addCallback(this);
- holder.setFormat(PixelFormat.RGBA_8888); // 頂層繪製SurfaceView設成透明
- getViewSize(context);
- LoadWindmillImage();
- }
- private void LoadWindmillImage() {
- viewBg = BitmapFactory.decodeResource(getResources(), R.drawable.bg_na);
- Windmill = BitmapFactory.decodeResource(getResources(),
- R.drawable.na_windmill);
- windPoint = BitmapFactory.decodeResource(getResources(),
- R.drawable.na_point);
- float percent = percentumW();
- Log.v("icers", screenWidth + "");
- int _witdh = (int) (250 / percent);//250是風車基點左側像素
- Log.v("icers", _witdh + "");
- Windmill = Bitmap.createScaledBitmap(Windmill, _witdh * 2, _witdh * 2,
- true);
- }
- // 獲取屏幕的分辨率
- private void getViewSize(Context context) {
- DisplayMetrics metrics = new DisplayMetrics();
- WindowManager windowManager = (WindowManager) context
- .getSystemService(Context.WINDOW_SERVICE);
- windowManager.getDefaultDisplay().getMetrics(metrics);
- this.screenHeiht = metrics.heightPixels;
- this.screenWidth = metrics.widthPixels;
- Log.d("Windmill", "Windmill:"+screenHeiht+"|"+screenWidth);
- }
- /**
- * 獲取背景圖和風車的比率 ,從而根據這個比例改變各個手機上面的風車圖片大小
- *
- *
- * @return
- */
- private float percentumW() {
- float bg_width = viewBg.getWidth();
- return bg_width/screenWidth ;
- }
- /**
- * 獲取背景圖和風車的比率 ,從而根據這個比例改變各個手機上面的風車圖片大小
- *
- *
- * @return
- */
- private float percentumH() {
- float bg_height = viewBg.getHeight();
- return bg_height/(screenHeiht);
- }
- @Override
- public void run() {
- float rotate = 0;// 旋轉角度變量
- while (isRunning) {
- Log.i("icer", "Running");
- Canvas canvas = null;
- synchronized (this) {
- try {
- canvas = holder.lockCanvas();
- if (canvas != null) {
- Paint paint = new Paint();
- paint.setAntiAlias(true);
- // 對圖片抗鋸齒
- paint.setFilterBitmap(true);
- RectF rect = new RectF(0, 0, screenWidth, screenHeiht
- );
- canvas.drawBitmap(viewBg, null, rect, paint);
- Matrix matrix = new Matrix();
- matrix.postRotate((rotate += 2) % 360f,
- Windmill.getWidth() / 2,
- Windmill.getHeight() / 2);
- int _dy = (int) (500 /percentumH()); //500是風車基點到背景定點的像素
- matrix.postTranslate(0, (_dy - (Windmill.getHeight()/2)));
- canvas.drawBitmap(Windmill, matrix, paint);
- int _dx = (int) (250 / percentumW());//250是風車基點左側像素
- canvas.drawBitmap(windPoint,_dx-windPoint.getWidth()/2,_dy-windPoint.getHeight()/2,paint);
- Thread.sleep(3);
- }
- } catch (InterruptedException e) {
- // TODO Auto-generated catch block
- e.printStackTrace();
- } finally {
- if (canvas != null) {
- holder.unlockCanvasAndPost(canvas);
- }
- }
- }
- }
- }
- public void setRunning(boolean state) {
- isRunning = state;
- }
- @Override
- public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
- // TODO Auto-generated method stub
- }
- @Override
- public void surfaceCreated(SurfaceHolder arg0) {
- new Thread(this).start();
- }
- @Override
- public void surfaceDestroyed(SurfaceHolder arg0) {
- // TODO Auto-generated method stub
- isRunning = false;
- }
- }
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
- requestWindowFeature(Window.FEATURE_NO_TITLE);
- WindmillView view=new WindmillView(this);
- setContentView(view);
- }
整個過程:繼承SurfaceView並實現SurfaceHolder.Callback接口 ----> SurfaceView.getHolder()獲得SurfaceHolder對象---->SurfaceHolder.lockCanvas()獲得Canvas對象並鎖定畫布----> Canvas繪畫 ---->SurfaceHolder.unlockCanvasAndPost(Canvas canvas)結束鎖定畫圖,並提交改變,將圖形顯示。