我如何使用canvas内的animation框架？
我想使用某些animation，例如在canvas内反弹。 可以在里面使用animation插值器吗？
在我的情况下，我想旋转一个图像从0到180度，最后反弹。
这怎么可能？
Androidanimation类适用于视图和布局等对象。 canvas只是一个绘图的表面，它既可以是视图的一部分，也可以链接到位图。 在自定义视图中的onDraw中，只有一个帧被绘制，直到下一个invalidate被调用，这意味着您必须逐帧绘制您的animation。 这是一个旋转的球的例子，你可能会觉得有用。
import android.app.Activity; import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.os.Bundle; import android.text.format.Time; import android.view.View; public class StartActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(new BallBounce(this)); } } class BallBounce extends View { int screenW; int screenH; int X; int Y; int initialY ; int ballW; int ballH; int angle; float dY; float acc; Bitmap ball, bgr; public BallBounce(Context context) { super(context); ball = BitmapFactory.decodeResource(getResources(),R.drawable.football); //load a ball image bgr = BitmapFactory.decodeResource(getResources(),R.drawable.sky_bgr); //load a background ballW = ball.getWidth(); ballH = ball.getHeight(); acc = 0.2f; //acceleration dY = 0; //vertical speed initialY = 100; //Initial vertical position. angle = 0; //Start value for rotation angle. } @Override public void onSizeChanged (int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); screenW = w; screenH = h; bgr = Bitmap.createScaledBitmap(bgr, w, h, true); //Resize background to fit the screen. X = (int) (screenW /2) - (ballW / 2) ; //Centre ball into the centre of the screen. Y = initialY; } @Override public void onDraw(Canvas canvas) { super.onDraw(canvas); //Draw background. canvas.drawBitmap(bgr, 0, 0, null); //Compute roughly ball speed and location. Y+= (int) dY; //Increase or decrease vertical position. if (Y > (screenH - ballH)) { dY=(-1)*dY; //Reverse speed when bottom hit. } dY+= acc; //Increase or decrease speed. //Increase rotating angle. if (angle++ >360) angle =0; //Draw ball canvas.save(); //Save the position of the canvas. canvas.rotate(angle, X + (ballW / 2), Y + (ballH / 2)); //Rotate the canvas. canvas.drawBitmap(ball, X, Y, null); //Draw the ball on the rotated canvas. canvas.restore(); //Rotate the canvas back so that it looks like ball has rotated. //Call the next frame. invalidate(); } } 这只是一个简单的例子，但我会使用surfaceView和驱动来自另一个线程的帧，这是一个更复杂，但一个正确的方法来做交互animation，如游戏等。这是一个滚动背景的例子，用户可以用手指移动球：
import android.app.Activity; import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Matrix; import android.graphics.Paint; import android.graphics.Rect; import android.os.Bundle; import android.view.MotionEvent; import android.view.SurfaceHolder; import android.view.SurfaceView; public class SurfaceViewActivity extends Activity { BallBounces ball; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); ball = new BallBounces(this); setContentView(ball); } } class BallBounces extends SurfaceView implements SurfaceHolder.Callback { GameThread thread; int screenW; //Device's screen width. int screenH; //Devices's screen height. int ballX; //Ball x position. int ballY; //Ball y position. int initialY ; float dY; //Ball vertical speed. int ballW; int ballH; int bgrW; int bgrH; int angle; int bgrScroll; int dBgrY; //Background scroll speed. float acc; Bitmap ball, bgr, bgrReverse; boolean reverseBackroundFirst; boolean ballFingerMove; //Measure frames per second. long now; int framesCount=0; int framesCountAvg=0; long framesTimer=0; Paint fpsPaint=new Paint(); //Frame speed long timeNow; long timePrev = 0; long timePrevFrame = 0; long timeDelta; public BallBounces(Context context) { super(context); ball = BitmapFactory.decodeResource(getResources(),R.drawable.football); //Load a ball image. bgr = BitmapFactory.decodeResource(getResources(),R.drawable.sky_bgr); //Load a background. ballW = ball.getWidth(); ballH = ball.getHeight(); //Create a flag for the onDraw method to alternate background with its mirror image. reverseBackroundFirst = false; //Initialise animation variables. acc = 0.2f; //Acceleration dY = 0; //vertical speed initialY = 100; //Initial vertical position angle = 0; //Start value for the rotation angle bgrScroll = 0; //Background scroll position dBgrY = 1; //Scrolling background speed fpsPaint.setTextSize(30); //Set thread getHolder().addCallback(this); setFocusable(true); } @Override public void onSizeChanged (int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); //This event-method provides the real dimensions of this custom view. screenW = w; screenH = h; bgr = Bitmap.createScaledBitmap(bgr, w, h, true); //Scale background to fit the screen. bgrW = bgr.getWidth(); bgrH = bgr.getHeight(); //Create a mirror image of the background (horizontal flip) - for a more circular background. Matrix matrix = new Matrix(); //Like a frame or mould for an image. matrix.setScale(-1, 1); //Horizontal mirror effect. bgrReverse = Bitmap.createBitmap(bgr, 0, 0, bgrW, bgrH, matrix, true); //Create a new mirrored bitmap by applying the matrix. ballX = (int) (screenW /2) - (ballW / 2) ; //Centre ball X into the centre of the screen. ballY = -50; //Centre ball height above the screen. } //*************************************** //************* TOUCH ***************** //*************************************** @Override public synchronized boolean onTouchEvent(MotionEvent ev) { switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: { ballX = (int) ev.getX() - ballW/2; ballY = (int) ev.getY() - ballH/2; ballFingerMove = true; break; } case MotionEvent.ACTION_MOVE: { ballX = (int) ev.getX() - ballW/2; ballY = (int) ev.getY() - ballH/2; break; } case MotionEvent.ACTION_UP: ballFingerMove = false; dY = 0; break; } return true; } @Override public void onDraw(Canvas canvas) { super.onDraw(canvas); //Draw scrolling background. Rect fromRect1 = new Rect(0, 0, bgrW - bgrScroll, bgrH); Rect toRect1 = new Rect(bgrScroll, 0, bgrW, bgrH); Rect fromRect2 = new Rect(bgrW - bgrScroll, 0, bgrW, bgrH); Rect toRect2 = new Rect(0, 0, bgrScroll, bgrH); if (!reverseBackroundFirst) { canvas.drawBitmap(bgr, fromRect1, toRect1, null); canvas.drawBitmap(bgrReverse, fromRect2, toRect2, null); } else{ canvas.drawBitmap(bgr, fromRect2, toRect2, null); canvas.drawBitmap(bgrReverse, fromRect1, toRect1, null); } //Next value for the background's position. if ( (bgrScroll += dBgrY) >= bgrW) { bgrScroll = 0; reverseBackroundFirst = !reverseBackroundFirst; } //Compute roughly the ball's speed and location. if (!ballFingerMove) { ballY += (int) dY; //Increase or decrease vertical position. if (ballY > (screenH - ballH)) { dY=(-1)*dY; //Reverse speed when bottom hit. } dY+= acc; //Increase or decrease speed. } //Increase rotating angle if (angle++ >360) angle =0; //DRAW BALL //Rotate method one /* Matrix matrix = new Matrix(); matrix.postRotate(angle, (ballW / 2), (ballH / 2)); //Rotate it. matrix.postTranslate(ballX, ballY); //Move it into x, y position. canvas.drawBitmap(ball, matrix, null); //Draw the ball with applied matrix. */// Rotate method two canvas.save(); //Save the position of the canvas matrix. canvas.rotate(angle, ballX + (ballW / 2), ballY + (ballH / 2)); //Rotate the canvas matrix. canvas.drawBitmap(ball, ballX, ballY, null); //Draw the ball by applying the canvas rotated matrix. canvas.restore(); //Rotate the canvas matrix back to its saved position - only the ball bitmap was rotated not all canvas. //*/ //Measure frame rate (unit: frames per second). now=System.currentTimeMillis(); canvas.drawText(framesCountAvg+" fps", 40, 70, fpsPaint); framesCount++; if(now-framesTimer>1000) { framesTimer=now; framesCountAvg=framesCount; framesCount=0; } } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { } @Override public void surfaceCreated(SurfaceHolder holder) { thread = new GameThread(getHolder(), this); thread.setRunning(true); thread.start(); } @Override public void surfaceDestroyed(SurfaceHolder holder) { boolean retry = true; thread.setRunning(false); while (retry) { try { thread.join(); retry = false; } catch (InterruptedException e) { } } } class GameThread extends Thread { private SurfaceHolder surfaceHolder; private BallBounces gameView; private boolean run = false; public GameThread(SurfaceHolder surfaceHolder, BallBounces gameView) { this.surfaceHolder = surfaceHolder; this.gameView = gameView; } public void setRunning(boolean run) { this.run = run; } public SurfaceHolder getSurfaceHolder() { return surfaceHolder; } @Override public void run() { Canvas c; while (run) { c = null; //limit frame rate to max 60fps timeNow = System.currentTimeMillis(); timeDelta = timeNow - timePrevFrame; if ( timeDelta < 16) { try { Thread.sleep(16 - timeDelta); } catch(InterruptedException e) { } } timePrevFrame = System.currentTimeMillis(); try { c = surfaceHolder.lockCanvas(null); synchronized (surfaceHolder) { //call methods to draw and process next fame gameView.onDraw(c); } } finally { if (c != null) { surfaceHolder.unlockCanvasAndPost(c); } } } } } }
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