Класс анимации Android применяется к таким объектам, как представления и макеты.Холст - это просто поверхность для рисования, которая является частью представления или связана с растровым изображением.В onDraw в пользовательском представлении отображается только один кадр за один раз, пока не будет вызван следующий недействительный результат, что означает, что вы должны рисовать анимацию кадр за кадром.Вот пример прыгающего шара, который вращается, что может оказаться полезным.
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();
}
}
Это просто простая иллюстрация, но я бы использовал SurfaceView и приводные кадры из другогонить, которая немного сложнее, но это правильный способ сделать при создании интерактивных анимаций, таких как игры и т. д. Вот пример с прокруткой фона, и пользователь может перемещать мяч пальцем:
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);
}
}
}
}
}
}
Вот изображения:
