Comment puis-je utiliser le cadre de l'animation à l'intérieur de la toile?

Question

Je veux utiliser certaines animations comme rebondir à l'intérieur de ma toile. Est-il possible d'utiliser cette animation interpolateurs à l'intérieur?

Dans mon cas, j'ai envie de faire pivoter une image de 0 à 180 degrés avec un rebond à la fin.

Comment est-il possible?

Answer 1

L'Android de l'animation de la classe s'applique à des objets tels que des points de vue et mises en page. La toile est juste une surface de dessin qui soit à la partie de la Vue ou lié à une image bitmap. Dans onDraw dans un affichage personnalisé une image est dessinée sur le temps jusqu'à la prochaine invalider est appelée, ce qui signifie que vous devez dessiner votre animation image par image. Voici un exemple de la balle qui rebondit, qui tourne, qui pourront vous être utiles.

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();
    }
}

C'est juste une simple illustration, mais je voudrais utiliser surfaceView et lecteur des images à partir d'un autre thread, ce qui est un peu plus compliqué, mais une bonne façon de le faire lors de la prise des animations interactives comme les jeux etc. Voici un exemple avec un défilement de fond, et l'utilisateur peut déplacer la balle avec son doigt:

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);
                    }
                }
            }
        }
    }
}

Voici les images: