The file containing the source code shown below is located in the corresponding directory in <sdk>/samples/android-<version>/...
/*
* Copyright (C) 2010 The Android开源工程
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.example.android.apis.animation;
// Need the following import to get access to the app resources, since this
// class is in a sub-package.
import android.graphics.drawable.ColorDrawable;
import com.example.android.apis.R;
import android.animation.*;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RadialGradient;
import android.graphics.Shader;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.OvalShape;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.DecelerateInterpolator;
import android.widget.LinearLayout;
import java.util.ArrayList;
public class BouncingBalls extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.bouncing_balls);
LinearLayout container = (LinearLayout) findViewById(R.id.container);
container.addView(new MyAnimationView(this));
}
public class MyAnimationView extends View {
private static final int RED = 0xffFF8080;
private static final int BLUE = 0xff8080FF;
private static final int CYAN = 0xff80ffff;
private static final int GREEN = 0xff80ff80;
public final ArrayList<ShapeHolder> balls = new ArrayList<ShapeHolder>();
AnimatorSet animation = null;
public MyAnimationView(Context context) {
super(context);
// Animate background color
// Note that setting the background color will automatically invalidate the
// view, so that the animated color, and the bouncing balls, get redisplayed on
// every frame of the animation.
ValueAnimator colorAnim = ObjectAnimator.ofInt(this, "backgroundColor", RED, BLUE);
colorAnim.setDuration(3000);
colorAnim.setEvaluator(new ArgbEvaluator());
colorAnim.setRepeatCount(ValueAnimator.INFINITE);
colorAnim.setRepeatMode(ValueAnimator.REVERSE);
colorAnim.start();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (event.getAction() != MotionEvent.ACTION_DOWN &&
event.getAction() != MotionEvent.ACTION_MOVE) {
return false;
}
ShapeHolder newBall = addBall(event.getX(), event.getY());
// Bouncing animation with squash and stretch
float startY = newBall.getY();
float endY = getHeight() - 50f;
float h = (float)getHeight();
float eventY = event.getY();
int duration = (int)(500 * ((h - eventY)/h));
ValueAnimator bounceAnim = ObjectAnimator.ofFloat(newBall, "y", startY, endY);
bounceAnim.setDuration(duration);
bounceAnim.setInterpolator(new AccelerateInterpolator());
ValueAnimator squashAnim1 = ObjectAnimator.ofFloat(newBall, "x", newBall.getX(),
newBall.getX() - 25f);
squashAnim1.setDuration(duration/4);
squashAnim1.setRepeatCount(1);
squashAnim1.setRepeatMode(ValueAnimator.REVERSE);
squashAnim1.setInterpolator(new DecelerateInterpolator());
ValueAnimator squashAnim2 = ObjectAnimator.ofFloat(newBall, "width", newBall.getWidth(),
newBall.getWidth() + 50);
squashAnim2.setDuration(duration/4);
squashAnim2.setRepeatCount(1);
squashAnim2.setRepeatMode(ValueAnimator.REVERSE);
squashAnim2.setInterpolator(new DecelerateInterpolator());
ValueAnimator stretchAnim1 = ObjectAnimator.ofFloat(newBall, "y", endY,
endY + 25f);
stretchAnim1.setDuration(duration/4);
stretchAnim1.setRepeatCount(1);
stretchAnim1.setInterpolator(new DecelerateInterpolator());
stretchAnim1.setRepeatMode(ValueAnimator.REVERSE);
ValueAnimator stretchAnim2 = ObjectAnimator.ofFloat(newBall, "height",
newBall.getHeight(), newBall.getHeight() - 25);
stretchAnim2.setDuration(duration/4);
stretchAnim2.setRepeatCount(1);
stretchAnim2.setInterpolator(new DecelerateInterpolator());
stretchAnim2.setRepeatMode(ValueAnimator.REVERSE);
ValueAnimator bounceBackAnim = ObjectAnimator.ofFloat(newBall, "y", endY,
startY);
bounceBackAnim.setDuration(duration);
bounceBackAnim.setInterpolator(new DecelerateInterpolator());
// Sequence the down/squash&stretch/up animations
AnimatorSet bouncer = new AnimatorSet();
bouncer.play(bounceAnim).before(squashAnim1);
bouncer.play(squashAnim1).with(squashAnim2);
bouncer.play(squashAnim1).with(stretchAnim1);
bouncer.play(squashAnim1).with(stretchAnim2);
bouncer.play(bounceBackAnim).after(stretchAnim2);
// Fading animation - remove the ball when the animation is done
ValueAnimator fadeAnim = ObjectAnimator.ofFloat(newBall, "alpha", 1f, 0f);
fadeAnim.setDuration(250);
fadeAnim.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
balls.remove(((ObjectAnimator)animation).getTarget());
}
});
// Sequence the two animations to play one after the other
AnimatorSet animatorSet = new AnimatorSet();
animatorSet.play(bouncer).before(fadeAnim);
// Start the animation
animatorSet.start();
return true;
}
private ShapeHolder addBall(float x, float y) {
OvalShape circle = new OvalShape();
circle.resize(50f, 50f);
ShapeDrawable drawable = new ShapeDrawable(circle);
ShapeHolder shapeHolder = new ShapeHolder(drawable);
shapeHolder.setX(x - 25f);
shapeHolder.setY(y - 25f);
int red = (int)(Math.random() * 255);
int green = (int)(Math.random() * 255);
int blue = (int)(Math.random() * 255);
int color = 0xff000000 | red << 16 | green << 8 | blue;
Paint paint = drawable.getPaint(); //new Paint(Paint.ANTI_ALIAS_FLAG);
int darkColor = 0xff000000 | red/4 << 16 | green/4 << 8 | blue/4;
RadialGradient gradient = new RadialGradient(37.5f, 12.5f,
50f, color, darkColor, Shader.TileMode.CLAMP);
paint.setShader(gradient);
shapeHolder.setPaint(paint);
balls.add(shapeHolder);
return shapeHolder;
}
@Override
protected void onDraw(Canvas canvas) {
for (int i = 0; i < balls.size(); ++i) {
ShapeHolder shapeHolder = balls.get(i);
canvas.save();
canvas.translate(shapeHolder.getX(), shapeHolder.getY());
shapeHolder.getShape().draw(canvas);
canvas.restore();
}
}
}
}