Android 气泡自由移动和漩涡

来源：互联网发布：exo在韩国的地位知乎编辑：程序博客网时间：2024/04/28 12:43
原理：
1.气泡自由移动，就是随机的在气泡的四个方向上（上下左右）移动一个距离。
2.漩涡向内收缩，其实就是使用圆的极坐标方程x = R*cos(theta) + centerX; y = R*sin(theta) + centerY;让R和theta都成为变量。
废话不多说直接上代码：
</pre><pre name="code" class="java">package com.stevens.ui.view;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.LinearGradient;import android.graphics.Paint;import android.graphics.Rect;import android.graphics.Shader;import android.os.SystemClock;import android.util.AttributeSet;import android.util.Log;import android.view.KeyEvent;import android.view.MotionEvent;import android.view.View;import java.util.ArrayList;import java.util.Random;public class BubbleView extends View implements Runnable {    private static final String TAG = "BubbleView";    private static final int NORTH = 0;    private static final int SOUTH = 1;    private static final int EAST = 2;    private static final int WEST = 3;    private static final int NORTH_WEST = 4;    private static final int NORTH_EAST = 5;    private static final int SOUTH_WEST = 6;    private static final int SOUTH_EAST = 7;    private boolean isInitBubble = false;    private static final int count = 10;    private int height, width;    private Rect viewRect;    Shader mShasder;    private Paint paint;    private boolean isRunning = true;    private Canvas canvas;    private ArrayList<Circle> bubbles = new ArrayList<Circle>();    private Random rand = new Random();    private boolean isChangeRunning = false;    private int frequency = 0;    public BubbleView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        init();    }    public BubbleView(Context context, AttributeSet attrs) {        super(context, attrs);        init();    }    public BubbleView(Context context) {        super(context);        init();    }    @Override    public void run() {        while (isRunning) {            SystemClock.sleep(10);            this.postInvalidate();        }    }    @Override    public boolean onKeyDown(int keyCode, KeyEvent event) {        switch (keyCode) {            case KeyEvent.KEYCODE_DPAD_CENTER:                break;            case KeyEvent.KEYCODE_BACK:                isRunning = false;                break;            case KeyEvent.KEYCODE_HOME:                isRunning = false;            default:                break;        }        return super.onKeyDown(keyCode, event);    }    @Override    public boolean onTouchEvent(MotionEvent event) {        // TODO Auto-generated method stub        switch (event.getAction()) {            case MotionEvent.ACTION_DOWN:                if (!isChangeRunning) {                    isChangeRunning = true;                } else {                    isChangeRunning = false;                }                break;            default:                break;        }        return super.onTouchEvent(event);    }    @Override    protected void onDraw(Canvas canvas) {        if (!isInitBubble) {            height = this.getHeight();            width = this.getWidth();            viewRect = new Rect(0, 0, width, height);            mShasder = new LinearGradient(0, 0, 0, height, new int[] {                    Color.GREEN, Color.BLUE            }, null, Shader.TileMode.CLAMP);            isInitBubble = true;            for (int i = 0; i < count; i++) {                bubbles.add(new Circle(rand.nextInt(width), rand.nextInt(height),                        rand.nextInt(30) + 20, rand.nextInt(60) + 40));            }        }        paint.reset();        paint.setShader(mShasder);        canvas.drawColor(Color.BLACK);        canvas.drawRect(viewRect, paint);        if (frequency % 5 == 0) {            for (Circle c : bubbles) {                if (isChangeRunning) {                    c.runBubble();                } else {                    c.increase();                }            }        }        for (Circle c : bubbles) {            c.draw(canvas, paint);        }        frequency++;        super.onDraw(canvas);    }    private void init() {        paint = new Paint();        this.setFocusable(true);        new Thread(this).start();    }    private class CircleCenterPoint {        private float x;        private float y;        public CircleCenterPoint(float x, float y) {            this.x = x;            this.y = y;        }        public float getX() {            return x;        }        public void setX(float x) {            this.x = x;        }        public float getY() {            return y;        }        public void setY(float y) {            this.y = y;        }        public boolean isOutOfView(float r) {            boolean isOutView = false;            if (x > width - r || x < r || y > height - r || y <= r) {                isOutView = true;            }            return isOutView;        }        public boolean isInCenterView(float r, float centerViewR) {            boolean isOutView = false;            if (x > width / 2 - centerViewR && x < width / 2 + centerViewR                    && y > height / 2 - centerViewR && y <= height / 2 + centerViewR) {                isOutView = true;            }            return isOutView;        }    }    private class Circle {        private CircleCenterPoint center;        private float r;        private int a;        private int aMax;        private double distance;        private double minDistance;        private int type = rand.nextInt(100);        private int count = 0;        private double delta = 0.1f;        private double theta = 0;        private boolean isInitDistance = false;        private double delta2 = 0.1f;        boolean isShouldDisapear = false;        public Circle(float x, float y, float r, int a) {            center = new CircleCenterPoint(x, y);            this.r = r;            this.a = a;            minDistance = rand.nextInt(100);        }        public void runBubble() {            if (!isInitDistance) {                isInitDistance = true;                float x = center.getX() - width / 2;                float y = center.getY() - height / 2;                distance = Math.sqrt((double) (x * x + y * y));                if (x > 0) {                    theta = Math.atan(y / x);                } else {                    theta = Math.atan(y / x) + Math.PI;                }            }            theta = theta + 0.1;            distance = getDistance(distance);            center.setY((float) (distance * Math.sin(theta)) + height / 2);            center.setX((float) (distance * Math.cos(theta)) + width / 2);        }        public void increase() {            if (isInitDistance) {                delta = 0.1f;                isInitDistance = false;            }            changeCenterPoint(center, type);            if (center.isOutOfView(r) || center.isInCenterView(r, 100f)) {                isShouldDisapear = true;            }        }        public void draw(Canvas canvas, Paint paint) {            count++;            if (count % ((type + 8) * 10) == 0) {                type = rand.nextInt(100);            }            if (isShouldDisapear) {                a--;                if (a <= 0) {                    isShouldDisapear = false;                    center.setX(rand.nextInt(width));                    center.setY(rand.nextInt(height));                    r = rand.nextInt(30) + 20;                    aMax = rand.nextInt(60) + 40;                }            } else {                if (a <= aMax) {                    a++;                } else {                    aMax = 0;                }            }            paint.reset();            paint.setColor(Color.WHITE);            paint.setAlpha(a);            canvas.drawCircle(center.getX(), center.getY(), r, paint);        }        private double getDistance(double distance) {            double result = distance;            delta = delta + 0.1;            result = result - delta * delta;            if (result < minDistance) {                result = minDistance;            }            return result;        }    }    private void changeCenterPoint(CircleCenterPoint center, int type) {        switch (type % 8) {            case NORTH:                center.setX(center.getX());                center.setY(center.getY() - rand.nextInt(4));                break;            case SOUTH:                center.setX(center.getX());                center.setY(center.getY() + rand.nextInt(4));                break;            case EAST:                center.setX(center.getX() + rand.nextInt(4));                center.setY(center.getY());                break;            case WEST:                center.setX(center.getX() - rand.nextInt(4));                center.setY(center.getY());                break;            case NORTH_WEST:                center.setX(center.getX() - rand.nextInt(4));                center.setY(center.getY() - rand.nextInt(4));                break;            case NORTH_EAST:                center.setX(center.getX() + rand.nextInt(4));                center.setY(center.getY() - rand.nextInt(4));                break;            case SOUTH_WEST:                center.setX(center.getX() + rand.nextInt(4));                center.setY(center.getY() + rand.nextInt(4));                break;            case SOUTH_EAST:                center.setX(center.getX() - rand.nextInt(4));                center.setY(center.getY() + rand.nextInt(4));                break;        }    }}
注意的问题：
1.这里的theta时候弧度，而非角度(高中的数学都还给数据老师了，很久以后才想明白^-^)。
2.由于直接使用随机值来计算气泡的下一个坐标，会发现气泡总是在一个位置停留很久，不是特别自然，这里让在跑随机在一个方向上多移动一会儿。
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