android---粒子雨效果的实现

刚学习了自定义view,就按照极客学院的教程做了粒子雨效果,主要用到绘画线条和多线程,其中的抽象类设计方法值得学习,

1.baseview主要是设定雨滴要实现的动作,只是先设定,也就是抽象方法,在子类中实现其方法
2.Rainitems封装雨滴类
3.Rainitems对雨滴集合创建到面板中,显示出来,具体实现就是在这个类中

一.baseview封装类,子类继承后实现方法即可

public abstract class BaseView extends View {

    private control thread;

    public BaseView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public BaseView(Context context) {
        super(context);
    }
    //封装,构造画面,子类继承后需要重写
    protected abstract void drawsub(Canvas canvas);
    //封装移动方法,子类继承后需要重写
    protected abstract void move();
    //封装的初始化方法
    protected abstract void init();
    @Override
    protected final void onDraw(Canvas canvas) {

        //启动线程
        if (thread ==null) {
            thread = new control();
            thread.start();
        }else {
            drawsub(canvas);
        }
    }

    public class control extends Thread{
        @Override
        public void run() {
            init();
            while(true){
                move();
                //相当于刷新画布
                postInvalidate();
                try {
                    sleep(30);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

}

二,Rainitem雨点类

public class RainItem {

    private int height;
    private int width;
    private float startX;
    private float startY;
    private float stopX;
    private float stopY;
    private float sizeX;
    private float sizeY;
    private float of = 0.5f;
    private Paint paint;
    private Random random = new Random();

    public RainItem(int height,int width) {
        this.height = height;
        this.width = width;
        init();
    }

    public void init() {

        //startx和y对应的分别是起止位置
        sizeX = 1 + random.nextInt(10);
        sizeY = 10 + random.nextInt(20);
        startX = random.nextInt(width);
        startY = random.nextInt(height);
        stopX = startX + sizeX;
        stopY = startY + sizeY;
        of = (float) (0.2 + random.nextFloat());
        paint = new Paint();
    }
    /**
     * 绘画雨滴
     * @param canvas
     */
    public void draw(Canvas canvas) {
        paint.setARGB(255, random.nextInt(255), random.nextInt(255), random.nextInt(255));
        canvas.drawLine(startX, startY, stopX, stopY, paint);
    }
    /**
     * 雨滴的移动行为
     */
    public void movestep() {
        //size*of这个是用来控制速度,所谓的速度就是线条增加的速度
        startX += sizeX*of;
        stopX += sizeX*of;

        startY += sizeY*of;
        stopY += sizeY*of;
        //如果超出边界则重新运行
        if (startY>height) {
            init();
        }
    }
}

三.Rainplay具体实现的类

public class Rainplay extends BaseView {

    List<RainItem> list = new ArrayList<RainItem>();
    //控制雨滴的数量
    private int num = 80;

    public Rainplay(Context context) {
        super(context);
    }

    public Rainplay(Context context, AttributeSet attrs) {
        super(context, attrs);
        //与xml链接起来
        TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.RainView);
        num = ta.getInteger(R.styleable.RainView_rainnum,80);
        ta.recycle();
    }
    @Override
    protected void drawsub(Canvas canvas) {
        for (RainItem item : list) {
            item.draw(canvas);
        }
    }

    @Override
    protected void move() {
        for (RainItem item : list) {
            item.movestep();
        }
    }
    /**
     * 因为获取长宽是放在layout之后才可以获取,所以需要
     * 放在线程里面初始化
     */
    @Override
    protected void init() {
        for (int i = 0; i < num; i++) {
            RainItem item = new RainItem(getHeight(), getWidth());
            list.add(item);
        }       
    }

}

四.value与xml文件

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name = "RainView">
        <attr name="rainnum" format="integer"/>
      </declare-styleable>
</resources>

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:an="http://schemas.android.com/apk/res/com.niuli.Rain"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
     >
    <com.niuli.Rain.Rainplay 
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#ff000000"
        an:rainnum = "100"/>
</FrameLayout>

效果图’

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