Android特效--粒子效果之雨

1. 单个雨点的行为

2. 完善雨点的行为和构造下雨场景

3. 在XML中定义可以控制下雨的属性

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1. 单个雨点的行为： 一条线段在运动

起始点：startX ， startY;

终止点：stopX，  stopY;

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" alt="" />

自定义View的框架类

public abstract class BaseView extends View {

    Thread thread;

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

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

    @Override
    final protected void onDraw(Canvas canvas) {
        //禁止子类覆盖，用final
        if(thread == null ) {
            thread = new MyThread();
            thread.start();
        } else{
            drawSub(canvas);
        }
    }

    protected abstract void logic();
    protected abstract void drawSub(Canvas canvas);

    @Override
    final protected void onDetachedFromWindow() {
        // 离开屏幕时结束
        //onDetachedFromWindow在销毁资源（既销毁view）之后调用
        running = false;
        super.onDetachedFromWindow();
    }
    private boolean running = true;
    class MyThread extends Thread {
        @Override
        public void run() {
            while(running) {
                logic();
                postInvalidate(); //线程中更新绘制，重新调用onDraw方法
                try {
                    Thread.sleep(50); //速度太快肉眼看不到，要睡眠
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }
    }

}

自定义单个雨点RainView

public class RainView extends BaseView {

    private float startX = 0;
    private float startY = 0;  // Start Point
    private float stopX = 0;
    private float stopY = 0;  // Stop Point
    private float sizeX = 0;
    private float sizeY = 0;
    private Paint paint;

    public RainView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }

    public RainView(Context context, AttributeSet attrs) {
        super(context, attrs);
        sizeX = 10;
        sizeY = 30;
        //单个雨点的形状，用线段表示
        startX = 100;
        startY = 0;
        stopX = startX + sizeX;
        stopY = startY + sizeY;

        paint = new Paint();
        paint.setColor(0xffffffff);
    }

    @Override
    protected void logic() {
        // 让雨点运动
        float opt = 0.3f;
        startX += sizeX * opt;
        stopX += sizeX * opt;
        startY += sizeY * opt;
        stopY += sizeY * opt;

        // 雨点出了屏幕的时候让它回到起始点
        if(startY > getHeight() || startX > getWidth()){
            startX = 100;
            startY = 0;
            stopX = startX + sizeX;
            stopY = startY + sizeY;
        }
    }

    @Override
    protected void drawSub(Canvas canvas) {
        // drawSub 完成绘制操作
        canvas.drawLine(startX, startY, stopX, stopY, paint);
    }

}

在布局文件中使用

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.carloz.raineffect.MainActivity" >

    <com.carloz.raineffect.v1.single_rain.RainView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#ff000000" />

</FrameLayout>

效果如下：

2. 完善雨点的行为和构造下雨场景

aaarticlea/png;base64,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" alt="" />

2.1 将雨点 效果和 行为 抽象出来

* 雨点的速度和长度是可变的

* 雨点的倾斜角度是可变的

* 雨点的位置是可变的

public class RainItem {

    private int width;
    private int height;

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

    private float startX = 0;
    private float startY = 0; // Start Point
    private float stopX = 0;
    private float stopY = 0; // Stop Point
    private float sizeX = 0;
    private float sizeY = 0;
    private Paint paint;
    private float opt;
    private Random random;

    public void init() {
        // TODO Auto-generated method stub
        random = new Random();

        sizeX = 1 + random.nextInt(10); // 随机改变雨点的角度
        sizeY = 1 + random.nextInt(20);
        // 单个雨点的形状，用线段表示
        startX = random.nextInt(this.width);
        startY = random.nextInt(this.height); // 随机改变雨点的位置
        stopX = startX + sizeX;
        stopY = startY + sizeY;

        paint = new Paint();
        paint.setColor(0xffffffff);
    }

    public void draw(Canvas canvas) {
        canvas.drawLine(startX, startY, stopX, stopY, paint);
    }

    public void move() {
        // 让雨点运动
        opt = 0.2f + random.nextFloat(); // 随机改变雨点的速度和长度
        startX += sizeX * opt;
        stopX += sizeX * opt;
        startY += sizeY * opt;
        stopY += sizeY * opt;

        // 雨点出了屏幕的时候让它回到起始点
        if (startY > this.height || startX > this.width) {
            startX = random.nextInt(this.width);
            startY = random.nextInt(this.height);
            stopX = startX + sizeX;
            stopY = startY + sizeY;
        }
    }

}

2.2 定义多个雨点

在 添加抽象 BaseView 方法： protected abstract void init();

class MyThread extends Thread {
    @Override
    public void run() {
        init();
        while(running) {
            logic();
            postInvalidate(); //线程中更新绘制，重新调用onDraw方法
            try {
                Thread.sleep(50); //速度太快肉眼看不到，要睡眠
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

public class RainView extends BaseView {

    ArrayList<RainItem> rainList = new ArrayList<RainItem>();
    int size = 80;

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

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

    @Override
    protected void init() {
        // TODO Auto-generated method stub
        for (int i = 0; i < size; i++) {
            RainItem item = new RainItem(getWidth(), getHeight());
            rainList.add(item);
        }
    }

    @Override
    protected void logic() {
        for (RainItem item : rainList) {
            item.move();
        }
    }

    @Override
    protected void drawSub(Canvas canvas) {
        // drawSub 完成绘制操作
        for (RainItem item : rainList) {
            item.draw(canvas);
        }
    }

}

效果如下：

3. 在XML中定义可以控制下雨的属性