Android实现花瓣飘落效果的步骤

2024-04-02 19:04:59 167人浏览安东尼

摘要

目录效果展示实现原理实现步骤完整代码展示效果展示实现原理首先需要生成绘制小花的坐标点，坐标点的横坐标是根据控件的宽度随机生成的，而纵坐标则设置为小花图片高度的负值（

效果展示

实现原理

首先需要生成绘制小花的坐标点，坐标点的横坐标是根据控件的宽度随机生成的，而纵坐标则设置为小花图片高度的负值（这样可以实现小花从屏幕外进入）。
将这些点存储到集合当中。
遍历集合根据点的位置绘制小花
绘制完后不断增加各个点的纵坐标

实现步骤

1.定义变量将变量初始化


    private SurfaceHolder mHolder;
    private boolean mFlag = true;//绘制小花线程的开关标志
    private ArrayList<PointF> mFlowers;//小花点的坐标集合
    private Random mRandom;//负责随机数生成
    private Bitmap mBitmap;//小花的图案

    public FlowerView(Context context) {
        super(context);
        init();
    }

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

    public FlowerView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }
    private void init(){
        mHolder = getHolder();
        mHolder.addCallback(this);
        //设置背景透明
        this.setZOrderOnTop(true);
        mHolder.setFORMat(PixelFormat.TRANSLUCENT);

        mFlowers = new ArrayList<>();
        mRandom = new Random();

        mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_hua);

    }

2.实现添加花朵坐标点的方法



    private void addFlower(){
        PointF point = new PointF();
        point.x=mRandom.nextInt(getWidth());//根据控件宽度随机生成X轴坐标
        point.y=-mBitmap.getHeight();//纵坐标设置为小花图像的负值（产生从屏幕外进入的效果）
        mFlowers.add(point);//将坐标点添加进集合
    }

3.实现SurfaceHolder.Callback及Runnable接口


public class FlowerView extends SurfaceView implements SurfaceHolder.Callback,Runnable

4.在run方法中实现绘制逻辑


 @Override
    public void run() {
        while (mFlag){
            try {
                Thread.sleep(80);//控制小花的下落速度
                canvas canvas = mHolder.lockCanvas();
                PointF pointF = null;
                //清屏操作（否则会残留一些无用图像）
                if(canvas!=null){
                    canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
                }else {
                    continue;
                }
                for(PointF point: mFlowers){
                    pointF = point;
                    canvas.drawBitmap(mBitmap,pointF.x,pointF.y,null);
                    int i = mRandom.nextInt(getHeight()/50)+getHeight()/50;//修改雨滴线的纵坐标，使其看起来在下雨
                    pointF.y=pointF.y+i;
                }
                mHolder.unlockCanvasAndPost(canvas);
                addFlower();
                //当绘制点的纵坐标大于控件高度时，将该点移除
                if(mFlowers.size()>0&&pointF!=null&&pointF.y>=getHeight()){
                    mFlowers.remove(pointF);
                }

            }catch (Exception e){}
        }
    }

5.在SurfaceHolder.Callback的回调方法中开启绘制线程


 @Override
    public void surfaceCreated(SurfaceHolder holder) {
        mFlag = true;//surface创建时将线程开关打开
        new Thread(this).start();//开启线程绘制
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        mFlowers.clear();//当控件发生改变时清除之前的绘制点
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        mFlag = false;//当surface销毁时关掉绘制线程
    }

完整代码展示


public class FlowerView extends SurfaceView implements SurfaceHolder.Callback,Runnable{
    private SurfaceHolder mHolder;
    private boolean mFlag = true;//绘制小花线程的开关标志
    private ArrayList<PointF> mFlowers;//小花点的坐标集合
    private Random mRandom;//负责随机数生成
    private Bitmap mBitmap;//小花的图案

    public FlowerView(Context context) {
        super(context);
        init();
    }

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

    public FlowerView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }
    private void init(){
        mHolder = getHolder();
        mHolder.addCallback(this);
        //设置背景透明
        this.setZOrderOnTop(true);
        mHolder.setFormat(PixelFormat.TRANSLUCENT);

        mFlowers = new ArrayList<>();
        mRandom = new Random();

        mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_hua);

    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        mFlag = true;
        new Thread(this).start();
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        mFlowers.clear();
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        mFlag = false;
    }

    @Override
    public void run() {
        while (mFlag){
            try {
                Thread.sleep(80);
                Canvas canvas = mHolder.lockCanvas();
                PointF pointF = null;
                //清屏操作
                if(canvas!=null){
                    canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
                }else {
                    continue;
                }
                for(PointF point: mFlowers){
                    pointF = point;
                    canvas.drawBitmap(mBitmap,pointF.x,pointF.y,null);
                    int i = mRandom.nextInt(getHeight()/50)+getHeight()/50;//修改雨滴线的纵坐标，使其看起来在下雨
                    pointF.y=pointF.y+i;
                }
                mHolder.unlockCanvasAndPost(canvas);
                addFlower();
                if(mFlowers.size()>0&&pointF!=null&&pointF.y>=getHeight()){
                    mFlowers.remove(pointF);
                }

            }catch (Exception e){}
        }
    }

    
    private void addFlower(){
        PointF point = new PointF();
        point.x=mRandom.nextInt(getWidth());
        point.y=-mBitmap.getHeight();
        mFlowers.add(point);
    }
}

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