效果图

实现过程

1. 绘制心形并为其添加抖动动画效果

绘制心形采用的是参数方程:
在这里插入图片描述
如果需要在xml中使用该View, 设置心形的颜色, 还需要自定义属性:
src/main/res/values/attrs.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="HeartView">
        <attr name="heart_color" format="color" />
    </declare-styleable>
</resources>

使用自定义属性, 需要在View中去解析, View解析自定义属性一般是在第二种构造函数中.

public class HeartView extends View {
    // 默认值 宽高和颜色
    private int mWidth = 50;
    private int mHeight = 50;
    private int heartColor = Color.parseColor("#db5860");

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

    public HeartView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        if (context != null) {
            // 解析xml中的对应属性
            TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.HeartView);
            heartColor = ta.getColor(R.styleable.HeartView_heart_color, Color.parseColor("#db5860"));
            ta.recycle();
        }
    }

    public HeartView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public HeartView(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    public void draw(Canvas canvas) {
        super.draw(canvas);
        mHeight = getHeight();
        mWidth = getWidth();
        // drawCoordinateSystem(canvas);
        Paint paint = new Paint();
        paint.setAntiAlias(true);
        paint.setColor(heartColor);
        Path path = new Path();
        float x = 0, y = 0;
        path.moveTo((float) mWidth / 2, (float) mHeight / 2);
        for (int t = 0; t < 10000; t++) {
            x = (float) getWidth() * 1 / 50 * (float) (16 * Math.pow(Math.sin(t), 3));
            y =
                    (float) getWidth() * 1 / 50 * (float) (13 * Math.cos(t) - 5 * Math.cos(2 * t) - 2 * Math.cos(3 * t) - Math.cos(4 * t));
            path.lineTo(x + (float) mWidth / 2, -y + (float) mHeight / 2);
        }
        canvas.drawPath(path, paint);
    }

    /**
     * 画坐标系
     *
     * @param canvas 画布
     */
    private void drawCoordinateSystem(Canvas canvas) {
        Paint paint = new Paint();
        paint.setStrokeWidth(5);
        paint.setColor(Color.parseColor("#263055"));
        canvas.drawLine(0, (float) mHeight / 2, mWidth, (float) mHeight / 2, paint);
        canvas.drawLine((float) mWidth / 2, 0, (float) mWidth / 2, mHeight, paint);
        Path path = new Path();
        path.addCircle((float) mWidth / 2, (float) mHeight / 2, 10, Path.Direction.CW);
        path.close();
        canvas.drawPath(path, paint);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        HearTrembleAni hearTrembleAni = new HearTrembleAni();
        hearTrembleAni.setDuration(1000);
        hearTrembleAni.setRepeatCount(2);
        this.startAnimation(hearTrembleAni);
        return true;
    }

    /**
     * 抖动效果动画
     *
     * @see <a href="https://blog.csdn.net/keke921231/article/details/78889491">android 控件动画效果实现</a>
     */
    static class HearTrembleAni extends Animation {
        @Override
        protected void applyTransformation(float interpolatedTime, Transformation t) {
            t.getMatrix().setTranslate(
                    (float) Math.sin(interpolatedTime * 150) * 2,
                    (float) Math.sin(interpolatedTime * 150) * 2
            );
            super.applyTransformation(interpolatedTime, t);
        }
    }

    public void setHeartColor(int heartColor) {
        this.heartColor = heartColor;
    }
}

心形的绘制效果如下:

2. 自定义Layout

在点击位置添加心形, 同时开启线程控制下落.

public class HeartLayout extends FrameLayout {
    ExecutorService mExecutorService = new ScheduledThreadPoolExecutor(30);

    public HeartLayout(@NonNull Context context) {
        super(context);
    }

    public HeartLayout(@NonNull Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public HeartLayout(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public HeartLayout(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float rawX = event.getX();
        float rawY = event.getRawY();
        drawHeart(rawX, rawY);
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                drawHeart(rawX, rawY);
                break;
            default:
                break;
        }
        return super.onTouchEvent(event);
    }

    private void drawHeart(float rawX, float rawY) {
        HeartView heartView = new HeartView(this.getContext());
        LayoutParams layoutParams = new LayoutParams(50, 50);
        layoutParams.topMargin = (int) rawY - 50;
        layoutParams.leftMargin = (int) rawX - 25;
        addView(heartView, layoutParams);
        mExecutorService.execute(() -> {
            for (int i = 0; i < getHeight(); i += 5) {
                try {
                    Thread.sleep(50);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                heartView.setTranslationY(i);
            }
        });
    }
}