android 仿花椒送花效果

今天写一个单个的,明天写一个很多那种花向上运动的效果,单个的很简单,就是绘制一个二阶或者三阶贝塞尔曲线,然后不断的去改变这个离曲线起点位置的值,就可以求出坐标,这个都是api给我们提供好了的,我们只负责调就行,如果对Path不熟悉的话,要先去看下path是怎么回事,path是在绘制界是很重要的一个类,代码如下：

package com.lovebeisaier;
import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PathMeasure;
import android.util.AttributeSet;
import android.view.View;
/**
 * Created by admin on 2016/12/29.
 */
public class StarView extends View {
    private Paint paint;
    private Path path;
    private Bitmap bitmap = null;
    private PathMeasure pathMeasure;
    private float distance = 0;
    private float[] pos;//数组存放x,y坐标
    private int width;
    private int height;
    private ValueAnimator valueAnimator;
    public StarView(Context context) {
        this(context,null);
    }
    public StarView(Context context, AttributeSet attrs) {
        this(context, attrs,0);
    }
    public StarView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        bitmap = BitmapFactory.decodeResource(getResources(),R.mipmap.pl_red);
        initPaint();
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        initPath(w,h);
        width =w;
        height = h;
        initAnim();
    }
    private void initAnim() {
        valueAnimator = ValueAnimator.ofFloat(0,pathMeasure.getLength());
        valueAnimator.setDuration(3000);
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener(){
            @Override
            public void onAnimationUpdate(ValueAnimator valueAnimator) {
                distance = (float) valueAnimator.getAnimatedValue();
                invalidate();
            }
        });
    }
    private void initPath(int w,int h) {
        path = new Path();
        path.moveTo(w/2-bitmap.getWidth()/2,h-bitmap.getHeight()/2);
        path.quadTo(100,100,400,10);
        pathMeasure = new PathMeasure(path,false);
        pos = new float[2];
    }
    private void initPaint() {
        paint = new Paint();
        paint.setStrokeWidth(2);
        paint.setStyle(Paint.Style.STROKE);
        paint.setAntiAlias(true);
        paint.setColor(Color.RED);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        pathMeasure.getPosTan(distance,pos,null);
        canvas.drawPath(path,paint);
        canvas.drawBitmap(bitmap,pos[0]-bitmap.getWidth()/2,pos[1],paint);
    }
    public void startAnim(){
        valueAnimator.start();
    }
    public void stopAnim(){
        if(valueAnimator.isRunning()){
            valueAnimator.cancel();
        }
    }
}

调用：

package com.lovebeisaier;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity {
    private StarView view_star;
    private Button button;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        view_star = (StarView) findViewById(R.id.view_star);
        button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                view_star.startAnim();
            }
        });
    }
}

布局：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="开始执行动画"
        />
    <com.lovebeisaier.StarView
        android:id="@+id/view_star"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@id/button"
        ></com.lovebeisaier.StarView>
</RelativeLayout>

效果：

下班