在android中以圆形路径移动图像

Question

我有一个图像,我想在onClick()没有动画的按钮的圆形路径事件中移动它,

我不知道怎么做..有什么帮助？

---

这是我的主要课程

public class MainActivity extends Activity {
MyAnimation animation;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    animation =new MyAnimation ();

}

我正在使用你给出的代码

public class MyAnimation extends Animation {
float cx,cy,prevX,prevY,r;

@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
    super.applyTransformation(interpolatedTime, t);

    float angle = (float) (interpolatedTime * 2 * Math.PI);
    // r = radius, cx and cy = center point, a = angle (radians)
    float x = (float) (cx + r * Math.cos(angle)) ; 
    float y = (float) (cy + r * Math.sin(angle));

    float dx = prevX - x;
    float dy = prevY - y;

    prevX = x;
    prevY = y;

    t.getMatrix().setTranslate(dx, dy);
}

}

这是我想要以圆形移动的xml图像.

<ImageView
    android:id="@+id/myanimation"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:src="@drawable/ic_launcher" />

Answer 1

我认为你有两个选择:要么你创建一个自定义动画,要么你创建你的ImageView,然后使用一个表面自己沿着路径绘制它.

第一个选项更容易,并且可能会给出更好的结果,因为在动画类中,时间是由你处理的Interpolators(线性时间,快速启动,结束正常等).我强烈建议你编写自定义动画,因为我不明白为什么你不想使用Animation类(动画图像正是你想要的).

编辑:我花了一些时间并实现了以下内容.它并不是一尘不染,而是以圆形路径为图像制作动画.

活动:

public class MainActivity extends Activity {

    private ImageView image;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        image = (ImageView) findViewById(R.id.image);

        image.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Animation anim = new MyAnimation(image, 100);
                anim.setDuration(3000);
                image.startAnimation(anim);
            }
        });
    }

}

动画类:

public class MyAnimation extends Animation {

    private View view;
    private float cx, cy;           // center x,y position of circular path
    private float prevX, prevY;     // previous x,y position of image during animation
    private float r;                // radius of circle
    private float prevDx, prevDy;


    /**
     * @param view - View that will be animated
     * @param r - radius of circular path
     */
    public MyAnimation(View view, float r){
        this.view = view;
        this.r = r;
    }

    @Override
    public boolean willChangeBounds() {
        return true;
    }

    @Override
    public void initialize(int width, int height, int parentWidth, int parentHeight) {
        // calculate position of image center
        int cxImage = width / 2;
        int cyImage = height / 2;
        cx = view.getLeft() + cxImage;
        cy = view.getTop() + cyImage;

        // set previous position to center
        prevX = cx;
        prevY = cy;
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        if(interpolatedTime == 0){
            t.getMatrix().setTranslate(prevDx, prevDy);
            return;
        }

        float angleDeg = (interpolatedTime * 360f + 90) % 360;
        float angleRad = (float) Math.toRadians(angleDeg);

        // r = radius, cx and cy = center point, a = angle (radians)
        float x = (float) (cx + r * Math.cos(angleRad));
        float y = (float) (cy + r * Math.sin(angleRad));


        float dx = prevX - x;
        float dy = prevY - y;

        prevX = x;
        prevY = y;

        prevDx = dx;
        prevDy = dy;


        t.getMatrix().setTranslate(dx, dy);
    }
}

XML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">

    <ImageView
        android:id="@+id/image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:src="@drawable/ic_launcher" />

</RelativeLayout>

你可能需要在这里和那里调整它以获得你想要的东西,但这可以作为基础.