Android - RotateAnimation - fromDegrees toDegrees变量

Question

我是Android的新手，我有一个小问题。我找到了RotateAnimation的代码：

存储RotateAnimation所有数据的xml文件：

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
    android:interpolator="@android:anim/linear_interpolator">
    <rotate
        android:fromDegrees="0"
        android:toDegrees="360"
        android:pivotX="50%"
        android:pivotY="50%"
        android:duration="20000"
        android:startOffset="0"/>
</set>

java文件：

package com.example.helloword;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.NavUtils;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.Button;
import android.widget.ImageView;

public class Rotation_test extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_rotation_test);
//        getActionBar().setDisplayHomeAsUpEnabled(true);


        Button buttonRotateCenter = (Button) findViewById(R.id.rotatecenter);
        final ImageView floatingImage = (ImageView) findViewById(R.id.floatingimage);


        final Animation animationRotateCenter = AnimationUtils.loadAnimation(
                this, R.anim.rotate_center);
        buttonRotateCenter.setOnClickListener(new Button.OnClickListener() {

            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                floatingImage.startAnimation(animationRotateCenter);
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_rotation_test, menu);
        return true;
    }


    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                NavUtils.navigateUpFromSameTask(this);
                return true;
        }
        return super.onOptionsItemSelected(item);
    }

}

如何在xml文件中创建这两个值的变量？

    android:fromDegrees="0"
    android:toDegrees="360"

Answer 1

根据RotateAnimation类参考(http://developer.android.com/reference/android/view/animation/RotateAnimation.html)，该类不为fromDegrees和toDegrees提供setter方法。因此，如果需要在代码中设置这些值，则必须在代码中创建RotateAnimation对象，并将fromDegrees和toDegrees值传递给构造函数。

RotateAnimation rotateAnimation = new RotateAnimation(fromDegrees, toDegrees);

Answer 2

尝试以下代码，它可能会起作用：

       <?xml version="1.0" encoding="utf-8"?>
        <rotate
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:fromDegrees="45"
        android:toDegrees="45"
        android:pivotX="50%"
        android:pivotY="50%"
        android:duration="0"
        android:startOffset="0"
        />

主代码：

  Animation rotation = AnimationUtils.loadAnimation(this, R.anim.rotation);
    myView.startAnimation(rotation);

Answer 3

试试另一个：

     Matrix matrix=new Matrix();
 imageView.setScaleType(ScaleType.MATRIX);   //required
 matrix.postRotate((float) angle, pivX, pivY);
 imagView.setImageMatrix(matrix);