how to rotate an image continuously?

问题:

I am trying to rotate this image by using a thread. what should I do?

     public class Start extends Activity {
        View base;
            Bitmap rotate, base1, rotate1;
        ImageView rotator;
        float angle, pivX, pivY;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.start);
            base = findViewById(R.id.base);
            rotator = (ImageView) findViewById(R.id.rotator);
            pivX = (rotator.getLeft()) / 2;
            pivY = (rotator.getTop()) / 2;
            Thread thread = new Thread() {
        @Override
        public void run() {
            for (angle = 0; angle < 50; angle++) {
                Matrix matrix = new Matrix();
                rotator.setScaleType(ScaleType.MATRIX); // required
                matrix.postRotate((float) angle, pivX, pivY);
                rotator.setImageMatrix(matrix);
                if (angle == 40) {`enter code here`
                    angle = 0;
                    return;
                }
            }
        }
    };

    thread.start();

        }
    }

回答1:

use this code for rotating a button

btn_rotate = (Button)findViewById(R.id.btn_rotate);
rotation = AnimationUtils.loadAnimation(MainActivity.this, R.anim.rotate);
rotation.setFillAfter(true);
btn_rotate.startAnimation(rotation);

rotate.xml

put this file in res->anim->rotate.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android" >

<rotate
    android:duration="500"
    android:fromDegrees="0"
    android:pivotX="50%"
    android:pivotY="50%"
    android:repeatCount="infinite"
    android:startOffset="0"
    android:toDegrees="360" />
</set>

回答2:

Check this out ..

Your Java class ..

package com.example.rotate;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.animation.Animation.AnimationListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity implements AnimationListener {

    TextView txtMessage;
    Button btnStart;

    // Animation
    Animation animFadein;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        txtMessage = (TextView) findViewById(R.id.tv);
        btnStart = (Button) findViewById(R.id.btn);

        // load the animation
        animFadein = AnimationUtils.loadAnimation(getApplicationContext(),
                R.anim.rotate);

        // set animation listener
        animFadein.setAnimationListener(this);

        // button click event
        btnStart.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                txtMessage.setVisibility(View.VISIBLE);

                // start the animation
                txtMessage.startAnimation(animFadein);
            }
        });

    }

    @Override
    public void onAnimationEnd(Animation animation) {
        // Take any action after completing the animation

        // check for fade in animation
        if (animation == animFadein) {
            Toast.makeText(getApplicationContext(), "Animation Stopped",
                    Toast.LENGTH_SHORT).show();
        }

    }

    @Override
    public void onAnimationRepeat(Animation animation) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onAnimationStart(Animation animation) {
        // TODO Auto-generated method stub

    }

}

your xml file ..

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >


    <Button 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/btn"
        />

    <TextView
        android:id="@+id/tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="@string/hello_world" />

</RelativeLayout>

And one more thing .. you need to define anim folder in your res folder.

now place rotate.xml file in anim folder.

rotate.xml file

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <rotate android:fromDegrees="0"
        android:toDegrees="360"
        android:pivotX="50%"
        android:pivotY="50%"
        android:duration="600"
        android:repeatMode="restart"
        android:repeatCount="infinite"
        android:interpolator="@android:anim/cycle_interpolator"/>

</set>

That's it. you are good to go.

回答3:

I know it's probably late but here's how I do a rotate animation on java code:

RotateAnimation rotate = new RotateAnimation(
                0, 360,
                Animation.RELATIVE_TO_SELF, 0.5f,
                Animation.RELATIVE_TO_SELF, 0.5f
        );

rotate.setDuration(900);
rotate.setRepeatCount(Animation.INFINITE);
itemImage.startAnimation(rotate);

回答4:

In Kotlin:

 ivBall.setOnClickListener(View.OnClickListener {

            //Animate using XML
            // val rotateAnimation = AnimationUtils.loadAnimation(activity, R.anim.rotate_indefinitely)

            //OR using Code
            val rotateAnimation = RotateAnimation(
                    0f, 359f,
                    Animation.RELATIVE_TO_SELF, 0.5f,
                    Animation.RELATIVE_TO_SELF, 0.5f

            )
            rotateAnimation.duration = 300
            rotateAnimation.repeatCount = 2

            //Either way you can add Listener like this
            rotateAnimation.setAnimationListener(object : Animation.AnimationListener {

                override fun onAnimationStart(animation: Animation?) {
                }

                override fun onAnimationRepeat(animation: Animation?) {
                }

                override fun onAnimationEnd(animation: Animation?) {

                    val rand = Random()
                    val ballHit = rand.nextInt(50) + 1
                    Toast.makeText(context, "ballHit : " + ballHit, Toast.LENGTH_SHORT).show()
                }
            })

            ivBall.startAnimation(rotateAnimation)
        })

rotate_indefinitely.xml

<?xml version="1.0" encoding="UTF-8"?>
<rotate xmlns:android="http://schemas.android.com/apk/res/android"
    android:duration="600"
    android:fromDegrees="0"
    android:interpolator="@android:anim/linear_interpolator"
    android:pivotX="50%"
    android:pivotY="50%"
    android:repeatCount="infinite"
    android:toDegrees="360" />