Android ValueAnimator和ObjectAnimator的高級用法（代碼實現）

參考文章：http://blog.csdn.net/guolin_blog/article/details/43816093

一、ValueAnimator的高級用法

1.MainActivity.java

public class MainActivity extends  Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        //兩個Point對象，現在需要將Point1通過動畫平滑過度到Point2
        Point point1 = new Point(0, 0);  
        Point point2 = new Point(300, 300);  
        ValueAnimator anim = ValueAnimator.ofObject(new PointEvaluator(), point1, point2);  
        anim.setDuration(5000);  
        anim.start();  
    }
   
}

2.MyAnimView.java

public class MyAnimView extends View {  
	  
    public static final float RADIUS = 50f;  
  
    private Point currentPoint;  
  
    private Paint mPaint;  
  
    public MyAnimView(Context context, AttributeSet attrs) {  
        super(context, attrs);  
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);  
        mPaint.setColor(Color.BLUE);  
    }  
  
    @Override  
    protected void onDraw(Canvas canvas) {  
        if (currentPoint == null) {  
            currentPoint = new Point(RADIUS, RADIUS);  
            drawCircle(canvas);  
            startAnimation();  
        } else {  
            drawCircle(canvas);  
        }  
    }  
  
    private void drawCircle(Canvas canvas) {  
        float x = currentPoint.getX();  
        float y = currentPoint.getY();  
        canvas.drawCircle(x, y, RADIUS, mPaint);  
    }  
  
    private void startAnimation() {  
        Point startPoint = new Point(RADIUS, RADIUS);  
        Point endPoint = new Point(getWidth() - RADIUS, getHeight() - RADIUS);  
        ValueAnimator anim = ValueAnimator.ofObject(new PointEvaluator(), startPoint, endPoint);  
        anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {  
            @Override  
            public void onAnimationUpdate(ValueAnimator animation) {  
                currentPoint = (Point) animation.getAnimatedValue();  
                invalidate();  
            }  
        });  
        anim.setDuration(5000);  
        anim.start();  
    }  
  
} 

3.Point.java

public class Point {  
	  
    private float x;  
    private float y;  
  
    public Point(float x, float y) {  
        this.x = x;  
        this.y = y;  
    }  
  
    public float getX() {  
        return x;  
    }  
  
    public float getY() {  
        return y;  
    }  
}  

4.PointEvaluator.java

public class PointEvaluator implements TypeEvaluator{  
	  
    @Override  
    public Object evaluate(float fraction, Object startValue, Object endValue) {  
        Point startPoint = (Point) startValue;  
        Point endPoint = (Point) endValue;  
        float x = startPoint.getX() + fraction * (endPoint.getX() - startPoint.getX());  
        float y = startPoint.getY() + fraction * (endPoint.getY() - startPoint.getY());  
        Point point = new Point(x, y);  
        return point;  
    }  
  
}  

5.佈局文件：activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    >  
  
    <com.th.animationtest2.MyAnimView  
        android:layout_width="match_parent"  
        android:layout_height="match_parent" />  
  
</RelativeLayout>  

二、ObjectAnimator的高級用法

1.MainActivity.java

public class MainActivity extends Activity {
	
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        //兩個Point對象，現在需要將Point1通過動畫平滑過度到Point2
        Point point1 = new Point(0, 0);  
        Point point2 = new Point(300, 300);  
        ValueAnimator anim = ValueAnimator.ofObject(new PointEvaluator(), point1, point2);  
        anim.setDuration(5000);  
        anim.start();  
    }

}

2.Point.java

public class Point {  
	  
    private float x;  
    private float y;  
  
    public Point(float x, float y) {  
        this.x = x;  
        this.y = y;  
    }  
  
    public float getX() {  
        return x;  
    }  
  
    public float getY() {  
        return y;  
    }  
}  

3.MyAnimView.java

import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

public class MyAnimView extends View {  
	  
    public static final float RADIUS = 50f;  
  
    private Point currentPoint;  
  
    private Paint mPaint;  
  
    public MyAnimView(Context context, AttributeSet attrs) {  
        super(context, attrs);  
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);  
        mPaint.setColor(Color.BLUE);  
    }  
  
    @Override  
    protected void onDraw(Canvas canvas) {  
        if (currentPoint == null) {  
            currentPoint = new Point(RADIUS, RADIUS);  
            drawCircle(canvas);  
            startAnimation();  
        } else {  
            drawCircle(canvas);  
        }  
    }  
  
    private void drawCircle(Canvas canvas) {  
        float x = currentPoint.getX();  
        float y = currentPoint.getY();  
        canvas.drawCircle(x, y, RADIUS, mPaint);  
    }  
  
    /*private void startAnimation() {  
        Point startPoint = new Point(RADIUS, RADIUS);  
        Point endPoint = new Point(getWidth() - RADIUS, getHeight() - RADIUS);  
        ValueAnimator anim = ValueAnimator.ofObject(new PointEvaluator(), startPoint, endPoint);  
        anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {  
            @Override  
            public void onAnimationUpdate(ValueAnimator animation) {  
                currentPoint = (Point) animation.getAnimatedValue();  
                invalidate();  
            }  
        });  
        anim.setDuration(5000);  
        anim.start();  
    }  */
    
    private void startAnimation() {  
        Point startPoint = new Point(RADIUS, RADIUS);  
        Point endPoint = new Point(getWidth() - RADIUS, getHeight() - RADIUS);  
        ValueAnimator anim = ValueAnimator.ofObject(new PointEvaluator(), startPoint, endPoint);  
        anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {  
            @Override  
            public void onAnimationUpdate(ValueAnimator animation) {  
                currentPoint = (Point) animation.getAnimatedValue();  
                invalidate();  
            }  
        });  
        
        //從藍色到紅色的動畫過度，歷時5秒
        ObjectAnimator anim2 = ObjectAnimator.ofObject(this, "color", new ColorEvaluator(),   
                "#0000FF", "#FF0000");  
        AnimatorSet animSet = new AnimatorSet();  
        animSet.play(anim).with(anim2);  
        animSet.setDuration(5000);  
        animSet.start();  
    }  
  
    private String color;  
    
    public String getColor() {  
        return color;  
    }  
  
    public void setColor(String color) {  
        this.color = color;  
        mPaint.setColor(Color.parseColor(color));  
        invalidate();  
    }  
}  

4.PointEvaluator.java

public class PointEvaluator implements TypeEvaluator{  
	  
    @Override  
    public Object evaluate(float fraction, Object startValue, Object endValue) {  
        Point startPoint = (Point) startValue;  
        Point endPoint = (Point) endValue;  
        float x = startPoint.getX() + fraction * (endPoint.getX() - startPoint.getX());  
        float y = startPoint.getY() + fraction * (endPoint.getY() - startPoint.getY());  
        Point point = new Point(x, y);  
        return point;  
    }  
  
}  

5.ColorEvaluator.java

public class ColorEvaluator implements TypeEvaluator {  
	  
    private int mCurrentRed = -1;  
  
    private int mCurrentGreen = -1;  
  
    private int mCurrentBlue = -1;  
  
    @Override  
    public Object evaluate(float fraction, Object startValue, Object endValue) {  
        String startColor = (String) startValue;  
        String endColor = (String) endValue;  
        int startRed = Integer.parseInt(startColor.substring(1, 3), 16);  
        int startGreen = Integer.parseInt(startColor.substring(3, 5), 16);  
        int startBlue = Integer.parseInt(startColor.substring(5, 7), 16);  
        int endRed = Integer.parseInt(endColor.substring(1, 3), 16);  
        int endGreen = Integer.parseInt(endColor.substring(3, 5), 16);  
        int endBlue = Integer.parseInt(endColor.substring(5, 7), 16);  
        // 初始化顏色的值  
        if (mCurrentRed == -1) {  
            mCurrentRed = startRed;  
        }  
        if (mCurrentGreen == -1) {  
            mCurrentGreen = startGreen;  
        }  
        if (mCurrentBlue == -1) {  
            mCurrentBlue = startBlue;  
        }  
        // 計算初始顏色和結束顏色之間的差值  
        int redDiff = Math.abs(startRed - endRed);  
        int greenDiff = Math.abs(startGreen - endGreen);  
        int blueDiff = Math.abs(startBlue - endBlue);  
        int colorDiff = redDiff + greenDiff + blueDiff;  
        if (mCurrentRed != endRed) {  
            mCurrentRed = getCurrentColor(startRed, endRed, colorDiff, 0,  
                    fraction);  
        } else if (mCurrentGreen != endGreen) {  
            mCurrentGreen = getCurrentColor(startGreen, endGreen, colorDiff,  
                    redDiff, fraction);  
        } else if (mCurrentBlue != endBlue) {  
            mCurrentBlue = getCurrentColor(startBlue, endBlue, colorDiff,  
                    redDiff + greenDiff, fraction);  
        }  
        // 將計算出的當前顏色的值組裝返回  
        String currentColor = "#" + getHexString(mCurrentRed)  
                + getHexString(mCurrentGreen) + getHexString(mCurrentBlue);  
        return currentColor;  
    }  
  
    /** 
     * 根據fraction值來計算當前的顏色。 
     */  
    private int getCurrentColor(int startColor, int endColor, int colorDiff,  
            int offset, float fraction) {  
        int currentColor;  
        if (startColor > endColor) {  
            currentColor = (int) (startColor - (fraction * colorDiff - offset));  
            if (currentColor < endColor) {  
                currentColor = endColor;  
            }  
        } else {  
            currentColor = (int) (startColor + (fraction * colorDiff - offset));  
            if (currentColor > endColor) {  
                currentColor = endColor;  
            }  
        }  
        return currentColor;  
    }  
      
    /** 
     * 將10進制顏色值轉換成16進制。 
     */  
    private String getHexString(int value) {  
        String hexString = Integer.toHexString(value);  
        if (hexString.length() == 1) {  
            hexString = "0" + hexString;  
        }  
        return hexString;  
    }  
  
}  

6.佈局文件：activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    >  
  
    <com.th.objectanimatortest.MyAnimView  
        android:layout_width="match_parent"  
        android:layout_height="match_parent" />  
  
</RelativeLayout>