自定义动画，高级动画的实现
package com.example.administrator.myanimation4;
import android.animation.ValueAnimator;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
我们知道颜色都是由ARGB组成，A表示alpha透明度，R表示red红色，G表示green绿色，B表示blue蓝色。在动画中，颜色的变化从R-G-B。
package com.example.administrator.myanimation4;
import android.animation.TypeEvaluator;
/** * Created by hd on 2015/12/19. */
/**实现颜色变化的动画接口 */
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;
//抽取开始颜色和结束颜色的rgb的值
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);
//初始化颜色，仅执行一次
if(mCurrentRed == -1){
mCurrentRed = startRed;
}
if(mCurrentGreen == -1){
mCurrentGreen = startGreen;
}
if(mCurrentBlue == -1){
mCurrentBlue = startBlue;
}
//取出开始颜色与结束颜色之间rgb的绝对值，也就是色差
int redDiff = Math.abs(startRed - endRed);
int greenDiff = Math.abs(startGreen - endGreen);
int blueDiff = Math.abs(startBlue - endBlue);
//总色差
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);
}
String currentColor = "#" + getHexString(mCurrentRed) + getHexString(mCurrentGreen) + getHexString(mCurrentBlue);
return currentColor;
}
//计算接下去要变化的颜色
private int getCurrentColor(int startColor, int endColor, int colorDiff, int offset, float fraction) {
int currentColor;
//如果开始颜色的值大于结束颜色的值，也就是从深变浅
if (startColor > endColor) {
currentColor = (int) (startColor - (fraction * colorDiff - offset));
if(currentColor<endColor){
currentColor = endColor;
}
}else {
//如果开始颜色的值小于结束颜色的值，也就是从浅变深
currentColor = (int) (startColor + (fraction * colorDiff - offset));
if(currentColor>endColor){
currentColor = endColor;
}
}
return currentColor;
}
//把十进制转成十六进制
private String getHexString(int Value){
String hexString = Integer.toHexString(Value);
if(hexString.length() == 1){
hexString = "0" +hexString;
}
return hexString;
}
}
package com.example.administrator.myanimation4;
/** * Created by hd on 2015/12/19. */
//点的位置
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 void setX(float x) {
this.x = x;
}
public float getY() {
return y;
}
public void setY(float y) {
this.y = y;
}
}
package com.example.administrator.myanimation4;
import android.animation.TypeEvaluator;
import android.util.Log;
/** * Created by hd on 2015/12/19. */
// 点移动，形成移动的动画
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);
Log.i("hhhd", "fraction is " + fraction);
return point;
}
}
package com.example.administrator.myanimation4;
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;
/** * Created by hd on 2015/12/19. */
public class PointView extends View {
private Paint mPaint;
private Point currentPoint;
public static final float RADIUS = 50f;
public PointView(Context context, AttributeSet attrs) {
super(context, attrs);
//初始化画笔
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setColor(Color.RED);
}
@Override
protected void onDraw(Canvas canvas) {
if(currentPoint == null){
currentPoint = new Point(RADIUS, RADIUS);
drawView(canvas);
startAnimation();
}else {
drawView(canvas);
}
}
private void startAnimation() {
Point startPoint = new Point(RADIUS, RADIUS);
Point endPoint = new Point(getWidth() - RADIUS, getHeight() - RADIUS);
ValueAnimator animator = ValueAnimator.ofObject(new PointEvaluator(), startPoint, endPoint);
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
currentPoint = (Point) animation.getAnimatedValue();
invalidate();
}
});
ObjectAnimator animator2 = ObjectAnimator.ofObject(this, "color", new ColorEvaluator(), "#0000FF", "#FF0000");
AnimatorSet animatorSet = new AnimatorSet();
animatorSet.play(animator).with(animator2);
animatorSet.setDuration(5 * 1000);
animatorSet.start();
}
private void drawView(Canvas canvas) {
float x = currentPoint.getX();
float y = currentPoint.getY();
canvas.drawCircle(x, y, RADIUS, mPaint);
}
private String color;
public String getColor() {
return color;
}
public void setColor(String color) {
this.color = color;
mPaint.setColor(Color.parseColor(color));
invalidate();
}
}
<?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">
<com.example.administrator.myanimation4.PointView android:layout_width="match_parent" android:layout_height="match_parent" />
</RelativeLayout>