最近做一个项目类似于QQ空间，做到照片浏览的功能，对于QQ空间中点击图片放大至全屏，感觉效果很赞，于是也做了个类似的效果。如下。
我不知道QQ那个是怎么做的，我的思路如下：
首先，从图片缩略界面跳转到图片详情页面，应该是从一个Activity跳转到另外一个Activity，应该图片详情页面也有很多操作，用View或者Dialog不是很好。所以现在难点就是，如何使得前一个界面的ImageView在另外一个界面做缩放切割动画。
一般缩略界面的ImageView的是如上图所示的正方形的，并且是CENTER_CROP缩放属性的。CENTER_CROP属性会导致ImageView中显示的Bitmap有被切割达到填充的效果。
而详情页面的ImageView一般都是FIT_CENTER的缩放属性。所以要保证这个跳转动画的流畅，要做如下的变化：
1、Bitmap的缩放，因为缩略图和详情图的缩放比例肯定不一样
2、Bitmap位置的平移，因为缩略图的位置是不确定的，我们要使他平移到中间
3、Bitmap的切割，因为CENTER_CROP是切割过得，而FIT_CENTER是没有切割的，那么两幅图显示的内容区域是不同的，所以也要显示区域的平滑变换。
要完成上面的效果，如果单单是指对ImageView做一个动画变换，我觉得是完成不了这个要求的。所以自己重写了ImageView来完成上述的变换。
直接贴上主要的ImageView
package com.roamer.ui.view;
import android.animation.Animator;
import android.animation.PropertyValuesHolder;
import android.animation.ValueAnimator;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.widget.ImageView;
/**
* 2d平滑变化的显示图片的ImageView
* 仅限于用于:从一个ScaleType==CENTER_CROP的ImageView，切换到另一个ScaleType=
* FIT_CENTER的ImageView，或者反之 (当然，得使用同样的图片最好)
*
* @author Dean Tao
*
*/
public class SmoothImageView extends ImageView {
private static final int STATE_NORMAL = 0;
private static final int STATE_TRANSFORM_IN = 1;
private static final int STATE_TRANSFORM_OUT = 2;
private int mOriginalWidth;
private int mOriginalHeight;
private int mOriginalLocationX;
private int mOriginalLocationY;
private int mState = STATE_NORMAL;
private Matrix mSmoothMatrix;
private Bitmap mBitmap;
private boolean mTransformStart = false;
private Transfrom mTransfrom;
private final int mBgColor = 0xFF000000;
private int mBgAlpha = 0;
private Paint mPaint;
public SmoothImageView(Context context) {
super(context);
init();
}
public SmoothImageView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public SmoothImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
private void init() {
mSmoothMatrix = new Matrix();
mPaint=new Paint();
mPaint.setColor(mBgColor);
mPaint.setStyle(Style.FILL);
// setBackgroundColor(mBgColor);
}
public void setOriginalInfo(int width, int height, int locationX, int locationY) {
mOriginalWidth = width;
mOriginalHeight = height;
mOriginalLocationX = locationX;
mOriginalLocationY = locationY;
// 因为是屏幕坐标，所以要转换为该视图内的坐标，因为我所用的该视图是MATCH_PARENT，所以不用定位该视图的位置,如果不是的话，还需要定位视图的位置，然后计算mOriginalLocationX和mOriginalLocationY
mOriginalLocationY = mOriginalLocationY - getStatusBarHeight(getContext());
}
/**
* 获取状态栏高度
*
* @return
*/
public static int getStatusBarHeight(Context context) {
Class<?> c = null;
Object obj = null;
java.lang.reflect.Field field = null;
int x = 0;
int statusBarHeight = 0;
try {
c = Class.forName("com.android.internal.R$dimen");
obj = c.newInstance();
field = c.getField("status_bar_height");
x = Integer.parseInt(field.get(obj).toString());
statusBarHeight = context.getResources().getDimensionPixelSize(x);
return statusBarHeight;
} catch (Exception e) {
e.printStackTrace();
}
return statusBarHeight;
}
/**
* 用于开始进入的方法。 调用此方前，需已经调用过setOriginalInfo
*/
public void transformIn() {
mState = STATE_TRANSFORM_IN;
mTransformStart = true;
invalidate();
}
/**
* 用于开始退出的方法。 调用此方前，需已经调用过setOriginalInfo
*/
public void transformOut() {
mState = STATE_TRANSFORM_OUT;
mTransformStart = true;
invalidate();
}
private class Transfrom {
float startScale;// 图片开始的缩放值
float endScale;// 图片结束的缩放值
float scale;// 属性ValueAnimator计算出来的值
LocationSizeF startRect;// 开始的区域
LocationSizeF endRect;// 结束的区域
LocationSizeF rect;// 属性ValueAnimator计算出来的值
void initStartIn() {
scale = startScale;
try {
rect = (LocationSizeF) startRect.clone();
} catch (CloneNotSupportedException e) {
e.printStackTrace();
}
}
void initStartOut() {
scale = endScale;
try {
rect = (LocationSizeF) endRect.clone();
} catch (CloneNotSupportedException e) {
e.printStackTrace();
}
}
}
/**
* 初始化进入的变量信息
*/
private void initTransform() {
if (getDrawable() == null) {
return;
}
if (mBitmap == null || mBitmap.isRecycled()) {
mBitmap = ((BitmapDrawable) getDrawable()).getBitmap();
}
//防止mTransfrom重复的做同样的初始化
if (mTransfrom != null) {
return;
}
if (getWidth() == 0 || getHeight() == 0) {
return;
}
mTransfrom = new Transfrom();
/** 下面为缩放的计算 */
/* 计算初始的缩放值，初始值因为是CENTR_CROP效果，所以要保证图片的宽和高至少1个能匹配原始的宽和高，另1个大于 */
float xSScale = mOriginalWidth / ((float) mBitmap.getWidth());
float ySScale = mOriginalHeight / ((float) mBitmap.getHeight());
float startScale = xSScale > ySScale ? xSScale : ySScale;
mTransfrom.startScale = startScale;
/* 计算结束时候的缩放值，结束值因为要达到FIT_CENTER效果，所以要保证图片的宽和高至少1个能匹配原始的宽和高，另1个小于 */
float xEScale = getWidth() / ((float) mBitmap.getWidth());
float yEScale = getHeight() / ((float) mBitmap.getHeight());
float endScale = xEScale < yEScale ? xEScale : yEScale;
mTransfrom.endScale = endScale;
/**
* 下面计算Canvas Clip的范围，也就是图片的显示的范围，因为图片是慢慢变大，并且是等比例的，所以这个效果还需要裁减图片显示的区域
* ，而显示区域的变化范围是在原始CENTER_CROP效果的范围区域
* ，到最终的FIT_CENTER的范围之间的，区域我用LocationSizeF更好计算
* ，他就包括左上顶点坐标，和宽高，最后转为Canvas裁减的Rect.
*/
/* 开始区域 */
mTransfrom.startRect = new LocationSizeF();
mTransfrom.startRect.left = mOriginalLocationX;
mTransfrom.startRect.top = mOriginalLocationY;
mTransfrom.startRect.width = mOriginalWidth;
mTransfrom.startRect.height = mOriginalHeight;
/* 结束区域 */
mTransfrom.endRect = new LocationSizeF();
float bitmapEndWidth = mBitmap.getWidth() * mTransfrom.endScale;// 图片最终的宽度
float bitmapEndHeight = mBitmap.getHeight() * mTransfrom.endScale;// 图片最终的宽度
mTransfrom.endRect.left = (getWidth() - bitmapEndWidth) / 2;
mTransfrom.endRect.top = (getHeight() - bitmapEndHeight) / 2;
mTransfrom.endRect.width = bitmapEndWidth;
mTransfrom.endRect.height = bitmapEndHeight;
mTransfrom.rect = new LocationSizeF();
}
private class LocationSizeF implements Cloneable{
float left;
float top;
float width;
float height;
@Override
public String toString() {
return "[left:"+left+" top:"+top+" width:"+width+" height:"+height+"]";
}
@Override
public Object clone() throws CloneNotSupportedException {
// TODO Auto-generated method stub
return super.clone();
}
}
/* 下面实现了CENTER_CROP的功能 的Matrix，在优化的过程中，已经不用了 */
private void getCenterCropMatrix() {
if (getDrawable() == null) {
return;
}
if (mBitmap == null || mBitmap.isRecycled()) {
mBitmap = ((BitmapDrawable) getDrawable()).getBitmap();
}
/* 下面实现了CENTER_CROP的功能 */
float xScale = mOriginalWidth / ((float) mBitmap.getWidth());
float yScale = mOriginalHeight / ((float) mBitmap.getHeight());
float scale = xScale > yScale ? xScale : yScale;
mSmoothMatrix.reset();
mSmoothMatrix.setScale(scale, scale);
mSmoothMatrix.postTranslate(-(scale * mBitmap.getWidth() / 2 - mOriginalWidth / 2), -(scale * mBitmap.getHeight() / 2 - mOriginalHeight / 2));
}
private void getBmpMatrix() {
if (getDrawable() == null) {
return;
}
if (mTransfrom == null) {
return;
}
if (mBitmap == null || mBitmap.isRecycled()) {
mBitmap = ((BitmapDrawable) getDrawable()).getBitmap();
}
/* 下面实现了CENTER_CROP的功能 */
mSmoothMatrix.setScale(mTransfrom.scale, mTransfrom.scale);
mSmoothMatrix.postTranslate(-(mTransfrom.scale * mBitmap.getWidth() / 2 - mTransfrom.rect.width / 2),
-(mTransfrom.scale * mBitmap.getHeight() / 2 - mTransfrom.rect.height / 2));
}
@Override
protected void onDraw(Canvas canvas) {
if (getDrawable() == null) {
return; // couldn‘t resolve the URI
}
if (mState == STATE_TRANSFORM_IN || mState == STATE_TRANSFORM_OUT) {
if (mTransformStart) {
initTransform();
}
if (mTransfrom == null) {
super.onDraw(canvas);
return;
}
if (mTransformStart) {
if (mState == STATE_TRANSFORM_IN) {
mTransfrom.initStartIn();
} else {
mTransfrom.initStartOut();
}
}
if(mTransformStart){
Log.d("Dean", "mTransfrom.startScale:"+mTransfrom.startScale);
Log.d("Dean", "mTransfrom.startScale:"+mTransfrom.endScale);
Log.d("Dean", "mTransfrom.scale:"+mTransfrom.scale);
Log.d("Dean", "mTransfrom.startRect:"+mTransfrom.startRect.toString());
Log.d("Dean", "mTransfrom.endRect:"+mTransfrom.endRect.toString());
Log.d("Dean", "mTransfrom.rect:"+mTransfrom.rect.toString());
}
mPaint.setAlpha(mBgAlpha);
canvas.drawPaint(mPaint);
int saveCount = canvas.getSaveCount();
canvas.save();
// 先得到图片在此刻的图像Matrix矩阵
getBmpMatrix();
canvas.translate(mTransfrom.rect.left, mTransfrom.rect.top);
canvas.clipRect(0, 0, mTransfrom.rect.width, mTransfrom.rect.height);
canvas.concat(mSmoothMatrix);
getDrawable().draw(canvas);
canvas.restoreToCount(saveCount);
if (mTransformStart) {
mTransformStart=false;
startTransform(mState);
}
} else {
//当Transform In变化完成后，把背景改为黑色，使得Activity不透明
mPaint.setAlpha(255);
canvas.drawPaint(mPaint);
super.onDraw(canvas);
}
}
private void startTransform(final int state) {
if (mTransfrom == null) {
return;
}
ValueAnimator valueAnimator = new ValueAnimator();
valueAnimator.setDuration(300);
valueAnimator.setInterpolator(new AccelerateDecelerateInterpolator());
if (state == STATE_TRANSFORM_IN) {
PropertyValuesHolder scaleHolder = PropertyValuesHolder.ofFloat("scale", mTransfrom.startScale, mTransfrom.endScale);
PropertyValuesHolder leftHolder = PropertyValuesHolder.ofFloat("left", mTransfrom.startRect.left, mTransfrom.endRect.left);
PropertyValuesHolder topHolder = PropertyValuesHolder.ofFloat("top", mTransfrom.startRect.top, mTransfrom.endRect.top);
PropertyValuesHolder widthHolder = PropertyValuesHolder.ofFloat("width", mTransfrom.startRect.width, mTransfrom.endRect.width);
PropertyValuesHolder heightHolder = PropertyValuesHolder.ofFloat("height", mTransfrom.startRect.height, mTransfrom.endRect.height);
PropertyValuesHolder alphaHolder = PropertyValuesHolder.ofInt("alpha", 0, 255);
valueAnimator.setValues(scaleHolder, leftHolder, topHolder, widthHolder, heightHolder, alphaHolder);
} else {
PropertyValuesHolder scaleHolder = PropertyValuesHolder.ofFloat("scale", mTransfrom.endScale, mTransfrom.startScale);
PropertyValuesHolder leftHolder = PropertyValuesHolder.ofFloat("left", mTransfrom.endRect.left, mTransfrom.startRect.left);
PropertyValuesHolder topHolder = PropertyValuesHolder.ofFloat("top", mTransfrom.endRect.top, mTransfrom.startRect.top);
PropertyValuesHolder widthHolder = PropertyValuesHolder.ofFloat("width", mTransfrom.endRect.width, mTransfrom.startRect.width);
PropertyValuesHolder heightHolder = PropertyValuesHolder.ofFloat("height", mTransfrom.endRect.height, mTransfrom.startRect.height);
PropertyValuesHolder alphaHolder = PropertyValuesHolder.ofInt("alpha", 255, 0);
valueAnimator.setValues(scaleHolder, leftHolder, topHolder, widthHolder, heightHolder, alphaHolder);
}
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public synchronized void onAnimationUpdate(ValueAnimator animation) {
mTransfrom.scale = (Float) animation.getAnimatedValue("scale");
mTransfrom.rect.left = (Float) animation.getAnimatedValue("left");
mTransfrom.rect.top = (Float) animation.getAnimatedValue("top");
mTransfrom.rect.width = (Float) animation.getAnimatedValue("width");
mTransfrom.rect.height = (Float) animation.getAnimatedValue("height");
mBgAlpha = (Integer) animation.getAnimatedValue("alpha");
invalidate();
((Activity)getContext()).getWindow().getDecorView().invalidate();
}
});
valueAnimator.addListener(new ValueAnimator.AnimatorListener() {
@Override
public void onAnimationStart(Animator animation) {
}
@Override
public void onAnimationRepeat(Animator animation) {
}
@Override
public void onAnimationEnd(Animator animation) {
/*
* 如果是进入的话，当然是希望最后停留在center_crop的区域。但是如果是out的话，就不应该是center_crop的位置了
* ， 而应该是最后变化的位置，因为当out的时候结束时，不回复视图是Normal，要不然会有一个突然闪动回去的bug
*/
// TODO 这个可以根据实际需求来修改
if (state == STATE_TRANSFORM_IN) {
mState = STATE_NORMAL;
}
if (mTransformListener != null) {
mTransformListener.onTransformComplete(state);
}
}
@Override
public void onAnimationCancel(Animator animation) {
}
});
valueAnimator.start();
}
public void setOnTransformListener(TransformListener listener) {
mTransformListener = listener;
}
private TransformListener mTransformListener;
public static interface TransformListener {
/**
*
* @param mode
* STATE_TRANSFORM_IN 1 ,STATE_TRANSFORM_OUT 2
*/
void onTransformComplete(int mode);// mode 1
}
}
使用的时候，从前一个Activity传递到详情Activity下面几个主要的信息：
Intent intent = new Intent(MainActivity.this, SpaceImageDetailActivity.class);
intent.putExtra("images", (ArrayList<String>) datas);//非必须
intent.putExtra("position", position);
int[] location = new int[2];
imageView.getLocationOnScreen(location);
intent.putExtra("locationX", location[0]);//必须
intent.putExtra("locationY", location[1]);//必须
intent.putExtra("width", imageView.getWidth());//必须
intent.putExtra("height", imageView.getHeight());//必须
startActivity(intent);
overridePendingTransition(0, 0);
在详情Activity接受到这些参数，并对SmoothImageView初始化位置信息，然后就可以进行变化了。
mDatas = (ArrayList<String>) getIntent().getSerializableExtra("images");
mPosition = getIntent().getIntExtra("position", 0);
mLocationX = getIntent().getIntExtra("locationX", 0);
mLocationY = getIntent().getIntExtra("locationY", 0);
mWidth = getIntent().getIntExtra("width", 0);
mHeight = getIntent().getIntExtra("height", 0);
imageView = new SmoothImageView(this);
imageView.setOriginalInfo(mWidth, mHeight, mLocationX, mLocationY);
imageView.transformIn();
imageView.setLayoutParams(new ViewGroup.LayoutParams(-1, -1));
imageView.setScaleType(ScaleType.FIT_CENTER);
setContentView(imageView);
ImageLoader.getInstance().displayImage(mDatas.get(mPosition), imageView);
上面的就已经完成了图片的缩放效果，但是还需要设置下Activity透明的风格，才能使得alpha效果体验出来，用户体验更好。
对Activity设置如下风格，另外说明，在SmoothImageView中没有定位视图的位置，只是做了对状态栏的处理，所以要设置Activity 为NotitleBar，具体style如下：
<style name="IMTheme.Transparent" >
<item name="android:windowBackground">@android:color/transparent</item>
<item name="android:windowIsTranslucent">true</item>
<item name="android:windowNoTitle">true</item>
<item name="android:windowContentOverlay">@null</item>
</style>