近期做一个项目类似于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，感觉效果非常赞，于是也做了个类似的效果。

例如以下。

我不知道QQ那个是怎么做的。我的思路例如以下：

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非常多操作。用View或者Dialog不是非常好。所以如今难点就是。怎样使得前一个界面的ImageView在另外一个界面做缩放分割动画。

一般缩略界面的ImageView的是如上图所看到的的正方形的，而且是CENTER_CROP缩放属性的。CENTER_CROP属性会导致ImageView中显示的Bitmap有被分割达到填充的效果。

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。要做例如以下的变化：

1、Bitmap的缩放，由于缩略图和详情图的缩放比例肯定不一样

2、Bitmap位置的平移。由于缩略图的位置是不确定的，我们要使他平移到中间

3、Bitmap的分割，由于CENTER_CROP是分割过得，而FIT_CENTER是没有分割的，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。

要完毕上面的效果，假设单单是指对ImageView做一个动画变换，我认为是完毕不了这个要求的。所以自己重写了ImageView来完毕上述的变换。

直接贴上基本的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，切换到还有一个ScaleType=

* FIT_CENTER的ImageView，或者反之 (当然，得使用相同的图片最好)

*

* @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;

// 由于是屏幕坐标。所以要转换为该视图内的坐标，由于我所用的该视图是MATCH_PARENT，所以不用定位该视图的位置,假设不是的话。还须要定位视图的位置，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;

}

/**

* 用于開始进入的方法。 调用此方前。需已经调用过setOriginalInfo

*/

public void transformIn() {

mState = STATE_TRANSFORM_IN;

mTransformStart = true;

invalidate();

}

/**

* 用于開始退出的方法。

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;// 图片開始的缩放值

float endScale;// 图片结束的缩放值

float scale;// 属性ValueAnimator计算出来的值

LocationSizeF startRect;// 開始的区域

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反复的做相同的初始化

if (mTransfrom != null) {

return;

}

if (getWidth() == 0 || getHeight() == 0) {

return;

}

mTransfrom = new Transfrom();

/** 以下为缩放的计算 */

/* 计算初始的缩放值。初始值由于是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。结束值由于要达到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;

/**

* 以下计算Canvas Clip的范围，也就是图片的显示的范围，由于图片是慢慢变大，而且是等比例的。所以这个效果还须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

* ，到终于的FIT_CENTER的范围之间的，区域我用LocationSizeF更好计算

* ，他就包含左上顶点坐标。和宽高，最后转为Canvas裁减的Rect.

*/

/* 開始区域 */

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;// 图片终于的宽度

float bitmapEndHeight = mBitmap.getHeight() * mTransfrom.endScale;// 图片终于的宽度

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();

}

}

/* 以下实现了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();

}

/* 以下实现了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();

}

/* 以下实现了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变化完毕后，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) {

/*

* 假设是进入的话，当然是希望最后停留在center_crop的区域。可是假设是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。由于当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 这个能够依据实际需求来改动

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以下几个基本的信息：

Intent intent = new Intent(MainActivity.this, SpaceImageDetailActivity.class);

intent.putExtra("images", (ArrayList) 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接受到这些參数，并对SmoothImageView初始化位置信息，然后就能够进行变化了。

mDatas = (ArrayList) 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);

上面的就已经完毕了图片的缩放效果，可是还须要设置下Activity透明的风格。才干使得alpha效果体验出来，用户体验更好。

对Activity设置例如以下风格。另外说明，在SmoothImageView中没有定位视图的位置。仅仅是做了对状态栏的处理。所以要设置Activity 为NotitleBar，详细style例如以下：

@android:color/transparent

true

true

@null