Android浏览图片，点击放大至全屏效果

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+" 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<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接受到这些參数，并对SmoothImageView初始化位置信息，然后就能够进行变化了。

		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：

 <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>

Demo下载