ViewPager圖片預覽之圖片的放大縮小，移動，切換

終極版

package com.zhy.view;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Matrix;
import android.graphics.RectF;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.ScaleGestureDetector.OnScaleGestureListener;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.ViewTreeObserver;
import android.widget.ImageView;
/**
 * 
 * @author zhy
 * 博客地址：http://blog.csdn.net/lmj623565791
 */
public class ZoomImageView extends ImageView implements OnScaleGestureListener,
		OnTouchListener, ViewTreeObserver.OnGlobalLayoutListener

{
	private static final String TAG = ZoomImageView.class.getSimpleName();
	public static final float SCALE_MAX = 4.0f;
	private static final float SCALE_MID = 2.0f;

	/**
	 * 初始化時的縮放比例，如果圖片寬或高大於屏幕，此值將小於0
	 */
	private float initScale = 1.0f;
	private boolean once = true;

	/**
	 * 用於存放矩陣的9個值
	 */
	private final float[] matrixValues = new float[9];

	/**
	 * 縮放的手勢檢測
	 */
	private ScaleGestureDetector mScaleGestureDetector = null;
	private final Matrix mScaleMatrix = new Matrix();

	/**
	 * 用於雙擊檢測
	 */
	private GestureDetector mGestureDetector;
	private boolean isAutoScale;

	private int mTouchSlop;

	private float mLastX;
	private float mLastY;

	private boolean isCanDrag;
	private int lastPointerCount;

	private boolean isCheckTopAndBottom = true;
	private boolean isCheckLeftAndRight = true;

	public ZoomImageView(Context context)
	{
		this(context, null);
	}

	public ZoomImageView(Context context, AttributeSet attrs)
	{
		super(context, attrs);
		super.setScaleType(ScaleType.MATRIX);
		mGestureDetector = new GestureDetector(context,
				new SimpleOnGestureListener()
				{
					@Override
					public boolean onDoubleTap(MotionEvent e)
					{
						if (isAutoScale == true)
							return true;

						float x = e.getX();
						float y = e.getY();
						Log.e("DoubleTap", getScale() + " , " + initScale);
						if (getScale() < SCALE_MID)
						{
							ZoomImageView.this.postDelayed(
									new AutoScaleRunnable(SCALE_MID, x, y), 16);
							isAutoScale = true;
						} else if (getScale() >= SCALE_MID
								&& getScale() < SCALE_MAX)
						{
							ZoomImageView.this.postDelayed(
									new AutoScaleRunnable(SCALE_MAX, x, y), 16);
							isAutoScale = true;
						} else
						{
							ZoomImageView.this.postDelayed(
									new AutoScaleRunnable(initScale, x, y), 16);
							isAutoScale = true;
						}

						return true;
					}
				});
		mScaleGestureDetector = new ScaleGestureDetector(context, this);
		this.setOnTouchListener(this);
	}

	/**
	 * 自動縮放的任務
	 * 
	 * @author zhy
	 * 
	 */
	private class AutoScaleRunnable implements Runnable
	{
		static final float BIGGER = 1.07f;
		static final float SMALLER = 0.93f;
		private float mTargetScale;
		private float tmpScale;

		/**
		 * 縮放的中心
		 */
		private float x;
		private float y;

		/**
		 * 傳入目標縮放值，根據目標值與當前值，判斷應該放大還是縮小
		 * 
		 * @param targetScale
		 */
		public AutoScaleRunnable(float targetScale, float x, float y)
		{
			this.mTargetScale = targetScale;
			this.x = x;
			this.y = y;
			if (getScale() < mTargetScale)
			{
				tmpScale = BIGGER;
			} else
			{
				tmpScale = SMALLER;
			}

		}

		@Override
		public void run()
		{
			// 進行縮放
			mScaleMatrix.postScale(tmpScale, tmpScale, x, y);
			checkBorderAndCenterWhenScale();
			setImageMatrix(mScaleMatrix);

			final float currentScale = getScale();
			// 如果值在合法范圍內，繼續縮放
			if (((tmpScale > 1f) && (currentScale < mTargetScale))
					|| ((tmpScale < 1f) && (mTargetScale < currentScale)))
			{
				ZoomImageView.this.postDelayed(this, 16);
			} else
			// 設置為目標的縮放比例
			{
				final float deltaScale = mTargetScale / currentScale;
				mScaleMatrix.postScale(deltaScale, deltaScale, x, y);
				checkBorderAndCenterWhenScale();
				setImageMatrix(mScaleMatrix);
				isAutoScale = false;
			}

		}
	}

	@SuppressLint("NewApi")
	@Override
	public boolean onScale(ScaleGestureDetector detector)
	{
		float scale = getScale();
		float scaleFactor = detector.getScaleFactor();

		if (getDrawable() == null)
			return true;

		/**
		 * 縮放的范圍控制
		 */
		if ((scale < SCALE_MAX && scaleFactor > 1.0f)
				|| (scale > initScale && scaleFactor < 1.0f))
		{
			/**
			 * 最大值最小值判斷
			 */
			if (scaleFactor * scale < initScale)
			{
				scaleFactor = initScale / scale;
			}
			if (scaleFactor * scale > SCALE_MAX)
			{
				scaleFactor = SCALE_MAX / scale;
			}
			/**
			 * 設置縮放比例
			 */
			mScaleMatrix.postScale(scaleFactor, scaleFactor,
					detector.getFocusX(), detector.getFocusY());
			checkBorderAndCenterWhenScale();
			setImageMatrix(mScaleMatrix);
		}
		return true;

	}

	/**
	 * 在縮放時，進行圖片顯示范圍的控制
	 */
	private void checkBorderAndCenterWhenScale()
	{

		RectF rect = getMatrixRectF();
		float deltaX = 0;
		float deltaY = 0;

		int width = getWidth();
		int height = getHeight();

		// 如果寬或高大於屏幕，則控制范圍
		if (rect.width() >= width)
		{
			if (rect.left > 0)
			{
				deltaX = -rect.left;
			}
			if (rect.right < width)
			{
				deltaX = width - rect.right;
			}
		}
		if (rect.height() >= height)
		{
			if (rect.top > 0)
			{
				deltaY = -rect.top;
			}
			if (rect.bottom < height)
			{
				deltaY = height - rect.bottom;
			}
		}
		// 如果寬或高小於屏幕，則讓其居中
		if (rect.width() < width)
		{
			deltaX = width * 0.5f - rect.right + 0.5f * rect.width();
		}
		if (rect.height() < height)
		{
			deltaY = height * 0.5f - rect.bottom + 0.5f * rect.height();
		}
		Log.e(TAG, "deltaX = " + deltaX + " , deltaY = " + deltaY);

		mScaleMatrix.postTranslate(deltaX, deltaY);

	}

	/**
	 * 根據當前圖片的Matrix獲得圖片的范圍
	 * 
	 * @return
	 */
	private RectF getMatrixRectF()
	{
		Matrix matrix = mScaleMatrix;
		RectF rect = new RectF();
		Drawable d = getDrawable();
		if (null != d)
		{
			rect.set(0, 0, d.getIntrinsicWidth(), d.getIntrinsicHeight());
			matrix.mapRect(rect);
		}
		return rect;
	}

	@Override
	public boolean onScaleBegin(ScaleGestureDetector detector)
	{
		return true;
	}

	@Override
	public void onScaleEnd(ScaleGestureDetector detector)
	{
	}

	@Override
	public boolean onTouch(View v, MotionEvent event)
	{

		if (mGestureDetector.onTouchEvent(event))
			return true;
		mScaleGestureDetector.onTouchEvent(event);

		float x = 0, y = 0;
		// 拿到觸摸點的個數
		final int pointerCount = event.getPointerCount();
		// 得到多個觸摸點的x與y均值
		for (int i = 0; i < pointerCount; i++)
		{
			x += event.getX(i);
			y += event.getY(i);
		}
		x = x / pointerCount;
		y = y / pointerCount;

		/**
		 * 每當觸摸點發生變化時，重置mLasX , mLastY
		 */
		if (pointerCount != lastPointerCount)
		{
			isCanDrag = false;
			mLastX = x;
			mLastY = y;
		}

		lastPointerCount = pointerCount;
		RectF rectF = getMatrixRectF();
		switch (event.getAction())
		{
		case MotionEvent.ACTION_DOWN:
			if (rectF.width() > getWidth() || rectF.height() > getHeight())
			{
				getParent().requestDisallowInterceptTouchEvent(true);
			}
			break;
		case MotionEvent.ACTION_MOVE:
			if (rectF.width() > getWidth() || rectF.height() > getHeight())
			{
				getParent().requestDisallowInterceptTouchEvent(true);
			}
			Log.e(TAG, "ACTION_MOVE");
			float dx = x - mLastX;
			float dy = y - mLastY;

			if (!isCanDrag)
			{
				isCanDrag = isCanDrag(dx, dy);
			}
			if (isCanDrag)
			{

				if (getDrawable() != null)
				{
					// if (getMatrixRectF().left == 0 && dx > 0)
					// {
					// getParent().requestDisallowInterceptTouchEvent(false);
					// }
					//
					// if (getMatrixRectF().right == getWidth() && dx < 0)
					// {
					// getParent().requestDisallowInterceptTouchEvent(false);
					// }
					isCheckLeftAndRight = isCheckTopAndBottom = true;
					// 如果寬度小於屏幕寬度，則禁止左右移動
					if (rectF.width() < getWidth())
					{
						dx = 0;
						isCheckLeftAndRight = false;
					}
					// 如果高度小雨屏幕高度，則禁止上下移動
					if (rectF.height() < getHeight())
					{
						dy = 0;
						isCheckTopAndBottom = false;
					}
					

					mScaleMatrix.postTranslate(dx, dy);
					checkMatrixBounds();
					setImageMatrix(mScaleMatrix);
				}
			}
			mLastX = x;
			mLastY = y;
			break;

		case MotionEvent.ACTION_UP:
		case MotionEvent.ACTION_CANCEL:
			Log.e(TAG, "ACTION_UP");
			lastPointerCount = 0;
			break;
		}

		return true;
	}

	/**
	 * 獲得當前的縮放比例
	 * 
	 * @return
	 */
	public final float getScale()
	{
		mScaleMatrix.getValues(matrixValues);
		return matrixValues[Matrix.MSCALE_X];
	}

	@Override
	protected void onAttachedToWindow()
	{
		super.onAttachedToWindow();
		getViewTreeObserver().addOnGlobalLayoutListener(this);
	}

	@SuppressWarnings("deprecation")
	@Override
	protected void onDetachedFromWindow()
	{
		super.onDetachedFromWindow();
		getViewTreeObserver().removeGlobalOnLayoutListener(this);
	}

	@Override
	public void onGlobalLayout()
	{
		if (once)
		{
			Drawable d = getDrawable();
			if (d == null)
				return;
			Log.e(TAG, d.getIntrinsicWidth() + " , " + d.getIntrinsicHeight());
			int width = getWidth();
			int height = getHeight();
			// 拿到圖片的寬和高
			int dw = d.getIntrinsicWidth();
			int dh = d.getIntrinsicHeight();
			float scale = 1.0f;
			// 如果圖片的寬或者高大於屏幕，則縮放至屏幕的寬或者高
			if (dw > width && dh <= height)
			{
				scale = width * 1.0f / dw;
			}
			if (dh > height && dw <= width)
			{
				scale = height * 1.0f / dh;
			}
			// 如果寬和高都大於屏幕，則讓其按按比例適應屏幕大小
			if (dw > width && dh > height)
			{
				scale = Math.min(width * 1.0f / dw, height * 1.0f / dh);
			}
			initScale = scale;

			Log.e(TAG, "initScale = " + initScale);
			mScaleMatrix.postTranslate((width - dw) / 2, (height - dh) / 2);
			mScaleMatrix.postScale(scale, scale, getWidth() / 2,
					getHeight() / 2);
			// 圖片移動至屏幕中心
			setImageMatrix(mScaleMatrix);
			once = false;
		}

	}

	/**
	 * 移動時，進行邊界判斷，主要判斷寬或高大於屏幕的
	 */
	private void checkMatrixBounds()
	{
		RectF rect = getMatrixRectF();

		float deltaX = 0, deltaY = 0;
		final float viewWidth = getWidth();
		final float viewHeight = getHeight();
		// 判斷移動或縮放後，圖片顯示是否超出屏幕邊界
		if (rect.top > 0 && isCheckTopAndBottom)
		{
			deltaY = -rect.top;
		}
		if (rect.bottom < viewHeight && isCheckTopAndBottom)
		{
			deltaY = viewHeight - rect.bottom;
		}
		if (rect.left > 0 && isCheckLeftAndRight)
		{
			deltaX = -rect.left;
		}
		if (rect.right < viewWidth && isCheckLeftAndRight)
		{
			deltaX = viewWidth - rect.right;
		}
		mScaleMatrix.postTranslate(deltaX, deltaY);
	}

	/**
	 * 是否是推動行為
	 * 
	 * @param dx
	 * @param dy
	 * @return
	 */
	private boolean isCanDrag(float dx, float dy)
	{
		return Math.sqrt((dx * dx) + (dy * dy)) >= mTouchSlop;
	}

}

布局文件：activity_main.xml

在activity中使用：

package com.zhy.zhy_scalegesturedetector02;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

import com.zhy.view.ZoomImageView;

public class MainActivity extends Activity
{
	private ViewPager mViewPager;
	private int[] mImgs = new int[] { R.drawable.tbug, R.drawable.a,
			R.drawable.xx };
	private ImageView[] mImageViews = new ImageView[mImgs.length];

	@Override
	protected void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		setContentView(R.layout.vp);
		
		mViewPager = (ViewPager) findViewById(R.id.id_viewpager);
		mViewPager.setAdapter(new PagerAdapter()
		{

			@Override
			public Object instantiateItem(ViewGroup container, int position)
			{
				ZoomImageView imageView = new ZoomImageView(
						getApplicationContext());
				imageView.setImageResource(mImgs[position]);
				container.addView(imageView);
				mImageViews[position] = imageView;
				return imageView;
			}

			@Override
			public void destroyItem(ViewGroup container, int position,
					Object object)
			{
				container.removeView(mImageViews[position]);
			}

			@Override
			public boolean isViewFromObject(View arg0, Object arg1)
			{
				return arg0 == arg1;
			}

			@Override
			public int getCount()
			{
				return mImgs.length;
			}
		});

	}
}