安卓 单指移动，双指缩放，双击放大缩小的 iamgeview

本博客基于<a target=_blank href="http://blog.csdn.net/cf125313/article/details/47977059"> 安卓 单指移动，双指缩放的 iamgeview</a>进行的扩展

代码如下

package com.wellav.dolphin.media.ui;import android.content.Context;import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.Matrix;import android.graphics.PointF;import android.util.AttributeSet;import android.util.FloatMath;import android.util.Log;import android.view.GestureDetector;import android.view.GestureDetector.OnDoubleTapListener;import android.view.GestureDetector.SimpleOnGestureListener;import android.view.MotionEvent;import android.widget.ImageView;public class ZoomImageView extends ImageView {	private Matrix matrix = new Matrix();	private Matrix savedMatrix = new Matrix();	private static final int NONE = 0;	private static final int DRAG = 1;	private static final int ZOOM = 2;	private int mode = NONE;	private static final float MAX_SCALE = 3;	private static float mCurScale = 1.0f;	private static float mStartScale;	// 第一个按下的手指的点	private PointF startPoint = new PointF();	// 两个按下的手指的触摸点的中点	private PointF midPoint = new PointF();	// 初始的两个手指按下的触摸点的距离	private float oriDis = 1f;	public ZoomImageView(Context context, AttributeSet attrs) {		super(context, attrs);		// mGestureDetector=new GestureDetector(context, new GestureListener());	}	private int count = 0;	@Override	protected void onDraw(Canvas canvas) {		// TODO Auto-generated method stub		super.onDraw(canvas);		if (count == 0) {			float[] values = new float[9];			getImageMatrix().getValues(values);			mStartScale = values[Matrix.MSCALE_X];			Log.e("", "s=" + mStartScale);			count++;		}	}	private float isZoomChanged() {		float[] values = new float[9];		getImageMatrix().getValues(values);		float scale = values[Matrix.MSCALE_X];		if (scale != mStartScale)			return mStartScale / scale;		else			return 2.0f;		// return scale!=1.0f;	}	@Override	public void setImageBitmap(Bitmap bm) {		// TODO Auto-generated method stub		super.setImageBitmap(bm);	}	private long startTime = 0;	@Override	public boolean onTouchEvent(MotionEvent event) {		// 进行与操作是为了判断多点触摸		switch (event.getAction() & MotionEvent.ACTION_MASK) {		case MotionEvent.ACTION_DOWN:			// 第一个手指按下事件			setScaleType(ScaleType.MATRIX);			long interval = event.getEventTime() - startTime;			Log.e("", "now-st=" + interval + "st=" + startTime);			if (interval < 300) {				Log.e("", "double click");				matrix.set(getImageMatrix());				float scale = isZoomChanged();				Log.e("", "scale=" + scale);				matrix.postScale(scale, scale, getWidth() / 2, getHeight() / 2);				setImageMatrix(matrix);				break;			}			startTime = event.getEventTime();			Log.e("", "down");			Log.e("", "width=" + getDrawable().getBounds().width());			matrix.set(getImageMatrix());			savedMatrix.set(matrix);			startPoint.set(event.getX(), event.getY());			mode = DRAG;			break;		case MotionEvent.ACTION_POINTER_DOWN:			// 第二个手指按下事件						Log.e("", "double down");			oriDis = distance(event);			if (oriDis > 10f) {				savedMatrix.set(matrix);				midPoint = middle(event);				mode = ZOOM;			}			break;		case MotionEvent.ACTION_UP:			// 手指放开事件			mode = NONE;			break;		case MotionEvent.ACTION_POINTER_UP:			// 手指放开事件			mode = NONE;			break;		case MotionEvent.ACTION_MOVE:			// 手指滑动事件			if (mode == DRAG) {				// 是一个手指拖动								matrix.set(savedMatrix);				Log.e("mmm", "event.getX() - startPoint.x＝" + event.getX()						+ "-" + startPoint.x);				Log.e("mmm", matrix.toString());				matrix.postTranslate(event.getX() - startPoint.x, event.getY()						- startPoint.y);				Log.e("mmm", "x=" + getX() + "y=" + getY());			} else if (mode == ZOOM) {				// 两个手指滑动				float newDist = distance(event);				if (newDist > 10f) {					matrix.set(savedMatrix);					float scale = newDist / oriDis;					float[] values = new float[9];					matrix.getValues(values);					scale = checkMaxScale(scale, values);				}			}			break;		}		// 设置ImageView的Matrix		this.setImageMatrix(matrix);		return true;	}	/**	 * 检验scale，使图像缩放后不会超出最大倍数	 * 	 * @param scale	 * @param values	 * @return	 */	private float checkMaxScale(float scale, float[] values) {		if (scale * values[Matrix.MSCALE_X] > MAX_SCALE)			scale = MAX_SCALE / values[Matrix.MSCALE_X];		else if (scale * values[Matrix.MSCALE_X] < mStartScale)			scale = mStartScale / values[Matrix.MSCALE_X];		matrix.postScale(scale, scale, getWidth() / 2, getHeight() / 2);		return scale;	}	// 计算两个触摸点之间的距离	private float distance(MotionEvent event) {		float x = event.getX(0) - event.getX(1);		float y = event.getY(0) - event.getY(1);		return FloatMath.sqrt(x * x + y * y);	}	// 计算两个触摸点的中点	private PointF middle(MotionEvent event) {		float x = event.getX(0) + event.getX(1);		float y = event.getY(0) + event.getY(1);		return new PointF(x / 2, y / 2);	}}