图片简单放大

先上效果图：
[img]

[/img]

布局文件：
main.xm

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
	xmlns:android="http://schemas.android.com/apk/res/android"
	android:orientation="vertical"
	android:layout_width="fill_parent"
	android:layout_height="fill_parent"
	android:id="@+id/layout1">

	<RelativeLayout
		xmlns:android="http://schemas.android.com/apk/res/android"
		android:layout_width="fill_parent"
		android:layout_height="fill_parent"
		android:id="@+id/rl">

		<ScrollView
			xmlns:android="http://schemas.android.com/apk/res/android"
			android:layout_width="fill_parent"
			android:layout_height="fill_parent"
			android:layout_weight="19"
			android:scrollbars="none"
			android:fadingEdge="vertical"
			android:layout_gravity="center"
			android:gravity="center">

			<HorizontalScrollView
				android:layout_height="fill_parent"
				android:layout_width="fill_parent"
				android:scrollbars="none"
				android:layout_gravity="center"
				android:gravity="center"
				android:id="@+id/hs">
				<LinearLayout
					android:orientation="horizontal"
					android:layout_width="fill_parent"
					android:layout_height="fill_parent"
					android:id="@+id/layoutImage"
					android:layout_gravity="center"
					android:gravity="center">
					<ImageView
						android:layout_gravity="center"
						android:gravity="center"
						android:id="@+id/myImageView"
						android:layout_width="fill_parent"
						android:layout_height="fill_parent"
						android:layout_weight="19"
						android:paddingTop="5dip"
						android:paddingBottom="5dip" />
				</LinearLayout>
			</HorizontalScrollView>
		</ScrollView>



		<ZoomControls
			android:id="@+id/zoomcontrol"
			android:layout_width="wrap_content"
			android:layout_height="wrap_content"
			android:layout_centerHorizontal="true"
			android:layout_alignParentBottom="true" />

	</RelativeLayout>

</FrameLayout>  

MainActivity:

package com.magus.img;

import android.app.Activity;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.content.DialogInterface.OnKeyListener;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.os.Bundle;
import android.os.Handler;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.ZoomControls;

public class MainActivity extends Activity {
    /** Called when the activity is first created. */
	


	private final int LOADING_IMAGE = 1;
	public static String KEY_IMAGEURI = "ImageUri";
	private ZoomControls zoom;
	private ImageView mImageView;
	private LinearLayout layoutImage;
	private int displayWidth;
	private int displayHeight;
	/**图片资源*/
	private Bitmap bmp;
	/**宽的缩放比例*/
	private float scaleWidth = 1;
	/**高的缩放比例*/
	private float scaleHeight = 1;
	/**用来计数放大+1  缩小-1*/
	private int  zoomNumber=0;
	/**点击屏幕显示缩放按钮，三秒消失*/
	private int showTime=3000;

	
	RelativeLayout rl;
	Handler mHandler = new Handler();
	private Runnable task = new Runnable() {
		public void run() {
			
			zoom.setVisibility(View.INVISIBLE);
			
		}
	};
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
		//showDialog(LOADING_IMAGE);
		//图片是从网络上获取的话，需要加入滚动条
		  bmp=BitmapFactory.decodeResource(getResources(), R.drawable.image);
		//removeDialog(LOADING_IMAGE);
	    initZoom();
}
    
    
	@Override
	protected Dialog onCreateDialog(int id) {
		switch (id) {
		case LOADING_IMAGE: {
			final ProgressDialog dialog = new ProgressDialog(this);
			dialog.setOnKeyListener(new OnKeyListener() {
				@Override
				public boolean onKey(DialogInterface dialog, int keyCode,
						KeyEvent event) {
					if (keyCode == KeyEvent.KEYCODE_BACK) {
						finish();
					}
					return false;
				}
			});
			dialog.setMessage("正在加载图片请稍后...");
			dialog.setIndeterminate(true);
			dialog.setCancelable(true);
			return dialog;
		}
		}
		return null;
	}
	
	
	public void initZoom() {

		/* 取得屏幕分辨率大小 */
		DisplayMetrics dm = new DisplayMetrics();
		getWindowManager().getDefaultDisplay().getMetrics(dm);
		displayWidth = dm.widthPixels;
		displayHeight = dm.heightPixels;
		mImageView = (ImageView) findViewById(R.id.myImageView);
		mImageView.setImageBitmap(bmp);
		layoutImage = (LinearLayout) findViewById(R.id.layoutImage);
		mImageView.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
                /**
                 * 在图片上和整个view上同时添加点击监听捕捉屏幕
                 * 点击事件，来显示放大缩小按钮 
                 * */			
				zoom.setVisibility(View.VISIBLE);
				mHandler.removeCallbacks(task);
				mHandler.postDelayed(task, showTime);
			}
		});
		
		layoutImage.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
			
				zoom.setVisibility(View.VISIBLE);
				mHandler.removeCallbacks(task);
				mHandler.postDelayed(task, showTime);
			}
		});
		
		zoom = (ZoomControls) findViewById(R.id.zoomcontrol);
		zoom.setIsZoomInEnabled(true);
		zoom.setIsZoomOutEnabled(true);
		// 图片放大
		zoom.setOnZoomInClickListener(new OnClickListener() {
			public void onClick(View v) {
				big();
			}
		});
		// 图片减小
		zoom.setOnZoomOutClickListener(new OnClickListener() {

			public void onClick(View v) {
				small();
			}

		});
		
		
		
		zoom.setVisibility(View.VISIBLE);
		mHandler.postDelayed(task, showTime);

	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		// TODO Auto-generated method stub
	    /**
         * 在图片上和整个view上同时添加点击监听捕捉屏幕
         * 点击事件，来显示放大缩小按钮 
         * */		
		zoom.setVisibility(View.VISIBLE);
		mHandler.removeCallbacks(task);
		mHandler.postDelayed(task, showTime);
		return false;
	}

	@Override
	public boolean onKeyDown(int keyCode, KeyEvent event) {
		// TODO Auto-generated method stub
		super.onKeyDown(keyCode, event);

		return true;
	}

	/* 图片缩小的method */
	private void small() {
		
	
		
		--zoomNumber;
		int bmpWidth = bmp.getWidth();
		int bmpHeight = bmp.getHeight();

		Log.i("","bmpWidth = " + bmpWidth + ", bmpHeight = " + bmpHeight);

		/* 设置图片缩小的比例 */
		double scale = 0.8;
		/* 计算出这次要缩小的比例 */
		scaleWidth = (float) (scaleWidth * scale);
		scaleHeight = (float) (scaleHeight * scale);
		/* 产生reSize后的Bitmap对象 */
		Matrix matrix = new Matrix();
		matrix.postScale(scaleWidth, scaleHeight);
		Bitmap resizeBmp = Bitmap.createBitmap(bmp, 0, 0, bmpWidth, bmpHeight,
				matrix, true);
		mImageView.setImageBitmap(resizeBmp);

		/* 限制缩小尺寸 */
		if ((scaleWidth * scale * bmpWidth < bmpWidth / 4
				|| scaleHeight * scale * bmpHeight > bmpWidth /4
				|| scaleWidth * scale * bmpWidth > displayWidth / 5
				|| scaleHeight * scale * bmpHeight > displayHeight / 5)&&(zoomNumber==-1) ){
			
		zoom.setIsZoomOutEnabled(false);
		
		} else {
			
		zoom.setIsZoomOutEnabled(true);
	
		}
		
		zoom.setIsZoomInEnabled(true);
		System.gc();
	}

	/* 图片放大的method */
	private void big() {
		++zoomNumber;
		int bmpWidth = bmp.getWidth();
		int bmpHeight = bmp.getHeight();

		/* 设置图片放大的比例 */
		double scale = 1.25;
		/* 计算这次要放大的比例 */
		scaleWidth = (float) (scaleWidth * scale);
		scaleHeight = (float) (scaleHeight * scale);
		/* 产生reSize后的Bitmap对象 */
		Matrix matrix = new Matrix();
		matrix.postScale(scaleWidth, scaleHeight);
		Bitmap resizeBmp = Bitmap.createBitmap(bmp, 0, 0, bmpWidth, bmpHeight,
				matrix, true);
		mImageView.setImageBitmap(resizeBmp);
		/* 限制放大尺寸 */
		if (scaleWidth * scale * bmpWidth > bmpWidth * 4
				|| scaleHeight * scale * bmpHeight > bmpWidth * 4
				|| scaleWidth * scale * bmpWidth > displayWidth * 5
				|| scaleHeight * scale * bmpHeight > displayHeight * 5) {
			
			zoom.setIsZoomInEnabled(false);
		
		} else {
			
			zoom.setIsZoomInEnabled(true);
	
		}
	
		zoom.setIsZoomOutEnabled(true);
		
	System.gc();
	}
	
}