Android实现图片放大缩小

package com.min.Test_Gallery;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Color;import android.graphics.Matrix;import android.os.Bundle;import android.util.DisplayMetrics;import android.util.Log;import android.view.GestureDetector;import android.view.KeyEvent;import android.view.MotionEvent;import android.view.View;import android.view.GestureDetector.OnGestureListener;import android.view.View.OnTouchListener;import android.widget.Button;import android.widget.FrameLayout;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.Toast;public class DisplayImage extends Activity implements OnTouchListener, OnGestureListener {private static final String TAG = "DisplayImage";private static final int FLING_MIN_DISTANCE = 100;private static final int FLING_MIN_VELOCITY = 200;/* 相关变量声明 */private ImageView mImageView;private Button mButton01;private Button mButton02;private FrameLayout layout1;private LinearLayout layoutImage;private Bitmap bmp;private int id=0;private int displayWidth;private int displayHeight;private float scaleWidth=1;private float scaleHeight=1;private GestureDetector mGestureDetector;/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);/* 加载display.xml Layout */setContentView(R.layout.display);/* 取得屏幕分辨率大小 */DisplayMetrics dm=new DisplayMetrics();getWindowManager().getDefaultDisplay().getMetrics(dm);displayWidth=dm.widthPixels;displayHeight=dm.heightPixels; /* 初始化相关变量 */Bundle bundle = this.getIntent().getExtras();Integer imageId = bundle.getInt("imageId");Log.i(TAG, "onCreate, imageId = " + imageId); bmp=BitmapFactory.decodeResource(getResources(), imageId); mImageView = (ImageView)findViewById(R.id.myImageView);mImageView.setImageBitmap(bmp);mImageView.setOnTouchListener(this);mImageView.setLongClickable(true);layout1 = (FrameLayout)findViewById(R.id.layout1);layoutImage = (LinearLayout)findViewById(R.id.layoutImage);mButton01 = (Button)findViewById(R.id.myButton1);mButton02 = (Button)findViewById(R.id.myButton2); /* 缩小按钮onClickListener */mButton01.setOnClickListener(new Button.OnClickListener() {@Overridepublic void onClick(View v) {small(); }});/* 放大按钮onClickListener */mButton02.setOnClickListener(new Button.OnClickListener() {@Override public void onClick(View v) {big();} });} // 用户轻触触摸屏，由1个MotionEvent ACTION_DOWN触发@Overridepublic boolean onDown(MotionEvent e) {// TODO Auto-generated method stub//Toast.makeText(this, "onDown", Toast.LENGTH_SHORT).show(); Log.i(TAG, "onDown...");return false;}/* 用户按下触摸屏、快速移动后松开，由1个MotionEvent ACTION_DOWN, * 多个ACTION_MOVE, 1个ACTION_UP触发 * 参数解释： * e1：第1个ACTION_DOWN MotionEvent * e2：最后一个ACTION_MOVE MotionEvent * velocityX：X轴上的移动速度，像素/秒 * velocityY：Y轴上的移动速度，像素/秒 * 触发条件 ： * X轴的坐标位移大于FLING_MIN_DISTANCE，且移动速度大于FLING_MIN_VELOCITY个像素/秒 * @see android.view.GestureDetector$OnGestureListener#onFling(android.view.MotionEvent, android.view.MotionEvent, float, float) */@Overridepublic boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,float velocityY) {// TODO Auto-generated method stubLog.i(TAG, "onFling...");if (e1.getX() - e2.getX() > FLING_MIN_DISTANCE && Math.abs(velocityX) > FLING_MIN_VELOCITY) { // Fling left Toast.makeText(this, "Fling Left", Toast.LENGTH_SHORT).show(); } else if (e2.getX() - e1.getX() > FLING_MIN_DISTANCE && Math.abs(velocityX) > FLING_MIN_VELOCITY) { // Fling right Toast.makeText(this, "Fling Right", Toast.LENGTH_SHORT).show(); } return false;}// 用户长按触摸屏，由多个MotionEvent ACTION_DOWN触发 @Overridepublic void onLongPress(MotionEvent e) {// TODO Auto-generated method stubLog.i(TAG, "onLongPress...");}// 用户按下触摸屏，并拖动，由1个MotionEvent ACTION_DOWN, 多个ACTION_MOVE触发@Overridepublic boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,float distanceY) {// TODO Auto-generated method stubLog.i(TAG, "onScroll...");return false;}// 用户轻触触摸屏，尚未松开或拖动，由一个1个MotionEvent ACTION_DOWN触发// 注意和onDown()的区别，强调的是没有松开或者拖动的状态@Overridepublic void onShowPress(MotionEvent e) {// TODO Auto-generated method stubLog.i(TAG, "onShowPress...");}// 用户（轻触触摸屏后）松开，由一个1个MotionEvent ACTION_UP触发@Overridepublic boolean onSingleTapUp(MotionEvent e) {// TODO Auto-generated method stubLog.i(TAG, "onSingleTapUp...");return false;}@Overridepublic boolean onTouch(View v, MotionEvent event) {// TODO Auto-generated method stubLog.i(TAG, "onTouch...");// Set button visiblemButton01.setVisibility(View.VISIBLE);mButton02.setVisibility(View.VISIBLE);return mGestureDetector.onTouchEvent(event); }//@Override//public boolean onTouchEvent(MotionEvent event) {//// TODO Auto-generated method stub//super.onTouchEvent(event);////Log.i(TAG, "onTouchEvent");//// Set button visible//mButton01.setVisibility(View.VISIBLE);//mButton02.setVisibility(View.VISIBLE);////return true;//}@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {// TODO Auto-generated method stubsuper.onKeyDown(keyCode, event);Log.i(TAG, "onKeyDown...");// Set button visiblemButton01.setVisibility(View.VISIBLE);mButton02.setVisibility(View.VISIBLE);return true;}/* 图片缩小的method */private void small() {int bmpWidth=bmp.getWidth(); int bmpHeight=bmp.getHeight();Log.i(TAG, "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); if(id==0) {/* 如果是第一次按，就删除原来默认的ImageView */layoutImage.removeView(mImageView);} else {/* 如果不是第一次按，就删除上次放大缩小所产生的ImageView */layoutImage.removeView((ImageView)findViewById(id));} /* 产生新的ImageView，放入reSize的Bitmap对象，再放入Layout中 */id++;ImageView imageView = new ImageView(this);imageView.setId(id);imageView.setImageBitmap(resizeBmp);layoutImage.addView(imageView);Log.i(TAG, "imageView.getWidth() = " + imageView.getWidth()+ ", imageView.getHeight() = " + imageView.getHeight());setContentView(layout1);/* 因为图片放到最大时放大按钮会disable，所以在缩小时把它重设为enable */ mButton02.setEnabled(true);mButton02.setTextColor(Color.MAGENTA);}/* 图片放大的method */private void big() {int bmpWidth=bmp.getWidth();int bmpHeight=bmp.getHeight();Log.i(TAG, "bmpWidth = " + bmpWidth + ", bmpHeight = " + bmpHeight);/* 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);if(id==0) {/* 如果是第一次按，就删除原来设置的ImageView */layoutImage.removeView(mImageView);} else {/* 如果不是第一次按，就删除上次放大缩小所产生的ImageView */ layoutImage.removeView((ImageView)findViewById(id));}/* 产生新的ImageView，放入reSize的Bitmap对象，再放入Layout中 */id++;ImageView imageView = new ImageView(this);imageView.setId(id);imageView.setImageBitmap(resizeBmp);layoutImage.addView(imageView);setContentView(layout1);/* 如果再放大会超过屏幕大小，就把Button disable */if( scaleWidth * scale * bmpWidth > bmpWidth * 3 ||scaleHeight * scale * bmpHeight > bmpWidth * 3 ||scaleWidth * scale * bmpWidth > displayWidth * 5 ||scaleHeight * scale * bmpHeight > displayHeight * 5) {mButton02.setEnabled(false);mButton02.setTextColor(Color.GRAY);} else {mButton02.setEnabled(true);mButton02.setTextColor(Color.MAGENTA);}} }

 

display.xml文件

<?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" > <ScrollView xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_weight="19"android:scrollbars="vertical"android:fadingEdge="vertical"><HorizontalScrollView android:layout_height="fill_parent"android:layout_width="wrap_content"> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="horizontal" android:layout_width="fill_parent" android:layout_height="wrap_content" android:gravity="center" android:id="@+id/layoutImage" > <ImageView android:id="@+id/myImageView" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_weight="19" android:paddingTop="5dip" android:paddingBottom="5dip"/></LinearLayout></HorizontalScrollView ></ScrollView> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" > <Button android:id="@+id/myButton1" android:layout_width="45dip" android:layout_height="30dip" android:layout_alignParentLeft="true" android:gravity="left" style="@style/my_style_button" android:visibility="gone" android:text="缩小"/><Button android:id="@+id/myButton2" android:layout_width="45dip" android:layout_height="30dip" android:layout_alignParentRight="true" android:gravity="right" style="@style/my_style_button" android:visibility="gone" android:text="放大"/> </RelativeLayout></FrameLayout>