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. */

@Override

public 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() {

@Override

public 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

@Override

public 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)

*/

@Override

public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,

float velocityY) {

// TODO Auto-generated method stub

Log.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

@Override

public void onLongPress(MotionEvent e) {

// TODO Auto-generated method stub

Log.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

@Override

public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,

float distanceY) {

// TODO Auto-generated method stub

Log.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

@Override

public void onShowPress(MotionEvent e) {

// TODO Auto-generated method stub

Log.i(TAG, "onShowPress...");

}

// 用户（轻触触摸屏后）松开，由一个1个MotionEvent ACTION_UP触发

@Override

public boolean onSingleTapUp(MotionEvent e) {

// TODO Auto-generated method stub

Log.i(TAG, "onSingleTapUp...");

return false;

}

@Override

public boolean onTouch(View v, MotionEvent event) {

// TODO Auto-generated method stub

Log.i(TAG, "onTouch...");

// Set button visible

mButton01.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;

// }

@Override

public boolean onKeyDown(int keyCode, KeyEvent event) {

// TODO Auto-generated method stub

super.onKeyDown(keyCode, event);

Log.i(TAG, "onKeyDown...");

// Set button visible

mButton01.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

[xhtml] view plaincopy

<?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>