新浪微博图片缩放的开发实例

Android开发中有时会用到图片缩放效果，即点击图片时显示缩放按钮，过一会消失。本文就根据新浪微博的图片缩放给大家写一个实例，以供参考。下面直接上代码。

package com.Johnson.image.zoom;     
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();     
  }     
}   

布局文件如下：

    <?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"     
          >     
        </ZoomControls>     
            </RelativeLayout>         
    </FrameLayout>