android-安卓图片的缩放，以及下载保存如本地。

上一篇文章介绍了怎么把图片保存到指定的文件夹目录下。今天就来说说如何实现图片的缩放。

 很明显我们需要一个工具类：直接上代码吧！

DragImageView.java

package cn.guyu.util;

import com.example.fragmenttabhost.R;
import com.guyu.fragmenttabhost.HahItemActivity;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.os.AsyncTask;
import android.text.method.MovementMethod;
import android.util.AttributeSet;
import android.util.FloatMath;
import android.util.Log;
import android.view.MotionEvent;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.Animation;
import android.view.animation.Animation.AnimationListener;
import android.view.animation.ScaleAnimation;
import android.widget.ImageView;

/****
 * 这里你要明白几个方法执行的流程： 首先ImageView是继承自View的子类.
 * onLayout方法：是一个回调方法.该方法会在在View中的layout方法中执行，在执行layout方法前面会首先执行setFrame方法.
 * layout方法：
 * setFrame方法：判断我们的View是否发生变化，如果发生变化，那么将最新的l，t，r，b传递给View，然后刷新进行动态更新UI.
 * 并且返回ture.没有变化返回false.
 * 
 * invalidate方法：用于刷新当前控件,
 * 
 * 
 */
public class DragImageView extends ImageView {

	private Activity mActivity;

	private int screen_W, screen_H;// 可见屏幕的宽高度

	private int bitmap_W, bitmap_H;// 当前图片宽高

	private int MAX_W, MAX_H, MIN_W, MIN_H;// 极限值

	private int current_Top, current_Right, current_Bottom, current_Left;// 当前图片上下左右坐标

	private int start_Top = -1, start_Right = -1, start_Bottom = -1,
			start_Left = -1;// 初始化默认位置.

	private int start_x, start_y, current_x, current_y;// 触摸位置

	private float beforeLenght, afterLenght;// 两触点距离

	private float scale_temp;// 缩放比例

	/**
	 * 模式 NONE：无 DRAG：拖拽. ZOOM:缩放
	 * 
	
	 * 
	 */
	private enum MODE {
		NONE, DRAG, ZOOM

	};

	private MODE mode = MODE.NONE;// 默认模式

	private boolean isControl_V = false;// 垂直监控

	private boolean isControl_H = false;// 水平监控

	private ScaleAnimation scaleAnimation;// 缩放动画

	private boolean isScaleAnim = false;// 缩放动画

	private MyAsyncTask myAsyncTask;// 异步动画

	/** 构造方法 **/
	public DragImageView(Context context) {
		super(context);
	}

	public void setmActivity(Activity mActivity) {
		this.mActivity = mActivity;
	//findViewById(R.id.haha_back_bt);
	}

	/** 可见屏幕宽度 **/
	public void setScreen_W(int screen_W) {
		this.screen_W = screen_W;
	}

	/** 可见屏幕高度 **/
	public void setScreen_H(int screen_H) {
		this.screen_H = screen_H;
	}

	public DragImageView(Context context, AttributeSet attrs) {
		super(context, attrs);
	}

	/***
	 * 设置显示图片
	 */
	@Override
	public void setImageBitmap(Bitmap bm) {
		super.setImageBitmap(bm);
		/** 获取图片宽高 **/
		bitmap_W = bm.getWidth();
		bitmap_H = bm.getHeight();

		MAX_W = bitmap_W * 3;
		MAX_H = bitmap_H * 3;

		MIN_W = bitmap_W / 2;
		MIN_H = bitmap_H / 2;

	}

	@Override
	protected void onLayout(boolean changed, int left, int top, int right,
			int bottom) {
		super.onLayout(changed, left, top, right, bottom);
		if (start_Top == -1) {
			start_Top = top;
			start_Left = left;
			start_Bottom = bottom;
			start_Right = right;
		}

	}

	/***
	 * touch 事件
	 */
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		/** 处理单点、多点触摸 **/
		switch (event.getAction() & MotionEvent.ACTION_MASK) {
		case MotionEvent.ACTION_DOWN:
			onTouchDown(event);
			
			break;
		// 多点触摸
		case MotionEvent.ACTION_POINTER_DOWN:
			onPointerDown(event);
			break;

		case MotionEvent.ACTION_MOVE:
			onTouchMove(event);
			break;
		case MotionEvent.ACTION_UP:
			mode = MODE.NONE;
			break;

		// 多点松开
		case MotionEvent.ACTION_POINTER_UP:
			mode = MODE.NONE;
			/** 执行缩放还原 **/
			if (isScaleAnim) {
				doScaleAnim();
			}
			break;
		}

		return true;
	}

	/** 按下 **/
	void onTouchDown(MotionEvent event) {
		mode = MODE.DRAG;

		current_x = (int) event.getRawX();
		current_y = (int) event.getRawY();

		start_x = (int) event.getX();
		start_y = current_y - this.getTop();
		
	}

	/** 两个手指 只能放大缩小 **/
	void onPointerDown(MotionEvent event) {
		if (event.getPointerCount() == 2) {
			mode = MODE.ZOOM;
			beforeLenght = getDistance(event);// 获取两点的距离
		}
	}

	/** 移动的处理 **/
	void onTouchMove(MotionEvent event) {
		int left = 0, top = 0, right = 0, bottom = 0;
		/** 处理拖动 **/
		if (mode == MODE.DRAG) {

			/** 在这里要进行判断处理，防止在drag时候越界 **/

			/** 获取相应的l，t,r ,b **/
			left = current_x - start_x;
			right = current_x + this.getWidth() - start_x;
			top = current_y - start_y;
			bottom = current_y - start_y + this.getHeight();

			/** 水平进行判断 **/
			if (isControl_H) {
				if (left >= 0) {
					left = 0;
					right = this.getWidth();
				}
				if (right <= screen_W) {
					left = screen_W - this.getWidth();
					right = screen_W;
				}
			} else {
				left = this.getLeft();
				right = this.getRight();
			}
			/** 垂直判断 **/
			if (isControl_V) {
				if (top >= 0) {
					top = 0;
					bottom = this.getHeight();
				}

				if (bottom <= screen_H) {
					top = screen_H - this.getHeight();
					bottom = screen_H;
				}
			} else {
				top = this.getTop();
				bottom = this.getBottom();
			}
			if (isControl_H || isControl_V)
				this.setPosition(left, top, right, bottom);

			current_x = (int) event.getRawX();
			current_y = (int) event.getRawY();

		}
		/** 处理缩放 **/
		else if (mode == MODE.ZOOM) {

			afterLenght = getDistance(event);// 获取两点的距离

			float gapLenght = afterLenght - beforeLenght;// 变化的长度

			if (Math.abs(gapLenght) > 5f) {
				scale_temp = afterLenght / beforeLenght;// 求的缩放的比例

				this.setScale(scale_temp);

				beforeLenght = afterLenght;
			}
		}

	}

	/** 获取两点的距离 **/
	float getDistance(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);
	}

	/** 实现处理拖动 **/
	private void setPosition(int left, int top, int right, int bottom) {
		this.layout(left, top, right, bottom);
	}

	/** 处理缩放 **/
	void setScale(float scale) {
		int disX = (int) (this.getWidth() * Math.abs(1 - scale)) / 4;// 获取缩放水平距离
		int disY = (int) (this.getHeight() * Math.abs(1 - scale)) / 4;// 获取缩放垂直距离

		// 放大
		if (scale > 1 && this.getWidth() <= MAX_W) {
			current_Left = this.getLeft() - disX;
			current_Top = this.getTop() - disY;
			current_Right = this.getRight() + disX;
			current_Bottom = this.getBottom() + disY;

			this.setFrame(current_Left, current_Top, current_Right,
					current_Bottom);
			/***
			 * 此时因为考虑到对称，所以只做一遍判断就可以了。
			 */
			if (current_Top <= 0 && current_Bottom >= screen_H) {
		//		Log.e("jj", "屏幕高度=" + this.getHeight());
				isControl_V = true;// 开启垂直监控
			} else {
				isControl_V = false;
			}
			if (current_Left <= 0 && current_Right >= screen_W) {
				isControl_H = true;// 开启水平监控
			} else {
				isControl_H = false;
			}

		}
		// 缩小
		else if (scale < 1 && this.getWidth() >= MIN_W) {
			current_Left = this.getLeft() + disX;
			current_Top = this.getTop() + disY;
			current_Right = this.getRight() - disX;
			current_Bottom = this.getBottom() - disY;
			/***
			 * 在这里要进行缩放处理
			 */
			// 上边越界
			if (isControl_V && current_Top > 0) {
				current_Top = 0;
				current_Bottom = this.getBottom() - 2 * disY;
				if (current_Bottom < screen_H) {
					current_Bottom = screen_H;
					isControl_V = false;// 关闭垂直监听
				}
			}
			// 下边越界
			if (isControl_V && current_Bottom < screen_H) {
				current_Bottom = screen_H;
				current_Top = this.getTop() + 2 * disY;
				if (current_Top > 0) {
					current_Top = 0;
					isControl_V = false;// 关闭垂直监听
				}
			}

			// 左边越界
			if (isControl_H && current_Left >= 0) {
				current_Left = 0;
				current_Right = this.getRight() - 2 * disX;
				if (current_Right <= screen_W) {
					current_Right = screen_W;
					isControl_H = false;// 关闭
				}
			}
			// 右边越界
			if (isControl_H && current_Right <= screen_W) {
				current_Right = screen_W;
				current_Left = this.getLeft() + 2 * disX;
				if (current_Left >= 0) {
					current_Left = 0;
					isControl_H = false;// 关闭
				}
			}

			if (isControl_H || isControl_V) {
				this.setFrame(current_Left, current_Top, current_Right,
						current_Bottom);
			} else {
				this.setFrame(current_Left, current_Top, current_Right,
						current_Bottom);
				isScaleAnim = true;// 开启缩放动画
			}

		}

	}

	/***
	 * 缩放动画处理
	 */
	public void doScaleAnim() {
		myAsyncTask = new MyAsyncTask(screen_W, this.getWidth(),
				this.getHeight());
		myAsyncTask.setLTRB(this.getLeft(), this.getTop(), this.getRight(),
				this.getBottom());
		myAsyncTask.execute();
		isScaleAnim = false;// 关闭动画
	}

	/***
	 * 回缩动画執行
	 */
	class MyAsyncTask extends AsyncTask<Void, Integer, Void> {
		private int screen_W, current_Width, current_Height;

		private int left, top, right, bottom;

		private float scale_WH;// 宽高的比例

		/** 当前的位置属性 **/
		public void setLTRB(int left, int top, int right, int bottom) {
			this.left = left;
			this.top = top;
			this.right = right;
			this.bottom = bottom;
		}

		private float STEP = 8f;// 步伐

		private float step_H, step_V;// 水平步伐，垂直步伐

		public MyAsyncTask(int screen_W, int current_Width, int current_Height) {
			super();
			this.screen_W = screen_W;
			this.current_Width = current_Width;
			this.current_Height = current_Height;
			scale_WH = (float) current_Height / current_Width;
			step_H = STEP;
			step_V = scale_WH * STEP;
		}

		@Override
		protected Void doInBackground(Void... params) {

			while (current_Width <= screen_W) {

				left -= step_H;
				top -= step_V;
				right += step_H;
				bottom += step_V;

				current_Width += 2 * step_H;

				left = Math.max(left, start_Left);
				top = Math.max(top, start_Top);
				right = Math.min(right, start_Right);
				bottom = Math.min(bottom, start_Bottom);
                Log.e("jj", "top="+top+",bottom="+bottom+",left="+left+",right="+right);
				onProgressUpdate(new Integer[] { left, top, right, bottom });
				try {
					Thread.sleep(10);
				
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}

			return null;
		}

		@Override
		protected void onProgressUpdate(final Integer... values) {
			super.onProgressUpdate(values);
			mActivity.runOnUiThread(new Runnable() {
				@Override
				public void run() {
					setFrame(values[0], values[1], values[2], values[3]);
				}
			});

		}

	}

}

可直接拿来使用。然后在你的Activity中调用这个工具类。现在我把我工程里的Activity提出来！

HahItemActivity.java

package com.guyu.fragmenttabhost;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnLongClickListener;
import android.view.ViewGroup.LayoutParams;
import android.view.ViewTreeObserver;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.view.WindowManager;
import android.widget.ImageView;
import android.widget.PopupWindow;
import android.widget.TextView;
import android.widget.Toast;
import cn.guyu.NetUtils.ImageLoader;
import cn.guyu.util.DragImageView;

import com.example.fragmenttabhost.R;

public class HahItemActivity extends Activity {
	private int window_width, window_height;// 控件宽度
	private ViewTreeObserver HviewTreeObserver;
	private DragImageView dImageView;// 自定义控件
	private int state_height;// 状态栏的高度

	final private int SUCCESS = 0;
	final private int ERROR = 1;
	TextView tv, tv_save, tv_fenx;
	private ImageView iv_hahaItem,backHahaImag,saveHahaImag;

	Bitmap btImage, btImageUI,btImag;
	private FileOutputStream out;
	private PopupWindow mPopupWindow;

	private Handler handler = new Handler() {

		@Override
		public void handleMessage(Message msg) {
			super.handleMessage(msg);
			if (msg.what == SUCCESS) {
				btImageUI = (Bitmap) msg.obj;
				btImag =getBitmap(btImageUI, window_width, window_height);
				dImageView.setImageBitmap(btImag);
				
				// dImageView.setmActivity(this);
			} else {
				// Toast.makeText(HahItemActivity.this, "加载失败",
				// Toast.LENGTH_SHORT).show();
			}
		}

	};

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.hah_item);
		/** 获取可見区域高度 **/
		WindowManager manager = getWindowManager();
		window_width = manager.getDefaultDisplay().getWidth();
		window_height = manager.getDefaultDisplay().getHeight();
		dImageView = (DragImageView) findViewById(R.id.iv_hahaItem);
		backHahaImag = (ImageView) findViewById(R.id.haha_back_bt);
		saveHahaImag = (ImageView) findViewById(R.id.haha_save_bt);
		//dImageView.setmActivity(this);
		final String urlImage = (String) getIntent().getStringExtra("ImageUrl");

		new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					// btImage = getBitmap(urlImage);
					btImage = ImageLoader.getImage(urlImage);
				} catch (IOException e) {
					e.printStackTrace();
				}
				if (btImage != null) {
					Message msg = new Message();
					msg.what = SUCCESS;
					
					msg.obj = btImage;
					handler.sendMessage(msg);
				}
			}
		}).start();
		
		System.out.println("onclik_______________________________________________________");
		backHahaImag.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View arg0) {
				finish();
				
			}
		});
		
		saveHahaImag.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// 保存图片到sd卡中
				System.out.println(Environment.getExternalStorageDirectory()
						+ "/Cool/" + "000000000000000000000000000");
				// saveBitmapToSD(btImage);
				//mPopupWindow.dismiss();
				// File file = new
				// File(Environment.getExternalStorageDirectory(),
				// System.currentTimeMillis()+".jpg");

				if (Environment.getExternalStorageState().equals(
						Environment.MEDIA_MOUNTED))// 判断是否可以对SDcard进行操作
				{ // 获取SDCard指定目录下
					String sdCardDir = Environment
							.getExternalStorageDirectory() + "/CoolImage/";
					File dirFile = new File(sdCardDir);
					if (!dirFile.exists()) {
						dirFile.mkdirs();
					}
					File file = new File(sdCardDir, System.currentTimeMillis()
							+ ".jpg");// 在SDcard的目录下创建图片文

					try {
						out = new FileOutputStream(file);
						btImageUI.compress(Bitmap.CompressFormat.JPEG, 90, out);
						System.out
								.println("_____________sd__________________________");
					} catch (FileNotFoundException e) {
						e.printStackTrace();
					}
					try {
						out.flush();
						out.close();
					} catch (IOException e) {
						e.printStackTrace();
					}
					Toast.makeText(
							HahItemActivity.this,
							"已经保存至" + Environment.getExternalStorageDirectory()
									+ "/CoolImage/" + "目录下", Toast.LENGTH_SHORT)
							.show();
				}
			}
		});
		
		
		
		
		
		
		dImageView.setmActivity(this);
		HviewTreeObserver = dImageView.getViewTreeObserver();
		HviewTreeObserver.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {

					public void onGlobalLayout() {
						if (state_height == 0) {
							// 获取状况栏高度
							Rect frameH = new Rect();
							getWindow().getDecorView()
									.getWindowVisibleDisplayFrame(frameH);
							state_height = frameH.top;
							dImageView.setScreen_H(window_height - state_height);
							dImageView.setScreen_W(window_width);
						}
					}
				});
		

	
		
		
		
/*	多触电事件，好像与这个有冲突
		dImageView.setOnClickListener(new OnClickListener() {
			public void onClick(View arg0) {
				finish();
				// Toast.makeText(HahItemActivity.this,"你点我干嘛〉〉〉〉",
				// Toast.LENGTH_SHORT).show();

			}
		});

		dImageView.setOnLongClickListener(new OnLongClickListener() {

			public boolean onLongClick(View arg0) {
				// Toast.makeText(HahItemActivity.this,"你摸我干嘛",
				// Toast.LENGTH_SHORT).show();
				showPopupWindow();
				return false;
			}
		});*/

	}
	public static Bitmap getBitmap(Bitmap bitmap, int screenWidth,
			int screenHight) {
		int w = bitmap.getWidth();
		int h = bitmap.getHeight();
		Log.e("jj", "图片宽度" + w + ",screenWidth=" + screenWidth);
		Matrix matrix = new Matrix();
		float scale = (float) screenWidth / w;
		float scale2 = (float) screenHight / h;
		// scale = scale < scale2 ? scale : scale2;
		// 保证图片不变形.
		matrix.postScale(scale, scale);
		// w,h是原图的属性.
		return Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);
	}
/*	因为添加了图片缩放，避免造成触摸手势与点击事件的冲突，这里抛弃使用长按显示popupwindow,直接使用按钮Button.
 * public  void showPopupWindow() {
		// Context mContext = HahItemActivity.this;
		LayoutInflater mLayoutInflater = (LayoutInflater) this
				.getSystemService(LAYOUT_INFLATER_SERVICE);
		// 保存转发等视图
		View xuanz_popunwindwow = mLayoutInflater.inflate(
				R.layout.popwindow_image, null);
		// 转化为popunwindow
		mPopupWindow = new PopupWindow(xuanz_popunwindwow,
				LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);

		mPopupWindow.setBackgroundDrawable(new BitmapDrawable());
		mPopupWindow.setFocusable(true);
		mPopupWindow.setOutsideTouchable(true);
		mPopupWindow.update();
		// 设置显示
		mPopupWindow.showAtLocation(findViewById(R.id.hahaimage_pop_layout),
				Gravity.CENTER, 0, 0);
		tv_save = (TextView) xuanz_popunwindwow
				.findViewById(R.id.pop_save_image);
		// tv_save = (TextView)findViewById(R.id.pop_save_image);

		tv_save.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				// 保存图片到sd卡中
				System.out.println(Environment.getExternalStorageDirectory()
						+ "/Cool/" + "000000000000000000000000000");
				// saveBitmapToSD(btImage);
				mPopupWindow.dismiss();
				// File file = new
				// File(Environment.getExternalStorageDirectory(),
				// System.currentTimeMillis()+".jpg");

				if (Environment.getExternalStorageState().equals(
						Environment.MEDIA_MOUNTED))// 判断是否可以对SDcard进行操作
				{ // 获取SDCard指定目录下
					String sdCardDir = Environment
							.getExternalStorageDirectory() + "/CoolImage/";
					File dirFile = new File(sdCardDir);
					if (!dirFile.exists()) {
						dirFile.mkdirs();
					}
					File file = new File(sdCardDir, System.currentTimeMillis()
							+ ".jpg");// 在SDcard的目录下创建图片文

					try {
						out = new FileOutputStream(file);
						btImage.compress(Bitmap.CompressFormat.JPEG, 90, out);
						System.out
								.println("_____________sd__________________________");
					} catch (FileNotFoundException e) {
						e.printStackTrace();
					}
					try {
						out.flush();
						out.close();
					} catch (IOException e) {
						e.printStackTrace();
					}
					Toast.makeText(
							HahItemActivity.this,
							"保存已经至" + Environment.getExternalStorageDirectory()
									+ "/CoolImage/" + "目录下", Toast.LENGTH_SHORT)
							.show();
				}
			}
		});

	}*/
}

hah_item.xml  采用真布局的格式

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

     <cn.guyu.util.DragImageView
         android:layout_gravity="center_vertical"
       android:id="@+id/iv_hahaItem"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:src="@drawable/sbb"
     android:scaleType="fitXY"
       />
    
    <LinearLayout
        
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="15dp"
        android:layout_gravity="top"
        android:background="@android:color/transparent" >

        <ImageView
             android:focusable="true"
            android:id="@+id/haha_back_bt"
               android:layout_gravity="center"
            android:layout_width="31dp"
            android:layout_height="20dp"
            android:layout_weight="1"
            android:src="@drawable/haha_back" />
		<TextView 
	   		  android:layout_width="wrap_content"
            android:layout_height="wrap_content"
	     android:layout_weight="5"
	 	   />
     
        <ImageView
            android:focusable="true"
            android:id="@+id/haha_save_bt"
            android:layout_gravity="center"
             android:layout_width="31dp"
           	 android:layout_height="20dp"
          	 android:layout_weight="1"
            android:src="@drawable/haha_save" />
    </LinearLayout>

</FrameLayout>

效果与