android 图片的缩放

//获得Bitmap的高和宽
int bmpWidth=bmp.getWidth();
int bmpHeight=bmp.getHeight();
 
//设置缩小比例
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);


转自
http://www.cnblogs.com/llm-android/archive/2012/02/19/2357821.html#commentform

图片处理的相关代码（忘了从哪儿转载的了，很感谢博主）：

package com.wwj.sb.utils;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.CompressFormat;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.ColorMatrix;
import android.graphics.ColorMatrixColorFilter;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
/**
 * 图片工具类
 * @author wwj
 * 2013/7/3
 */
public class ImageUtil {
 /**图片的八个位置**/
 public static final int TOP = 0;	 //上
 public static final int BOTTOM = 1;	 //下
 public static final int LEFT = 2;	 //左
 public static final int RIGHT = 3;	 //右
 public static final int LEFT_TOP = 4;	 //左上
 public static final int LEFT_BOTTOM = 5;	//左下
 public static final int RIGHT_TOP = 6;	 //右上
 public static final int RIGHT_BOTTOM = 7;	//右下
 
 /**
  * 图像的放大缩小方法
  * @param src	 源位图对象
  * @param scaleX	宽度比例系数
  * @param scaleY	高度比例系数
  * @return 返回位图对象
  */
 public static Bitmap zoomBitmap(Bitmap src, float scaleX, float scaleY) {
  Matrix matrix = new Matrix();
  matrix.setScale(scaleX, scaleY);
  Bitmap t_bitmap = Bitmap.createBitmap(src, 0, 0, src.getWidth(), src.getHeight(), matrix, true); 
  return t_bitmap;
 }
 
 /**
  * 图像放大缩小--根据宽度和高度
  * @param src
  * @param width
  * @param height
  * @return
  */
 public static Bitmap zoomBimtap(Bitmap src, int width, int height) {
  return Bitmap.createScaledBitmap(src, width, height, true);
 }
 
 /**
  * 将Drawable转为Bitmap对象
  * @param drawable
  * @return
  */
 public static Bitmap drawableToBitmap(Drawable drawable) {
  return ((BitmapDrawable)drawable).getBitmap();
 }
 
 
 /**
  * 将Bitmap转换为Drawable对象
  * @param bitmap
  * @return
  */
 public static Drawable bitmapToDrawable(Bitmap bitmap) {
  Drawable drawable = new BitmapDrawable(bitmap);
  return drawable;
 }
 
 /**
  * Bitmap转byte[]
  * @param bitmap
  * @return
  */
 public static byte[] bitmapToByte(Bitmap bitmap) {
  ByteArrayOutputStream out = new ByteArrayOutputStream();
  bitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
  return out.toByteArray();
 }
 
 /**
  * byte[]转Bitmap
  * @param data
  * @return
  */
 public static Bitmap byteToBitmap(byte[] data) {
  if(data.length != 0) {
   return BitmapFactory.decodeByteArray(data, 0, data.length);
  }
  return null;
 }
 
 /**
  * 绘制带圆角的图像
  * @param src
  * @param radius
  * @return
  */
 public static Bitmap createRoundedCornerBitmap(Bitmap src, int radius) {
  final int w = src.getWidth();
  final int h = src.getHeight();
  // 高清量32位图
  Bitmap bitmap = Bitmap.createBitmap(w, h, Config.ARGB_8888);
  Paint paint = new Paint();
  Canvas canvas = new Canvas(bitmap);
  canvas.drawARGB(0, 0, 0, 0);
  paint.setColor(0xff424242);
  // 防止边缘的锯齿
  paint.setFilterBitmap(true);
  Rect rect = new Rect(0, 0, w, h);
  RectF rectf = new RectF(rect);
  // 绘制带圆角的矩形
  canvas.drawRoundRect(rectf, radius, radius, paint);
 
  // 取两层绘制交集，显示上层
  paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
  // 绘制图像
  canvas.drawBitmap(src, rect, rect, paint);
  return bitmap;
 }
 
 /**
  * 创建选中带提示图片
  * @param context
  * @param srcId
  * @param tipId
  * @return
  */
 public static Drawable createSelectedTip(Context context, int srcId, int tipId) {
  Bitmap src = BitmapFactory.decodeResource(context.getResources(), srcId);
  Bitmap tip = BitmapFactory.decodeResource(context.getResources(), tipId);
  final int w = src.getWidth();
  final int h = src.getHeight();
  Bitmap bitmap = Bitmap.createBitmap(w, h, Config.ARGB_8888);
  Paint paint = new Paint();
  Canvas canvas = new Canvas(bitmap);
  //绘制原图
  canvas.drawBitmap(src, 0, 0, paint);
  //绘制提示图片
  canvas.drawBitmap(tip, (w - tip.getWidth()), 0, paint);
  return bitmapToDrawable(bitmap);
 }
 
 /**
  * 带倒影的图像
  * @param src
  * @return
  */
 public static Bitmap createReflectionBitmap(Bitmap src) {
  // 两个图像间的空隙
  final int spacing = 4;
  final int w = src.getWidth();
  final int h = src.getHeight();
  // 绘制高质量32位图
  Bitmap bitmap = Bitmap.createBitmap(w, h + h / 2 + spacing, Config.ARGB_8888);
  // 创建燕X轴的倒影图像
  Matrix m = new Matrix();
  m.setScale(1, -1);
  Bitmap t_bitmap = Bitmap.createBitmap(src, 0, h / 2, w, h / 2, m, true);
 
  Canvas canvas = new Canvas(bitmap);
  Paint paint = new Paint();
  //	绘制原图像
  canvas.drawBitmap(src, 0, 0, paint);
  // 绘制倒影图像
  canvas.drawBitmap(t_bitmap, 0, h + spacing, paint);
  // 线性渲染-沿Y轴高到低渲染
  Shader shader = new LinearGradient(0, h + spacing, 0, h + spacing + h / 2, 0x70ffffff, 0x00ffffff, Shader.TileMode.MIRROR);
  paint.setShader(shader);
  // 取两层绘制交集，显示下层。
  paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
  // 绘制渲染倒影的矩形
  canvas.drawRect(0, h + spacing, w, h + h / 2 + spacing, paint);
  return bitmap;
 }
 
 
 /**
  * 独立的倒影图像
  * @param src
  * @return
  */
 public static Bitmap createReflectionBitmapForSingle(Bitmap src) {
  final int w = src.getWidth();
  final int h = src.getHeight();
  // 绘制高质量32位图
  Bitmap bitmap = Bitmap.createBitmap(w, h / 2, Config.ARGB_8888);
  // 创建沿X轴的倒影图像
  Matrix m = new Matrix();
  m.setScale(1, -1);
  Bitmap t_bitmap = Bitmap.createBitmap(src, 0, h / 2, w, h / 2, m, true);
  Canvas canvas = new Canvas(bitmap);
  Paint paint = new Paint();
  // 绘制倒影图像
  canvas.drawBitmap(t_bitmap, 0, 0, paint);
  // 线性渲染-沿Y轴高到低渲染
  Shader shader = new LinearGradient(0, 0, 0, h / 2, 0x70ffffff,
    0x00ffffff, Shader.TileMode.MIRROR);
  paint.setShader(shader);
  // 取两层绘制交集。显示下层。
  paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
  // 绘制渲染倒影的矩形
  canvas.drawRect(0, 0, w, h / 2, paint);
  return bitmap;
 }
 
 
 public static Bitmap createGreyBitmap(Bitmap src) {
  final int w = src.getWidth();
  final int h = src.getHeight();
  Bitmap bitmap = Bitmap.createBitmap(w, h, Config.ARGB_8888);
  Canvas canvas = new Canvas(bitmap);
  Paint paint = new Paint();
  // 颜色变换的矩阵
  ColorMatrix matrix = new ColorMatrix();
  // saturation 饱和度值，最小可设为0，此时对应的是灰度图；为1表示饱和度不变，设置大于1，就显示过饱和
  matrix.setSaturation(0);
  ColorMatrixColorFilter filter = new ColorMatrixColorFilter(matrix);
  paint.setColorFilter(filter);
  canvas.drawBitmap(src, 0, 0, paint);
  return bitmap;
 }
 
 /**
  * 保存图片
  * @param src
  * @param filepath
  * @param format:[Bitmap.CompressFormat.PNG,Bitmap.CompressFormat.JPEG]
  * @return
  */
 public static boolean saveImage(Bitmap src, String filepath, CompressFormat format) {
  boolean rs = false;
  File file = new File(filepath);
  try {
   FileOutputStream out = new FileOutputStream(file);
   if(src.compress(format, 100, out)) {
    out.flush();	//写入流
   }
   out.close();
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
  return rs;
 }
 
 /**
  * 添加水印效果
  * @param src	 源位图
  * @param watermark	水印
  * @param direction	方向
  * @param spacing 间距
  * @return
  */
 public static Bitmap createWatermark(Bitmap src, Bitmap watermark, int direction, int spacing) {
  final int w = src.getWidth();
  final int h = src.getHeight();
  Bitmap bitmap = Bitmap.createBitmap(w, h, Config.ARGB_8888);
  Canvas canvas = new Canvas(bitmap);
  canvas.drawBitmap(src, 0, 0, null);
  if(direction == LEFT_TOP) {
   canvas.drawBitmap(watermark, spacing, spacing, null);
  } else if(direction == LEFT_BOTTOM){
   canvas.drawBitmap(watermark, spacing, h - watermark.getHeight() - spacing, null);
  } else if(direction == RIGHT_TOP) {
   canvas.drawBitmap(watermark, w - watermark.getWidth() - spacing, spacing, null);
  } else if(direction == RIGHT_BOTTOM) {
   canvas.drawBitmap(watermark, w - watermark.getWidth() - spacing, h - watermark.getHeight() - spacing, null);
  }
  return bitmap;
 }
 
 
 /**
  * 合成图像
  * @param direction
  * @param bitmaps
  * @return
  */
 public static Bitmap composeBitmap(int direction, Bitmap... bitmaps) {
  if(bitmaps.length < 2) {
   return null;
  }
  Bitmap firstBitmap = bitmaps[0];
  for (int i = 0; i < bitmaps.length; i++) {
   firstBitmap = composeBitmap(firstBitmap, bitmaps[i], direction);
  }
  return firstBitmap;
 }
 /**
  * 合成两张图像
  * @param firstBitmap
  * @param secondBitmap
  * @param direction
  * @return
  */
 private static Bitmap composeBitmap(Bitmap firstBitmap, Bitmap secondBitmap,
   int direction) {
  if(firstBitmap == null) {
   return null;
  }
  if(secondBitmap == null) {
   return firstBitmap;
  }
  final int fw = firstBitmap.getWidth();
  final int fh = firstBitmap.getHeight();
  final int sw = secondBitmap.getWidth();
  final int sh = secondBitmap.getHeight();
  Bitmap bitmap = null;
  Canvas canvas = null;
  if(direction == TOP) {
   bitmap = Bitmap.createBitmap(sw > fw ? sw : fw, fh + sh, Config.ARGB_8888);
   canvas = new Canvas(bitmap);
   canvas.drawBitmap(secondBitmap, 0, 0, null);
   canvas.drawBitmap(firstBitmap, 0, sh, null);
  } else if(direction == BOTTOM) {
   bitmap = Bitmap.createBitmap(fw > sw ? fw : sw, fh + sh, Config.ARGB_8888);
   canvas = new Canvas(bitmap);
   canvas.drawBitmap(firstBitmap, 0, 0, null);
   canvas.drawBitmap(secondBitmap, 0, fh, null);
  } else if(direction == LEFT) {
   bitmap = Bitmap.createBitmap(fw + sw, sh > fh ? sh : fh, Config.ARGB_8888);
   canvas = new Canvas(bitmap);
   canvas.drawBitmap(secondBitmap, 0, 0, null);
   canvas.drawBitmap(firstBitmap, sw, 0, null);
  } else if(direction == RIGHT) {
   bitmap = Bitmap.createBitmap(fw + sw, fh > sh ? fh : sh,
     Config.ARGB_8888);
   canvas = new Canvas(bitmap);
   canvas.drawBitmap(firstBitmap, 0, 0, null);
   canvas.drawBitmap(secondBitmap, fw, 0, null);
  }
  return bitmap;
 }
 
 
}