将一个图片切割成多个图片

有种场景，我们想将一个图片切割成多个图片。比如我们在开发一个拼图的游戏，就首先要对图片进行切割。
以下是封装好的两个类，可以实现图片的切割。仅供参考和学习。
一个是ImagePiece类，此类保存了一个Bitmap对象和一个标识图片的顺序索引的int变量。

import android.graphics.Bitmap; public class ImagePiece {       public int index = 0;            public Bitmap bitmap = null;  }

一个是ImageSplitter类，有一个静态方法split，传入的参数是要切割的Bitmap对象，和横向和竖向的切割片数。比如传入的是3、3，则横竖向都切割成3片，最终会将整个图片切割成3X3=9片。

import java.util.ArrayList;  import java.util.List;    import android.graphics.Bitmap;    public class ImageSplitter {        public static List<ImagePiece> split(Bitmap bitmap, int xPiece, int yPiece) {            List<ImagePiece> pieces = new ArrayList<ImagePiece>(xPiece * yPiece);          int width = bitmap.getWidth();          int height = bitmap.getHeight();          int pieceWidth = width / 3;          int pieceHeight = height / 3;          for (int i = 0; i < yPiece; i++) {              for (int j = 0; j < xPiece; j++) {                  ImagePiece piece = new ImagePiece();                  piece.index = j + i * xPiece;                  int xValue = j * pieceWidth;                  int yValue = i * pieceHeight;                  piece.bitmap = Bitmap.createBitmap(bitmap, xValue, yValue,                          pieceWidth, pieceHeight);                  pieces.add(piece);              }          }            return pieces;      }    }

1、图标加灰色过滤；
2、android的图片资源默认是静态的，单实例；如果两个IM好友的头像一样，最简单的都是用的软件自带头像，有一个在线，一个离线，直接改变头像的灰度，则两个用户的头像都会变灰或者在线，答案是：Drawable.mutate()。

Drawable mDrawable = context.getResources().getDrawable(R.drawable.face_icon);  //Make this drawable mutable.  //A mutable drawable is guaranteed to not share its state with any other drawable.  mDrawable.mutate();  ColorMatrix cm = new ColorMatrix();  cm.setSaturation(0);  ColorMatrixColorFilter cf = new ColorMatrixColorFilter(cm);  mDrawable.setColorFilter(cf);

生成缩略图，抠自android launcher源码：

/* * Copyright (C) 2008 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package com.android.launcher;import android.graphics.drawable.BitmapDrawable;import android.graphics.drawable.Drawable;import android.graphics.drawable.PaintDrawable;import android.graphics.Bitmap;import android.graphics.PixelFormat;import android.graphics.Canvas;import android.graphics.PaintFlagsDrawFilter;import android.graphics.Paint;import android.graphics.Rect;import android.content.res.Resources;import android.content.Context;/** * Various utilities shared amongst the Launcher's classes. */final class Utilities {    private static int sIconWidth = -1;    private static int sIconHeight = -1;    private static final Paint sPaint = new Paint();    private static final Rect sBounds = new Rect();    private static final Rect sOldBounds = new Rect();    private static Canvas sCanvas = new Canvas();    static {        sCanvas.setDrawFilter(new PaintFlagsDrawFilter(Paint.DITHER_FLAG,                Paint.FILTER_BITMAP_FLAG));    }    /**     * Returns a Drawable representing the thumbnail of the specified Drawable.     * The size of the thumbnail is defined by the dimension     * android.R.dimen.launcher_application_icon_size.     *     * This method is not thread-safe and should be invoked on the UI thread only.     *     * @param icon The icon to get a thumbnail of.     * @param context The application's context.     *     * @return A thumbnail for the specified icon or the icon itself if the     *         thumbnail could not be created.      */    static Drawable createIconThumbnail(Drawable icon, Context context) {        if (sIconWidth == -1) {            final Resources resources = context.getResources();            sIconWidth = sIconHeight = (int) resources.getDimension(android.R.dimen.app_icon_size);        }        int width = sIconWidth;        int height = sIconHeight;        float scale = 1.0f;        if (icon instanceof PaintDrawable) {            PaintDrawable painter = (PaintDrawable) icon;            painter.setIntrinsicWidth(width);            painter.setIntrinsicHeight(height);        } else if (icon instanceof BitmapDrawable) {            // Ensure the bitmap has a density.            BitmapDrawable bitmapDrawable = (BitmapDrawable) icon;            Bitmap bitmap = bitmapDrawable.getBitmap();            if (bitmap.getDensity() == Bitmap.DENSITY_NONE) {                bitmapDrawable.setTargetDensity(context.getResources().getDisplayMetrics());            }        }        int iconWidth = icon.getIntrinsicWidth();        int iconHeight = icon.getIntrinsicHeight();        if (width > 0 && height > 0) {            if (width < iconWidth || height < iconHeight || scale != 1.0f) {                final float ratio = (float) iconWidth / iconHeight;                if (iconWidth > iconHeight) {                    height = (int) (width / ratio);                } else if (iconHeight > iconWidth) {                    width = (int) (height * ratio);                }                final Bitmap.Config c = icon.getOpacity() != PixelFormat.OPAQUE ?                            Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565;                final Bitmap thumb = Bitmap.createBitmap(sIconWidth, sIconHeight, c);                final Canvas canvas = sCanvas;                canvas.setBitmap(thumb);                // Copy the old bounds to restore them later                // If we were to do oldBounds = icon.getBounds(),                // the call to setBounds() that follows would                // change the same instance and we would lose the                // old bounds                sOldBounds.set(icon.getBounds());                final int x = (sIconWidth - width) / 2;                final int y = (sIconHeight - height) / 2;                icon.setBounds(x, y, x + width, y + height);                icon.draw(canvas);                icon.setBounds(sOldBounds);                icon = new FastBitmapDrawable(thumb);            } else if (iconWidth < width && iconHeight < height) {                final Bitmap.Config c = Bitmap.Config.ARGB_8888;                final Bitmap thumb = Bitmap.createBitmap(sIconWidth, sIconHeight, c);                final Canvas canvas = sCanvas;                canvas.setBitmap(thumb);                sOldBounds.set(icon.getBounds());                final int x = (width - iconWidth) / 2;                final int y = (height - iconHeight) / 2;                icon.setBounds(x, y, x + iconWidth, y + iconHeight);                icon.draw(canvas);                icon.setBounds(sOldBounds);                icon = new FastBitmapDrawable(thumb);            }        }        return icon;    }    /**     * Returns a Bitmap representing the thumbnail of the specified Bitmap.     * The size of the thumbnail is defined by the dimension     * android.R.dimen.launcher_application_icon_size.     *     * This method is not thread-safe and should be invoked on the UI thread only.     *     * @param bitmap The bitmap to get a thumbnail of.     * @param context The application's context.     *     * @return A thumbnail for the specified bitmap or the bitmap itself if the     *         thumbnail could not be created.     */    static Bitmap createBitmapThumbnail(Bitmap bitmap, Context context) {        if (sIconWidth == -1) {            final Resources resources = context.getResources();            sIconWidth = sIconHeight = (int) resources.getDimension(                    android.R.dimen.app_icon_size);        }        int width = sIconWidth;        int height = sIconHeight;        final int bitmapWidth = bitmap.getWidth();        final int bitmapHeight = bitmap.getHeight();        if (width > 0 && height > 0) {            if (width < bitmapWidth || height < bitmapHeight) {                final float ratio = (float) bitmapWidth / bitmapHeight;                    if (bitmapWidth > bitmapHeight) {                    height = (int) (width / ratio);                } else if (bitmapHeight > bitmapWidth) {                    width = (int) (height * ratio);                }                    final Bitmap.Config c = (width == sIconWidth && height == sIconHeight) ?                        bitmap.getConfig() : Bitmap.Config.ARGB_8888;                final Bitmap thumb = Bitmap.createBitmap(sIconWidth, sIconHeight, c);                final Canvas canvas = sCanvas;                final Paint paint = sPaint;                canvas.setBitmap(thumb);                paint.setDither(false);                paint.setFilterBitmap(true);                sBounds.set((sIconWidth - width) / 2, (sIconHeight - height) / 2, width, height);                sOldBounds.set(0, 0, bitmapWidth, bitmapHeight);                canvas.drawBitmap(bitmap, sOldBounds, sBounds, paint);                return thumb;            } else if (bitmapWidth < width || bitmapHeight < height) {                final Bitmap.Config c = Bitmap.Config.ARGB_8888;                final Bitmap thumb = Bitmap.createBitmap(sIconWidth, sIconHeight, c);                final Canvas canvas = sCanvas;                final Paint paint = sPaint;                canvas.setBitmap(thumb);                paint.setDither(false);                paint.setFilterBitmap(true);                canvas.drawBitmap(bitmap, (sIconWidth - bitmapWidth) / 2,                        (sIconHeight - bitmapHeight) / 2, paint);                return thumb;            }        }        return bitmap;    }}

//Android Matrix类实现镜像方法public void drawRegion(Image image_src,int x_src, int y_src,int width, int height,int transform,int x_dest, int y_dest,int anchor){if((anchor&VCENTER) != 0){y_dest -= height/2;}else if((anchor&BOTTOM) != 0){y_dest -= height;}if((anchor&RIGHT) != 0){x_dest -= width;}else if((anchor&HCENTER) != 0){x_dest -= width/2;}Bitmap newMap = Bitmap.createBitmap(image_src.getBitmap(), x_src, y_src, width, height);Matrix mMatrix = new Matrix();Matrix temp = new Matrix();Matrix temp2 = new Matrix();float[] mirrorY = {-1, 0, 0,0, 1, 0,0, 0, 1};temp.setValues(mirrorY);switch(transform){case Sprite.TRANS_NONE:break;case Sprite.TRANS_ROT90:mMatrix.setRotate(90,width/2, height/2);break;case Sprite.TRANS_ROT180:mMatrix.setRotate(180,width/2, height/2);break;case Sprite.TRANS_ROT270:mMatrix.setRotate(270,width/2, height/2);break;case Sprite.TRANS_MIRROR:mMatrix.postConcat(temp);break;case Sprite.TRANS_MIRROR_ROT90:mMatrix.postConcat(temp);mMatrix.setRotate(90,width/2, height/2);break;case Sprite.TRANS_MIRROR_ROT180:mMatrix.postConcat(temp);mMatrix.setRotate(180,width/2, height/2);break;case Sprite.TRANS_MIRROR_ROT270:mMatrix.postConcat(temp);mMatrix.setRotate(270,width/2, height/2);break;}mMatrix.setTranslate(x_dest, y_dest);canvas.drawBitmap(newMap, mMatrix, mPaint);}

//图片Url保存为位图并进行缩放操作//通过传入图片url获取位图方法public Bitmap returnBitMap(String url) {URL myFileUrl = null;Bitmap bitmap = null;try {myFileUrl = new URL(url);} catch (MalformedURLException e) {e.printStackTrace();}try {HttpURLConnection conn = (HttpURLConnection) myFileUrl.openConnection();conn.setDoInput(true);conn.connect();InputStream is = conn.getInputStream();bitmap = BitmapFactory.decodeStream(is);is.close();} catch (IOException e) {e.printStackTrace();}Log.v(tag, bitmap.toString());return bitmap;}//通过传入位图,新的宽.高比进行位图的缩放操作public static Drawable resizeImage(Bitmap bitmap, int w, int h) {// load the origial BitmapBitmap BitmapOrg = bitmap;int width = BitmapOrg.getWidth();int height = BitmapOrg.getHeight();int newWidth = w;int newHeight = h;Log.v(tag, String.valueOf(width));Log.v(tag, String.valueOf(height));Log.v(tag, String.valueOf(newWidth));Log.v(tag, String.valueOf(newHeight));// calculate the scalefloat scaleWidth = ((float) newWidth) / width;float scaleHeight = ((float) newHeight) / height;// create a matrix for the manipulationMatrix matrix = new Matrix();// resize the Bitmapmatrix.postScale(scaleWidth, scaleHeight);// if you want to rotate the Bitmap// matrix.postRotate(45);// recreate the new BitmapBitmap resizedBitmap = Bitmap.createBitmap(BitmapOrg, 0, 0, width,height, matrix, true);// make a Drawable from Bitmap to allow to set the Bitmap// to the ImageView, ImageButton or what everreturn new BitmapDrawable(resizedBitmap);}

1.图片加载方法，方便用户加载图片/**** 加载本地图片* @param context：主运行函数实例* @param bitAdress：图片地址，一般指向R下的drawable目录* @return*/public final Bitmap CreatImage(Context context, int bitAdress) {Bitmap bitmaptemp = null;bitmaptemp = BitmapFactory.decodeResource(context.getResources(),bitAdress);return bitmaptemp;}2.图片平均分割方法，将大图平均分割为N行N列，方便用户使用/**** 图片分割** @param g* ：画布* @param paint* ：画笔* @param imgBit* ：图片* @param x* ：X轴起点坐标* @param y* ：Y轴起点坐标* @param w* ：单一图片的宽度* @param h* ：单一图片的高度* @param line* ：第几列* @param row* ：第几行*/public final void cuteImage(Canvas g, Paint paint, Bitmap imgBit, int x,int y, int w, int h, int line, int row) {g.clipRect(x, y, x + w, h + y);g.drawBitmap(imgBit, x – line * w, y – row * h, paint);g.restore();}3.图片缩放，对当前图片进行缩放处理/**** 图片的缩放方法** @param bgimage* ：源图片资源* @param newWidth* ：缩放后宽度* @param newHeight* ：缩放后高度* @return*/public Bitmap zoomImage(Bitmap bgimage, int newWidth, int newHeight) {// 获取这个图片的宽和高int width = bgimage.getWidth();int height = bgimage.getHeight();// 创建操作图片用的matrix对象Matrix matrix = new Matrix();// 计算缩放率，新尺寸除原始尺寸float scaleWidth = ((float) newWidth) / width;float scaleHeight = ((float) newHeight) / height;// 缩放图片动作matrix.postScale(scaleWidth, scaleHeight);Bitmap bitmap = Bitmap.createBitmap(bgimage, 0, 0, width, height,matrix, true);return bitmap;}4.绘制带有边框的文字，一般在游戏中起文字的美化作用/**** 绘制带有边框的文字** @param strMsg* ：绘制内容* @param g* ：画布* @param paint* ：画笔* @param setx* ：：X轴起始坐标* @param sety* ：Y轴的起始坐标* @param fg* ：前景色* @param bg* ：背景色*/public void drawText(String strMsg, Canvas g, Paint paint, int setx,int sety, int fg, int bg) {paint.setColor(bg);g.drawText(strMsg, setx + 1, sety, paint);g.drawText(strMsg, setx, sety – 1, paint);g.drawText(strMsg, setx, sety + 1, paint);g.drawText(strMsg, setx – 1, sety, paint);paint.setColor(fg);g.drawText(strMsg, setx, sety, paint);g.restore();}5.Android 图片透明度处理代码/*** 图片透明度处理** @param sourceImg*            原始图片* @param number*            透明度* @return*/public static Bitmap setAlpha(Bitmap sourceImg, int number) {int[] argb = new int[sourceImg.getWidth() * sourceImg.getHeight()];sourceImg.getPixels(argb, 0, sourceImg.getWidth(), 0, 0,sourceImg.getWidth(), sourceImg.getHeight());// 获得图片的ARGB值number = number * 255 / 100;for (int i = 0; i < argb.length; i++) {argb = (number << 24) | (argb & 0×00FFFFFF);// 修改最高2位的值}sourceImg = Bitmap.createBitmap(argb, sourceImg.getWidth(), sourceImg.getHeight(), Config.ARGB_8888);return sourceImg;}6.图片翻转Resources res = this.getContext().getResources();img = BitmapFactory.decodeResource(res, R.drawable.slogo);Matrix matrix = new Matrix();matrix.postRotate(90);        /*翻转90度*/int width = img.getWidth();int height = img.getHeight();r_img = Bitmap.createBitmap(img, 0, 0, width, height, matrix, true);

import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.LinearGradient;import android.graphics.Matrix;import android.graphics.Paint;import android.graphics.PixelFormat;import android.graphics.PorterDuffXfermode;import android.graphics.Rect;import android.graphics.RectF;import android.graphics.Bitmap.Config;import android.graphics.PorterDuff.Mode;import android.graphics.Shader.TileMode;import android.graphics.drawable.Drawable;/*** * @author superdev* @version 1.0**/public class ImageUtil {/*** 放大缩小图片*/public static Bitmap zoomBitmap(Bitmap bitmap, int w, int h) {   int width = bitmap.getWidth();   int height = bitmap.getHeight();   Matrix matrix = new Matrix();   float scaleWidht = ((float) w / width);   float scaleHeight = ((float) h / height);   matrix.postScale(scaleWidht, scaleHeight);   Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);   return newbmp;}/*** 将Drawable转化为Bitmap*/public static Bitmap drawableToBitmap(Drawable drawable) {   int width = drawable.getIntrinsicWidth();   int height = drawable.getIntrinsicHeight();   Bitmap bitmap = Bitmap.createBitmap(width, height, drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565);   Canvas canvas = new Canvas(bitmap);   drawable.setBounds(0, 0, width, height);   drawable.draw(canvas);   return bitmap;}/*** 获得圆角图片的方法*/public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, float roundPx) {   Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Config.ARGB_8888);   Canvas canvas = new Canvas(output);   final int color = 0xff424242;   final Paint paint = new Paint();   final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());   final RectF rectF = new RectF(rect);   paint.setAntiAlias(true);   canvas.drawARGB(0, 0, 0, 0);   paint.setColor(color);   canvas.drawRoundRect(rectF, roundPx, roundPx, paint);   paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));   canvas.drawBitmap(bitmap, rect, rect, paint);   return output;}/*** 获得带倒影的图片方法*/public static Bitmap createReflectionImageWithOrigin(Bitmap bitmap) {   final int reflectionGap = 4;   int width = bitmap.getWidth();   int height = bitmap.getHeight();   Matrix matrix = new Matrix();   matrix.preScale(1, -1);   Bitmap reflectionImage = Bitmap.createBitmap(bitmap, 0, height / 2, width, height / 2, matrix, false);   Bitmap bitmapWithReflection = Bitmap.createBitmap(width, (height + height / 2), Config.ARGB_8888);   Canvas canvas = new Canvas(bitmapWithReflection);   canvas.drawBitmap(bitmap, 0, 0, null);   Paint deafalutPaint = new Paint();   canvas.drawRect(0, height, width, height + reflectionGap, deafalutPaint);   canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);   Paint paint = new Paint();   LinearGradient shader = new LinearGradient(0, bitmap.getHeight(), 0, bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff, 0x00ffffff, TileMode.CLAMP);   paint.setShader(shader);   // Set the Transfer mode to be porter duff and destination in   paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));   // Draw a rectangle using the paint with our linear gradient   canvas.drawRect(0, height, width, bitmapWithReflection.getHeight() + reflectionGap, paint);   return bitmapWithReflection;}}

private byte[] Bitmap2Bytes(Bitmap bm){   ByteArrayOutputStream baos = new ByteArrayOutputStream();   bm.compress(Bitmap.CompressFormat.PNG, 100, baos);   return baos.toByteArray();}private Bitmap Bytes2Bimap(byte[] b){    if(b.length!=0){    return BitmapFactory.decodeByteArray(b, 0, b.length);    }    else {    return null;    }  } /**     * create the bitmap from a byte array     *生成水印图片     * @param src the bitmap object you want proecss     * @param watermark the water mark above the src     * @return return a bitmap object ,if paramter's length is 0,return null     */    private Bitmap createBitmap( Bitmap src, Bitmap watermark )    {        String tag = "createBitmap";        Log.d( tag, "create a new bitmap" );        if( src == null )        {            return null;        }         int w = src.getWidth();        int h = src.getHeight();        int ww = watermark.getWidth();        int wh = watermark.getHeight();        //create the new blank bitmap        Bitmap newb = Bitmap.createBitmap( w, h, Config.ARGB_8888 );//创建一个新的和SRC长度宽度一样的位图        Canvas cv = new Canvas( newb );        //draw src into        cv.drawBitmap( src, 0, 0, null );//在 0，0坐标开始画入src        //draw watermark into        cv.drawBitmap( watermark, w - ww + 5, h - wh + 5, null );//在src的右下角画入水印        //save all clip        cv.save( Canvas.ALL_SAVE_FLAG );//保存        //store        cv.restore();//存储        return newb;    }   /** 重新编码Bitmap   *    * @param src   *          需要重新编码的Bitmap   *   * @param format   *          编码后的格式（目前只支持png和jpeg这两种格式）   *   * @param quality   *          重新生成后的bitmap的质量   *   * @return   *          返回重新生成后的bitmap   */ private static Bitmap codec(Bitmap src, Bitmap.CompressFormat format,                                    int quality) {            ByteArrayOutputStream os = new ByteArrayOutputStream();            src.compress(format, quality, os);                        byte[] array = os.toByteArray();            return BitmapFactory.decodeByteArray(array, 0, array.length);        }//Stream转换成Bytestatic byte[] streamToBytes(InputStream is) {      ByteArrayOutputStream os = new ByteArrayOutputStream(1024);      byte[] buffer = new byte[1024];      int len;      try {             while ((len = is.read(buffer)) >= 0) {             os.write(buffer, 0, len);             }          } catch (java.io.IOException e) {          }          return os.toByteArray();}//把View转换成Bitmap    /**     * 把一个View的对象转换成bitmap     */    static Bitmap getViewBitmap(View v) {            v.clearFocus();        v.setPressed(false);        //能画缓存就返回false        boolean willNotCache = v.willNotCacheDrawing();        v.setWillNotCacheDrawing(false);         int color = v.getDrawingCacheBackgroundColor();        v.setDrawingCacheBackgroundColor(0);        if (color != 0) {            v.destroyDrawingCache();        }        v.buildDrawingCache();        Bitmap cacheBitmap = v.getDrawingCache();        if (cacheBitmap == null) {            Log.e(TAG, "failed getViewBitmap(" + v + ")", new RuntimeException());            return null;        }        Bitmap bitmap = Bitmap.createBitmap(cacheBitmap);        // Restore the view        v.destroyDrawingCache();        v.setWillNotCacheDrawing(willNotCache);        v.setDrawingCacheBackgroundColor(color);        return bitmap;    }

读取raw资源文件中的mp3文件，然后通过音乐播放器播放：/** * 把mp3文件写入卡 *  * @param fileName *             输出的文件名（全路径） * @param context         *             context对象 */private void writeMP3ToSDcard(String fileName, Context context) {byte[] buffer = new byte[1024 * 8];int read;BufferedInputStream bin = new BufferedInputStream(context.getResources().openRawResource(R.raw.ring));try {BufferedOutputStream bout = new BufferedOutputStream(new FileOutputStream(fileName));while ((read = bin.read(buffer)) > -1) {bout.write(buffer, 0, read);}bout.flush();bout.close();bin.close();} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}Intent intent = new Intent();intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);intent.setAction(android.content.Intent.ACTION_VIEW);intent.setDataAndType(Uri.fromFile(newFile("XXXXmp3的文件全路径")),"audio/*");startActivity(intent);

绘制图像倒影

private void  _Init()   {     m_paint = new Paint(Paint.ANTI_ALIAS_FLAG);     LinearGradient lg = new LinearGradient(       0, 0, 0, m_nShadowH,        0xB0FFFFFF, 0x00000000,       Shader.TileMode.CLAMP);     m_paint.setShader(lg);     m_paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.MULTIPLY));   }     @Override protected void    onDraw(Canvas canvas)   {     super.onDraw(canvas);       int nX = 0;     int nY = 20;       _DrawNormalImg(canvas, nX, nY);     _DrawMirror(canvas, nX, nY);   }      private void  _DrawNormalImg(Canvas canvas, int nX, int nY)   {     canvas.save(Canvas.MATRIX_SAVE_FLAG);     canvas.translate(nX, nY);        m_dw.draw(canvas);     canvas.restore();   }     private void  _DrawMirror(Canvas canvas, int nX, int nY)   {     int nW = m_dw.getIntrinsicWidth();     int nH = m_dw.getIntrinsicHeight();       ///////////////////////////////////     //draw mirror image     canvas.save(Canvas.MATRIX_SAVE_FLAG);     canvas.scale(1.0f, -1.0f);     canvas.translate(nX, -(nY + nH * 2));     canvas.clipRect(0, nH, nW, nH - m_nShadowH);     m_dw.draw(canvas);     canvas.restore();       //////////////////////////////     //draw mask     canvas.save();     canvas.translate(nX, nY + nH);     canvas.drawRect(0, 0, nW, m_nShadowH, m_paint);     canvas.restore();   }  

Android 繪圖座標體系預設的原點在左上角，X 軸往右是越來越大的正值，而 Y 軸往下，則是越來越大的正值。要畫出垂直翻轉的圖片，其實也就是要垂直翻轉整個繪圖座標體系。在 Android 中，要如何做？答案就是 canvas.scale(1.0f, -1.0f)。很簡單吧，沒想到給 scale() 函式一個負值，就可以翻轉相對應的軸。
在 Photoshop 中，做鏡像特效的第二步是要對這翻轉的圖片，加個由灰到黑的漸層 mask。
在 Android 中，要畫漸層色，那就一定得用 LinearGradient 這個類別。至於要對背景圖加上個 mask，就請參考一下 Paint 的 setXfermode() 函式。_Init() 這個函式，就是負責生成一個由灰到黑漸層 mask 的 m_paint 物件。



http://blog.csdn.net/Android_Tutor/archive/2010/11/02/5981753.aspx

http://www.cnblogs.com/TerryBlog/archive/2012/01/08/2316482.html

android常用图片特效处理
http://www.eoeandroid.com/thread-170526-1-1.html

相机（Camera）实时滤镜效果
http://www.eoeandroid.com/thread-171528-1-1.html