Android Bitmap用法总结

Bitmap用法总结(转载自：http://blog.csdn.net/YUZHIBOYI/article/details/7638952#comments)

1、Drawable → Bitmap

 public static Bitmap drawableToBitmap(Drawable drawable) {  Bitmap bitmap = Bitmap  .createBitmap(  drawable.getIntrinsicWidth(),  drawable.getIntrinsicHeight(),  drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888  : Bitmap.Config.RGB_565);  Canvas canvas = new Canvas(bitmap);  // canvas.setBitmap(bitmap);  drawable.setBounds(0,0, drawable.getIntrinsicWidth(),  drawable.getIntrinsicHeight());  drawable.draw(canvas);  return bitmap;  } 

2、从资源中获取Bitmap

Resources res=getResources();Bitmap bmp=BitmapFactory.decodeResource(res, R.drawable.pic);

3、Bitmap → byte[]

 private byte[] Bitmap2Bytes(Bitmap bm){ByteArrayOutputStream baos = new ByteArrayOutputStream();bm.compress(Bitmap.CompressFormat.PNG, 100, baos);return baos.toByteArray();

4、byte[] → Bitmap

 private Bitmap Bytes2Bimap(byte[] b){if(b.length!=0){return BitmapFactory.decodeByteArray(b,0, b.length);}else {return null;}}

5、保存bitmap

 static boolean saveBitmap2file(Bitmap bmp,String filename){CompressFormat format= Bitmap.CompressFormat.JPEG;int quality = 100;OutputStream stream = null;try {stream = new FileOutputStream("/sdcard/" + filename);} catch (FileNotFoundException e) {// TODO Auto-generated catch block Generated by Foxit PDF Creator © Foxit Software http://www.foxitsoftware.com For evaluation only.e.printStackTrace();}return bmp.compress(format, quality, stream);}

6、将图片按自己的要求缩放

 // 图片源Bitmap bm = BitmapFactory.decodeStream(getResources().openRawResource(R.drawable.dog));// 获得图片的宽高int width = bm.getWidth();int height = bm.getHeight();// 设置想要的大小int newWidth = 320;int newHeight = 480;// 计算缩放比例float scaleWidth = ((float) newWidth) / width;float scaleHeight = ((float) newHeight) / height;// 取得想要缩放的matrix参数Matrix matrix = new Matrix();matrix.postScale(scaleWidth, scaleHeight);// 得到新的图片Bitmap newbm = Bitmap.createBitmap(bm, 0, 0, width, height, matrix,true);// 放在画布上canvas.drawBitmap(newbm, 0,0, paint);

   相关知识链接：http://www.eoeandroid.com/thread-3162-1-1.html

7、bitmap的用法小结

 BitmapFactory.Options option =new BitmapFactory.Options();option.inSampleSize = 2;//将图片设为原来宽高的1/2，防止内存溢出Bitmap bm = BitmapFactory.decodeFile("",option);//文件流URL url = new URL("");InputStream is = url.openStream();Bitmap bm = BitmapFactory.decodeStream(is);android:scaleType：android:scaleType是控制图片如何resized/moved来匹对ImageView的size。ImageView.ScaleType /android:scaleType值的意义区别：CENTER /center 按图片的原来size居中显示，当图片长/宽超过View的长/宽，则截取图片的居中部分显示CENTER_CROP / centerCrop 按比例扩大图片的size居中显示，使得图片长(宽)等于或大于View的长(宽)CENTER_INSIDE / centerInside 将图片的内容完整居中显示，通过按比例缩小或原来的size使得图片长/宽等于或小于View的长/宽Generated by Foxit PDF Creator © Foxit Softwarehttp://www.foxitsoftware.com For evaluation only.FIT_CENTER / fitCenter 把图片按比例扩大/缩小到View的宽度，居中显示FIT_END / fitEnd 把图片按比例扩大/缩小到View的宽度，显示在View的下部分位置FIT_START / fitStart 把图片按比例扩大/缩小到View的宽度，显示在View的上部分位置FIT_XY / fitXY 把图片 不按比例 扩大/缩小到View的大小显示MATRIX / matrix 用矩阵来绘制，动态缩小放大图片来显示。

8. 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;}

9. 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;// Generated by Foxit PDF Creator © Foxit Software http://www.foxitsoftware.com For evaluation only.}

10. 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;}

11. 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();Generated by Foxit PDF Creator © Foxit Softwarehttp://www.foxitsoftware.com For evaluation only.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 inpaint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));// Draw a rectangle using the paint with our linear gradientcanvas.drawRect(0, height, width, bitmapWithReflection.getHeight()+ reflectionGap, paint);return bitmapWithReflection;}}