android Bitmap用法总结.pdf

android Bitmap用法总结 Normal 0 7.8 磅 0 2 false false false MicrosoftInternetExplorer4 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(); press(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 For evaluation only. e.printStackTrace(); } return press(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：