根据路径获取图片，缩放图片

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记录几个常用的图片相关操作方法；

////根据路径获取图片，指定尺寸进行压缩private Bitmap decodeThumbBitmapForFile(String path, int w, int h){BitmapFactory.Options opts = new BitmapFactory.Options();opts.inJustDecodeBounds = true;//opts.inPreferredConfig = Bitmap.Config.RGB_565; //如果不要求透明度可用此模式，更省内存//获取图片尺寸BitmapFactory.decodeFile(path, opts);int width = opts.outWidth;int height = opts.outHeight;float scaleWidth = 0.f, scaleHeight = 0.f;if (width > w || height > h) {//计算比例scaleWidth = ((float) width) / w;scaleHeight = ((float) height) / h;}opts.inJustDecodeBounds = false;//float scale = Math.max(scaleWidth, scaleHeight); //取较大或小数Math.min(,);//图片压缩比例，此数越大图片越小；（如为2,长宽都为原来的1/2,即图片为原图1/4份）opts.inSampleSize = (int)scale; //取整Math.ceil(scale)////弱引用，更易被系统回收WeakReference<Bitmap> weak = new WeakReference<Bitmap>(BitmapFactory.decodeFile(path, opts));return Bitmap.createScaledBitmap(weak.get(), w, h, true);}

//////////另一种方式读取图片FileInputStream public static Bitmap loadFromSdCard(String filePath) {File file = new File(filePath);Bitmap bmp = null;try {BitmapFactory.Options opts = new BitmapFactory.Options();opts.inJustDecodeBounds = false;opts.inPreferredConfig = Bitmap.Config.RGB_565;opts.inSampleSize = 2;FileInputStream fis = new FileInputStream(file);bmp = BitmapFactory.decodeStream(fis, null, opts);if(fis!=null){ try {fis.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}if (bmp != null) {return bmp;}} catch (FileNotFoundException e) {e.printStackTrace();}return null;}

////将图片进行缩放public static Bitmap scaleBitmap(Bitmap bmp, float newWidth, float newHeight) {if (bmp != null) {   int w= bm.getWidth();     int h = bm.getHeight();     // 计算比例     float scaleWidth = ((float) newWidth) / w;     float scaleHeight = ((float) newHeight) / h;         Matrix matrix = new Matrix();     matrix.postScale(scaleWidth, scaleHeight);if (scaleWidth== 1.0f && scaleHeight== 1.0f) {return bmp;}Bitmap newbm = Bitmap.createBitmap(bmp, 0, 0, w,h, matrix, true);//return newbm;}return null;}

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