图片的等比缩放

	    public static Bitmap createScaledBitmap(Bitmap unscaledBitmap, int dstWidth, int dstHeight) {  

			   Rect srcRect = calculateSrcRect(unscaledBitmap.getWidth(), unscaledBitmap.getHeight(), dstWidth, dstHeight);  

			  Rect dstRect = calculateDstRect(unscaledBitmap.getWidth(), unscaledBitmap.getHeight(), dstWidth, dstHeight);  

			   Bitmap scaledBitmap = Bitmap.createBitmap(dstRect.width(), dstRect.height(), Config.ARGB_8888);  

			   Canvas canvas = new Canvas(scaledBitmap);  

			   canvas.drawBitmap(unscaledBitmap, srcRect, dstRect, new Paint(Paint.FILTER_BITMAP_FLAG));return scaledBitmap;  

			   } 


		
		
		
		private static Rect calculateSrcRect(int srcWidth, int srcHeight, int dstWidth, int dstHeight) {
			    final float srcAspect = (float)((float)srcWidth / (float)srcHeight);
			    final float dstAspect = (float)((float)dstWidth / (float)dstHeight);
			    if (srcAspect > dstAspect) {
			      final int srcRectWidth = (int)(srcHeight * dstAspect);
			      final int srcRectLeft = (srcWidth - srcRectWidth) / 2;
			      return new Rect(srcRectLeft, 0, srcRectLeft + srcRectWidth, srcHeight);
			    } else {
			      final int srcRectHeight = (int)(srcWidth / dstAspect);
			      final int scrRectTop = (int)(srcHeight - srcRectHeight) / 2;
			      return new Rect(0, scrRectTop, srcWidth, scrRectTop + srcRectHeight);
			    }
			}
			private static Rect calculateDstRect(int srcWidth, int srcHeight, int dstWidth, int dstHeight) {
			    final float srcAspect = (float)srcWidth / (float)srcHeight;
			    final float dstAspect = (float)dstWidth / (float)dstHeight;
			    if (srcAspect > dstAspect) {
			      return new Rect(0, 0, dstWidth, (int)(dstWidth / srcAspect));
			    } else {
			      return new Rect(0, 0, (int)(dstHeight * srcAspect), dstHeight);
			    }
			}

			
			private static Bitmap decodeFile(String pathName, int dstWidth, int dstHeight) {
				 Bitmap unscaledBitmap = null;
				if(dstWidth > 0){
					Options options = new Options();
					options.inJustDecodeBounds = true;
					BitmapFactory.decodeFile(pathName, options);
					options.inJustDecodeBounds = false;
					options.inSampleSize = calculateSampleSize(options.outWidth, options.outHeight, dstWidth, dstHeight);
					unscaledBitmap = BitmapFactory.decodeFile(pathName, options);
				}else{
					unscaledBitmap = BitmapFactory.decodeFile(pathName);
				}
				  return unscaledBitmap;
				}
				public static int calculateSampleSize(int srcWidth, int srcHeight, int dstWidth, int dstHeight) {
				    final float srcAspect = (float)srcWidth / (float)srcHeight;
				    final float dstAspect = (float)dstWidth / (float)dstHeight;
				    if (srcAspect > dstAspect) {
				      return srcWidth / dstWidth;
				    } else {
				      return srcHeight / dstHeight;
				    }
				}

调用如下：

Bitmap baseBitmap = decodeFile(picName,width,height);
Bitmap bitmap = createScaledBitmap(bitmap,width,height);