android中图片缩放方法有三种：1，bitmapFactory；2，bitmap+metrix；3，thumbUtil
方法一：bitmapFactory：
public static Bitmap resizeBitmapByFactory(String path, int w, int h) {BitmapFactory.Options option = new BitmapFactory.Options();option.inJustDecodeBounds = true;Bitmap bitmap = BitmapFactory.decodeFile(path, option);int outWidth = option.outWidth;int outHeight = option.outHeight;option.inDither = false;option.inPreferredConfig = Bitmap.Config.ARGB_8888;if (outWidth != 0 && outHeight != 0 && w != 0 && h != 0) {int sampleSize = (outWidth / w + outHeight / h) / 2;option.inSampleSize = sampleSize;}option.inJustDecodeBounds = false;return BitmapFactory.decodeFile(path, option);}
方法二：bitmap+metrix
public static Bitmap resizeBitmapByMetrix(Bitmap bitmap, int w, int h) {Bitmap BitmapOrg = bitmap;int width = BitmapOrg.getWidth();int height = BitmapOrg.getHeight();int newWidth = w;int newHeight = h;float scaleWidth = ((float) newWidth) / width;float scaleHeight = ((float) newHeight) / height;Matrix matrix = new Matrix();matrix.postScale(scaleWidth, scaleHeight);// if you want to rotate the Bitmap// matrix.postRotate(45);Bitmap resizedBitmap = Bitmap.createBitmap(BitmapOrg, 0, 0, width,height, matrix, true);return resizedBitmap;}
方法三，使用系统自带的thumbutil：
public static Bitmap resizeBitmapByUtil(Bitmap bitmap, int w, int h) {return ThumbnailUtils.extractThumbnail(bitmap, w, h);}
三个方法消耗的时间为：72，9，13不过怀疑方法一消耗的时间有可能是由于从文件中加载图片所致。这点待定
二、实现图片的圆角效果
public static Bitmap toRoundCornerBitmap(Bitmap bitmap, int cornerPixel) {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);final float roundPx = cornerPixel;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;}
三、实现图片缩放，背景为圆角图片，则这个背景可以用图形资源文件来实现。
<?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle"><gradient android:angle="90" android:endColor="#00000000" android:startColor="#00000000" /> <corners android:bottomLeftRadius="12dp" android:bottomRightRadius="12dp" android:topLeftRadius="12dp" android:topRightRadius="12dp" /> <stroke android:width="1dip" android:color="#eee" /> <solidandroid:color="#000"/><padding android:top="5dp"android:bottom="5dp"/></shape>
