public static int calculateInSampleSize(BitmapFactory.Options options,
int reqWidth, int reqHeight) {
// Raw height and width of p_w_picpath
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
// Calculate ratios of height and width to requested height and
// width
final int heightRatio = Math.round((float) height
/ (float) reqHeight);
final int widthRatio = Math.round((float) width / (float) reqWidth);
// Choose the smallest ratio as inSampleSize value, this will
// guarantee
// a final p_w_picpath with both dimensions larger than or equal to the
// requested height and width.
inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
}
return inSampleSize;
}
public static Bitmap decodeSampledBitmapFromResource(Resources res,
int resId, int reqWidth, int reqHeight) {
// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true; //当设置inJustDecodeBounds为true时map为null设置了options高度，宽度和图片类型
BitmapFactory.decodeResource(res, resId, options);
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, reqWidth,
reqHeight);//获取图片本来大小宽高的1/inSampleSize像素的1/(inSmapleSize*inSampleSize)
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
return BitmapFactory.decodeResource(res, resId, options);
}
