Android - Bitmap 相关
If set to true, the decoder will return null (no bitmap), but the out… fields will still be set, allowing the caller to query the bitmap without having to allocate the memory for its pixels.
If set to a value > 1, requests the decoder to subsample the original image, returning a smaller image to save memory. The sample size is the number of pixels in either dimension that correspond to a single pixel in the decoded bitmap. For example, inSampleSize == 4 returns an image that is 1/4 the width/height of the original, and 1/16 the number of pixels. Any value <= 1 is treated the same as 1. Note: the decoder uses a final value based on powers of 2, any other value will be rounded down to the nearest power of 2.