Android Matrix.postSacle () function for the interpretation, seeking advice, urgent! ! ! ! !

            
Recently made an image scaling of Design graduate, you seek guidance about the great God, here is my problem:

I understand the image scaling is such a matrix for each picture can be seen as a matrix of pixels, there are many, when
When an enlarged image is of course the length and width of the matrix to be expanded, the original image pixel matrix is ​​clearly insufficient filling enlarged,
This requires a series of algorithms used in the difference of the new matrix pixel interpolation.
So the question arises, and now the phone is 5 million pixels or more frequently, if you really want to put this image
Large, then no matter how simple interpolation algorithm, the calculation should be scary it, (because I like the picture of the program to operate directly
Card out), but why the album comes with Android system procedures, photographs taken can be quickly zoom it? Is it because it does
No use for pixel interpolation algorithm, but directly on the matrix operation? Is it because more than enough pixels,
on such a small screen phoneDo not need pixel interpolation it? If yes, then the system has its own procedures for how image matrix transform it? If not,
Please tell me what system is used?

I found a lot of programs in the online examples of Android image scaling, there is such a code: Matrix.postSacle (),
Enabling the rapid scaling of the picture, I want to know, this function matrix of the picture actually done what action? This function does not require internal
Pixel interpolation it?