How to find the co-ordinates of the transparent area of an .png image

In my application I use an image . I made some po开发者_如何学运维rtion of the image transparent. Now How can I find the co-ordinates of the transparent portion of the image so that I am able to find the actual area of the non-transparent area.

I don't know the android SDK, but I doubt it has image manipulaiton built in. so using what ever language you are in, you need to open the image as data. Hopefully you can use an image library that will perform things like getting the size of the image. This will let you access the raw pixel data, which you can then check though till you find a pixel whos transparency is not equal to zero.

finding it in the rows is fairly easy, but the columns will take a bit more work. Remember that pixel data will be accessed as an array of length width * height in pixels.