related question here on stackoverflow.
IF your image is downloaded from the internet, .getIntrinsicWidth()
and .getIntrinsicHeight()
indeed give you the "real" width and height, respectively of the image.
It's called intrinsic, because it depends ONLY on the image and on nothing else (such as your phone).
Alas, what you get is NOT intrinsic in all circumstances - it DOES depend things other than the image, unfortunately.
Here is where you get a wrong (namely, non-intrinsic) result. Let's say you are using the default launcher icon, then
Log.i("", "ic_launcher intrinsic width " + getResources().getDrawable(R.drawable.ic_launcher).getIntrinsicWidth());
will tell you the width (in pixels) of the launcher icon. But of which one? - you have several of them, one in drawable-xhdpi folder, one in drawable-hdpi folder, etc. Well, if your device is, say, xhdpi, it gives you 96, which is indeed the pixel-width of the version of the launcher icon residing in the drawable-xhdpi folder. Now, delete the icon in the drawable-xhdpi folder, and run again (still using an xhdpi device (real or emulated)). The image that will be used will be from drawable-hdpi folder, because that's "closest" to the xhdpi version. That icon has a pixel width of 72. But above code WILL STILL GIVE YOU 96!!!
That is clearly NOT "intrinsic" (in the proper sense of the word), as it does not depend only on the image used.
So if you are as lazy as I am, and are therefore not generating 4 versions of each resource icon/image (but instead using only 1 or 2, and scaling them by hand), you have to beware the mentioned androidal misnomer.