I am trying to make an app whereby a picture will be shown, there're a few objects that user needs to identify (i.e. a cup), by touching the cup in the picture on the screen, a circle will be drawn if it's valid.
So far, I have a surfaceview with a bitmap as drawable to be displayed full screen, and upon touching the screen, a circle will be drawn to the view.
I could only think of getting the coordinate of the cup manually in the picture(hardcoded), and check it against the coordinate from touch event.getX() and event.getY(). But this would not work as screen resolution changes.
What is a better way in doing so? It's like I'm trying to find a way to precisely allow touch on certain areas which I've defined in my app.
You can store the coords as you were suggesting but adjust them based on the size of the SurfaceView vs. the size of the BitmapDrawable. For example, if you know a given area is 100px from the left, you could take your scale as surfaceView.getWidth() / bitmapDrawable.getIntrinsicWidth(). Multiply your scale times your value (100px) to get the final position. If you're keeping the same aspect ratio on the image, you need to get your scale from the larger of the two (width vs. height) and use that same scale for height and width.