Question

I’m in the process of developing an android game. I have an activity that has a custom class that extends the view and where everything is drawn. Everything works fine and I have implemented a way to draw levels and it looks good.

The problem that I have is that the levels are clearly too big for just 1 screen and re-designing them is not an option as it affects the user experience. The only solution that I see is making the screen scrollable so that you can move around the rendered stuff and zooming. What I’m looking for is double tapping anywhere to zoom in and out and scrolling to move around the map.

What I need help with is how to do this. I know how to detect that the user has scrolled or double tapped but I don’t know what I should do to actually zoom in and out and scroll (if a scroll is detected).

I have been looking around and saw some very simple tutorials but all of them deal with zooming in/out of an image which is not what I need. My level is rendered using many different bitmaps so I know I need to redraw all of them when updating the screen (zoom or scroll).

Is my case the same as having a single image. When it comes to scrolling I think what need to be done is calculating how much the screen is “moved” then update the and redraw the view bitmaps with the new scaled coordinates, is this correct? What about zooming?

Any help would be much appreciated. Thanks

Answer 1

Zooming should be easy once you have detected where you are currently at (zoom level i.e.)

image.setBounds((getWidth()/2)-zoomControler, (getHeight()/2)-zoomControler, (getWidth()/2)+zoomControler, (getHeight()/2)+zoomControler);

Something like that should help you zoom out/in on the image. When the zoom levels cross a certain level, you can consider swapping out an image that is more detailed that the one you are currently rendering.