How can I get zoom functionality for images?

Question

Is there a common way to show a big image and enable the user to zoom in and out and pan the image?

Until now I found two ways:

1. overwriting ImageView,

Answer 1

I used a WebView and loaded the image from the memory via

webview.loadUrl("file://...")

The WebView handles all the panning zooming and scrolling. If you use wrap_content the webview won't be bigger then the image and no white areas are shown. The WebView is the better ImageView ;)