Welcome to this first Android tutorial on how to make your own one finger zoom control like the one found in the Camera and Album applications in the Sony
F. Kargl, S. Geßler, and F. Flerlage. Ubiquitous Computing Systems, volume 4836 of Lecture Notes in Computer Science, Springer Berlin / Heidelberg, 10.1007/978-3-540-76772-5_9.(2010)