How to Screen Zoom in Mac Yosemite OS X how to scroll zoom

enable screen zoom in Mac Yosemite OSX, mavericks osx. Macbook pro, iMac, macbook air, macbook, macbook retina display, macbook retina display 2, mac pro, iMac retina 5k display , mac mini,apple laptop. zoom content on the screen, how to turn on and turn zoom off, mac screen zoom, zoom anything anywhere on mac. yosemite , zoom pressing control and scrolling mouse , magic mouse