图像显示控件PhotoView

Features Out of the box zooming, using multi-touch and double-tap. Scrolling, with smooth scrolling fling. Works perfectly when using used in a scrolling parent (such as ViewPager). Allows the application to be notified when the displayed Matrix has changed. Useful for when you need to update your UI based on the current zoom/scroll position. Allows the application to be notified when the user taps on the Photo. 实现图片浏览功能，支持pinch（捏合）手势或者点击放大缩小。支持在ViewPager中翻页浏览图片 https://github.com/chrisbanes/PhotoView