Android实现图片滚动控件.docxVIP

实现原理其实还是之前那篇文章Android滑动菜单特效实现，仿人人客户端侧滑效果，史上最简单的侧滑实现??，算是以那个原理为基础的另外一个变种。正所谓一通百通，真正掌握一种方法之后，就可以使用这个方法变换出各种不通的效果。今天仍然还是实现一个自定义控件，然后我们在任意Activity的布局文件中引用一下，即可实现图片滚动器的效果。在Eclipse中新建一个Android项目，项目名就叫做SlidingViewSwitcher。新建一个类，名叫SlidingSwitcherView，这个类是继承自RelativeLayout的，并且实现了OnTouchListener接口，具体代码如下：[java]?view plaincopypublic?class?SlidingSwitcherView?extends?RelativeLayout?implements?OnTouchListener?{????????/**??????*?让菜单滚动，手指滑动需要达到的速度。??????*/??????public?static?final?int?SNAP_VELOCITY?=?200;????????/**??????*?SlidingSwitcherView的宽度。??????*/??????private?int?switcherViewWidth;????????/**??????*?当前显示的元素的下标。??????*/??????private?int?currentItemIndex;????????/**??????*?菜单中包含的元素总数。??????*/??????private?int?itemsCount;????????/**??????*?各个元素的偏移边界值。??????*/??????private?int[]?borders;????????/**??????*?最多可以滑动到的左边缘。值由菜单中包含的元素总数来定，marginLeft到达此值之后，不能再减少。??????*???????*/??????private?int?leftEdge?=?0;????????/**??????*?最多可以滑动到的右边缘。值恒为0，marginLeft到达此值之后，不能再增加。??????*/??????private?int?rightEdge?=?0;????????/**??????*?记录手指按下时的横坐标。??????*/??????private?float?xDown;????????/**??????*?记录手指移动时的横坐标。??????*/??????private?float?xMove;????????/**??????*?记录手机抬起时的横坐标。??????*/??????private?float?xUp;????????/**??????*?菜单布局。??????*/??????private?LinearLayout?itemsLayout;????????/**??????*?标签布局。??????*/??????private?LinearLayout?dotsLayout;????????/**??????*?菜单中的第一个元素。??????*/??????private?View?firstItem;????????/**??????*?菜单中第一个元素的布局，用于改变leftMargin的值，来决定当前显示的哪一个元素。??????*/??????private?MarginLayoutParams?firstItemParams;????????/**??????*?用于计算手指滑动的速度。??????*/??????private?VelocityTracker?mVelocityTracker;????????/**??????*?重写SlidingSwitcherView的构造函数，用于允许在XML中引用当前的自定义布局。??????*???????*?@param?context??????*?@param?attrs??????*/??????public?SlidingSwitcherView(Context?context,?AttributeSet?attrs)?{??????????super(context,?attrs);??????}????????/**??????*?滚动到下一个元素。??????*/??????public?void?scrollToNext()?{??????????new?ScrollTask().execute(-20);??????}????????/**??????*?滚动到上一个元素。??????*/?????