1     /**  2      * 包含了方法和标准的常量用来设置UI的超时、大小和距离  3      */   4     public class ViewConfiguration {   5         // 设定水平滚动条的宽度和垂直滚动条的高度，单位是像素px   6         private static final int SCROLL_BAR_SIZE = 10;   7        8         //定义滚动条逐渐消失的时间，单位是毫秒   9         private static final int SCROLL_BAR_FADE_DURATION = 250;  10       11         // 默认的滚动条多少秒之后消失，单位是毫秒  12         private static final int SCROLL_BAR_DEFAULT_DELAY = 300;  13       14         // 定义边缘地方褪色的长度  15         private static final int FADING_EDGE_LENGTH = 12;  16       17         //定义子控件按下状态的持续事件  18         private static final int PRESSED_STATE_DURATION = 125;  19           20         //定义一个按下状态转变成长按状态的转变时间  21         private static final int LONG_PRESS_TIMEOUT = 500;  22           23         //定义用户在按住适当按钮，弹出全局的对话框的持续时间  24         private static final int GLOBAL_ACTIONS_KEY_TIMEOUT = 500;  25           26         //定义一个touch事件中是点击事件还是一个滑动事件所需的时间，如果用户在这个时间之内滑动，那么就认为是一个点击事件  27         private static final int TAP_TIMEOUT = 115;  28           29         /** 30          * Defines the duration in milliseconds we will wait to see if a touch event  31          * is a jump tap. If the user does not complete the jump tap within this interval, it is 32          * considered to be a tap.  33          */  34         //定义一个touch事件时候是一个点击事件。如果用户在这个时间内没有完成这个点击，那么就认为是一个点击事件  35         private static final int JUMP_TAP_TIMEOUT = 500;  36       37         //定义双击事件的间隔时间  38         private static final int DOUBLE_TAP_TIMEOUT = 300;  39           40         //定义一个缩放控制反馈到用户界面的时间  41         private static final int ZOOM_CONTROLS_TIMEOUT = 3000;  42       43         /** 44          * Inset in pixels to look for touchable content when the user touches the edge of the screen 45          */  46         private static final int EDGE_SLOP = 12;  47           48         /** 49          * Distance a touch can wander before we think the user is scrolling in pixels 50          */  51         private static final int TOUCH_SLOP = 16;  52           53         /** 54          * Distance a touch can wander before we think the user is attempting a paged scroll 55          * (in dips) 56          */  57         private static final int PAGING_TOUCH_SLOP = TOUCH_SLOP * 2;  58           59         /** 60          * Distance between the first touch and second touch to still be considered a double tap 61          */  62         private static final int DOUBLE_TAP_SLOP = 100;  63           64         /** 65          * Distance a touch needs to be outside of a window‘s bounds for it to 66          * count as outside for purposes of dismissing the window. 67          */  68         private static final int WINDOW_TOUCH_SLOP = 16;  69       70        //用来初始化fling的最小速度，单位是每秒多少像素  71         private static final int MINIMUM_FLING_VELOCITY = 50;  72           73         //用来初始化fling的最大速度，单位是每秒多少像素  74         private static final int MAXIMUM_FLING_VELOCITY = 4000;  75       76         //视图绘图缓存的最大尺寸，以字节表示。在ARGB888格式下，这个尺寸应至少等于屏幕的大小  77         @Deprecated  78         private static final int MAXIMUM_DRAWING_CACHE_SIZE = 320 * 480 * 4; // HVGA screen, ARGB8888  79       80         //flings和scrolls摩擦力度大小的系数  81         private static float SCROLL_FRICTION = 0.015f;  82       83         /** 84          * Max distance to over scroll for edge effects 85          */  86         private static final int OVERSCROLL_DISTANCE = 0;  87       88         /** 89          * Max distance to over fling for edge effects 90          */  91         private static final int OVERFLING_DISTANCE = 4;  92       93     }  

1 ViewConfiguration vc = ViewConfiguration.get(context);2         mSlop = vc.getScaledTouchSlop();3         mMinFlingVelocity = vc.getMinimumFlingVelocity();4         mMinFlingVelocity = vc.getMaximumFlingVelocity();