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();