android.view.ViewConfiguration

源码地址:http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/4.2_r1/android/view/ViewConfiguration.java?av=f

 

/** 
* 包含了方法和标准的常量用来设置UI的超时、大小和距离 
*/ 
public class ViewConfiguration { 
    // 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 
    private static final int SCROLL_BAR_SIZE = 10; 

    //定义滚动条逐渐消失的时间，单位是毫秒 
    private static final int SCROLL_BAR_FADE_DURATION = 250; 

    // 默认的滚动条多少秒之后消失，单位是毫秒 
    private static final int SCROLL_BAR_DEFAULT_DELAY = 300; 

    // 定义边缘地方褪色的长度 
    private static final int FADING_EDGE_LENGTH = 12; 

    //定义子控件按下状态的持续事件 
    private static final int PRESSED_STATE_DURATION = 125; 
    
    //定义一个按下状态转变成长按状态的转变时间 
    private static final int LONG_PRESS_TIMEOUT = 500; 
    
    //定义用户在按住适当按钮，弹出全局的对话框的持续时间 
    private static final int GLOBAL_ACTIONS_KEY_TIMEOUT = 500; 
    
    //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 
    private static final int TAP_TIMEOUT = 115; 
    
    /** 
     * Defines the duration in milliseconds we will wait to see if a touch event 
     * is a jump tap. If the user does not complete the jump tap within this interval, it is 
     * considered to be a tap. 
     */ 
    //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 
    private static final int JUMP_TAP_TIMEOUT = 500; 

    //定义双击事件的间隔时间 
    private static final int DOUBLE_TAP_TIMEOUT = 300; 
    
    //定义一个缩放控制反馈到用户界面的时间 
    private static final int ZOOM_CONTROLS_TIMEOUT = 3000; 

    /** 
     * Inset in pixels to look for touchable content when the user touches the edge of the screen 
     */ 
    private static final int EDGE_SLOP = 12; 
    
    /** 
     * Distance a touch can wander before we think the user is scrolling in pixels 
     */ 
    private static final int TOUCH_SLOP = 16; 
    
    /** 
     * Distance a touch can wander before we think the user is attempting a paged scroll 
     * (in dips) 
     */ 
    private static final int PAGING_TOUCH_SLOP = TOUCH_SLOP * 2; 
    
    /** 
     * Distance between the first touch and second touch to still be considered a double tap 
     */ 
    private static final int DOUBLE_TAP_SLOP = 100; 
    
    /** 
     * Distance a touch needs to be outside of a window's bounds for it to 
     * count as outside for purposes of dismissing the window. 
     */ 
    private static final int WINDOW_TOUCH_SLOP = 16; 

   //用来初始化fling的最小速度，单位是每秒多少像素 
    private static final int MINIMUM_FLING_VELOCITY = 50; 
    
    //用来初始化fling的最大速度，单位是每秒多少像素 
    private static final int MAXIMUM_FLING_VELOCITY = 4000; 

    //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 
    @Deprecated 
    private static final int MAXIMUM_DRAWING_CACHE_SIZE = 320 * 480 * 4; // HVGA screen, ARGB8888 

    //flings和scrolls摩擦力度大小的系数 
    private static float SCROLL_FRICTION = 0.015f; 

    /** 
     * Max distance to over scroll for edge effects 
     */ 
    private static final int OVERSCROLL_DISTANCE = 0; 

    /** 
     * Max distance to over fling for edge effects 
     */ 
    private static final int OVERFLING_DISTANCE = 4; 

}