滑輪控件的研究五、ViewConfiguration的簡單介紹

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/**
 * 包含了方法和標準的常量用來設置UI的超時、大小和距離
 */
public class ViewConfiguration {
    // 設定水平滾動條的寬度和垂直滾動條的高度，單位是像素px
    private static final int SCROLL_BAR_SIZE = 10;

    //定義滾動條逐漸消失的時間，單位是毫秒
    private static final int SCROLL_BAR_FADE_DURATION = 250;

    // 默認的滾動條多少秒之後消失，單位是毫秒
    private static final int SCROLL_BAR_DEFAULT_DELAY = 300;

    // 定義邊緣地方褪色的長度
    private static final int FADING_EDGE_LENGTH = 12;

    //定義子控件按下狀態的持續事件
    private static final int PRESSED_STATE_DURATION = 125;

    //定義一個按下狀態轉變成長按狀態的轉變時間
    private static final int LONG_PRESS_TIMEOUT = 500;

    //定義用戶在按住適當按鈕，彈出全局的對話框的持續時間
    private static final int GLOBAL_ACTIONS_KEY_TIMEOUT = 500;

    //定義一個touch事件中是點擊事件還是一個滑動事件所需的時間，如果用戶在這個時間之內滑動，那麼就認爲是一個點擊事件
    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.
     */
    //定義一個touch事件時候是一個點擊事件。如果用戶在這個時間內沒有完成這個點擊，那麼就認爲是一個點擊事件
    private static final int JUMP_TAP_TIMEOUT = 500;

    //定義雙擊事件的間隔時間
    private static final int DOUBLE_TAP_TIMEOUT = 300;

    //定義一個縮放控制反饋到用戶界面的時間
    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;

   //用來初始化fling的最小速度，單位是每秒多少像素
    private static final int MINIMUM_FLING_VELOCITY = 50;

    //用來初始化fling的最大速度，單位是每秒多少像素
    private static final int MAXIMUM_FLING_VELOCITY = 4000;

    //視圖繪圖緩存的最大尺寸，以字節表示。在ARGB888格式下，這個尺寸應至少等於屏幕的大小
    @Deprecated
    private static final int MAXIMUM_DRAWING_CACHE_SIZE = 320 * 480 * 4; // HVGA screen, ARGB8888

    //flings和scrolls摩擦力度大小的係數
    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;

}

轉自:http://blog.csdn.net/lonelyroamer/article/details/7568129