Statusbar height, navibar height, screen valid rect ...

1. public static int getActionBarHeight(Context cxt) {
     int[] abSzAttr;
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
       abSzAttr = new int[] { android.R.attr.actionBarSize };
     } else {
       abSzAttr = new int[] { R.attr.actionBarSize };
     }
     TypedArray a = cxt.obtainStyledAttributes(abSzAttr);
     return a.getDimensionPixelSize(0, -1);
   }
   
   
   public static void setStatusBarColor(Activity activity, int color) {
     Window window = activity.getWindow();
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
       window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
     }
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
       window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
     }
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
       window.setStatusBarColor(color);
     }
   }
   
   public static int getNavigationBarHeight(Context cxt) {
     boolean hasMenuKey = ViewConfiguration.get(cxt)
                                           .hasPermanentMenuKey();
     boolean hasBackKey = KeyCharacterMap.deviceHasKey(KeyEvent.KEYCODE_BACK);
     int navigationBarHeight = 0;
     if (!hasMenuKey && !hasBackKey) {
       final Resources resources = cxt.getResources();
       int resourceId = resources.getIdentifier("navigation_bar_height", "dimen", "android");
       if (resourceId > 0) {
         navigationBarHeight = resources.getDimensionPixelSize(resourceId);
       }
     }
     return navigationBarHeight;
   }
   
   public static int getStatusBarHeight(Context cxt) {
     int result = 0;
     final Resources resources = cxt.getResources();
     int resourceId = resources.getIdentifier("status_bar_height", "dimen", "android");
     if (resourceId > 0) {
       result = resources.getDimensionPixelSize(resourceId);
     }
     return result;
   }
   
   public static int getScreenVisibleHeight(Activity cxt) {
     Window window = cxt.getWindow();
     Rect rect = new Rect();
     window.getDecorView()
           .getWindowVisibleDisplayFrame(rect);
     int height = rect.height();
   
     if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
       height -= getStatusBarHeight(cxt);
     }
     return height;
   }