is it possible simplify my logic on dart?

Question

I used this logic for animation. Is it possible to simplify this logic?

SliverAppBar FlexibleSpaceBar

  void _positionListener() {
    final FlexibleSpaceBarSettings settings = context.dependOnInheritedWidgetOfExactType();
    _fontSize = getFontSize(settings.minExtent.toInt(), settings.maxExtent.toInt(), settings.currentExtent.toInt());
setState(() {});
  }

need to simplify below logic

 double getFontSize(int minExtent, int maxExtent, int currentExtent){
    double onePaddingExtent = (maxExtent - minExtent) / 31;

    if (currentExtent >= minExtent && currentExtent <= minExtent + (1 * onePaddingExtent))
      return 3.0;
    else if (currentExtent > minExtent + (1 * onePaddingExtent) && currentExtent <= minExtent + (2 * onePaddingExtent))
      return 2.9;
    else if (currentExtent > minExtent + (2 * onePaddingExtent) && currentExtent <= minExtent + (3 * onePaddingExtent))
      return 2.8;
    else if (currentExtent > minExtent + (3 * onePaddingExtent) && currentExtent <= minExtent + (4 * onePaddingExtent))
      return 2.7;
    else if (currentExtent > minExtent + (4 * onePaddingExtent) && currentExtent <= minExtent + (5 * onePaddingExtent))
      return 2.6;
    else if (currentExtent > minExtent + (5 * onePaddingExtent) && currentExtent <= minExtent + (6 * onePaddingExtent))
      return 2.5;
    else if (currentExtent > minExtent + (6 * onePaddingExtent) && currentExtent <= minExtent + (7 * onePaddingExtent))
      return 2.4;
    else if (currentExtent > minExtent + (7 * onePaddingExtent) && currentExtent <= minExtent + (8 * onePaddingExtent))
      return 2.3;
    else if (currentExtent > minExtent + (8 * onePaddingExtent) && currentExtent <= minExtent + (9 * onePaddingExtent))
      return 2.2;
    else if (currentExtent > minExtent + (9 * onePaddingExtent) && currentExtent <= minExtent + (10 * onePaddingExtent))
      return 2.1;
    else if (currentExtent > minExtent + (10 * onePaddingExtent) && currentExtent <= minExtent + (11 * onePaddingExtent))
      return 2.0;
    else if (currentExtent > minExtent + (11 * onePaddingExtent) && currentExtent <= minExtent + (12 * onePaddingExtent))
      return 1.9;
    else if (currentExtent > minExtent + (12 * onePaddingExtent) && currentExtent <= minExtent + (13 * onePaddingExtent))
      return 1.8;
    else if (currentExtent > minExtent + (13 * onePaddingExtent) && currentExtent <= minExtent + (14 * onePaddingExtent))
      return 1.7;
    else if (currentExtent > minExtent + (14 * onePaddingExtent) && currentExtent <= minExtent + (15 * onePaddingExtent))
      return 1.6;
    else if (currentExtent > minExtent + (15 * onePaddingExtent) && currentExtent <= minExtent + (16 * onePaddingExtent))
      return 1.5;
    else if (currentExtent > minExtent + (16 * onePaddingExtent) && currentExtent <= minExtent + (17 * onePaddingExtent))
      return 1.4;
    else if (currentExtent > minExtent + (17 * onePaddingExtent) && currentExtent <= minExtent + (18 * onePaddingExtent))
      return 1.3;
    else if (currentExtent > minExtent + (18 * onePaddingExtent) && currentExtent <= minExtent + (19 * onePaddingExtent))
      return 1.2;
    else if (currentExtent > minExtent + (19 * onePaddingExtent) && currentExtent <= minExtent + (20 * onePaddingExtent))
      return 1.0;
    else if (currentExtent > minExtent + (20 * onePaddingExtent) && currentExtent <= minExtent + (21 * onePaddingExtent))
      return 1;
    else if (currentExtent > minExtent + (21 * onePaddingExtent) && currentExtent <= minExtent + (22 * onePaddingExtent))
      return 0.9;
    else if (currentExtent > minExtent + (22 * onePaddingExtent) && currentExtent <= minExtent + (23 * onePaddingExtent))
      return 0.8;
    else if (currentExtent > minExtent + (23 * onePaddingExtent) && currentExtent <= minExtent + (24 * onePaddingExtent))
      return 0.7;
    else if (currentExtent > minExtent + (24 * onePaddingExtent) && currentExtent <= minExtent + (25 * onePaddingExtent))
      return 0.6;
    else if (currentExtent > minExtent + (25 * onePaddingExtent) && currentExtent <= minExtent + (26 * onePaddingExtent))
      return 0.5;
    else if (currentExtent > minExtent + (26 * onePaddingExtent) && currentExtent <= minExtent + (27 * onePaddingExtent))
      return 0.4;
    else if (currentExtent > minExtent + (27 * onePaddingExtent) && currentExtent <= minExtent + (28 * onePaddingExtent))
      return 0.3;
    else if (currentExtent > minExtent + (28 * onePaddingExtent) && currentExtent <= minExtent + (29 * onePaddingExtent))
      return 0.2;
    else if (currentExtent > minExtent + (29 * onePaddingExtent) && currentExtent <= minExtent + (30 * onePaddingExtent))
      return 0.1;
    else if (currentExtent > minExtent + (30 * onePaddingExtent) && currentExtent <= minExtent + (31 * onePaddingExtent))
      return 0;
    else
      return 0;
  }

I tried this way, but not working

  double getFontSize(int minExtent, int maxExtent, int currentExtent) {
    double onePaddingExtent = (maxExtent - minExtent) / 31;
    
    var baseValue = (currentExtent + minExtent) / onePaddingExtent ;
    var upperBaseValue = baseValue.round();
    var lowerBaseValue = baseValue.floor();


    var result = 30 - Math.min(upperBaseValue, lowerBaseValue);

    return Math.max(result, 0);
  }

@mezoni normal logic. it's working fine. I just need to simplify (short logic) — BIS Tech, Jan 20 '21 at 17:34

score 2 · Answer 1 · answered Jan 20 '21 at 16:56

2

Maybe you can try this

if (currentExtent >= minExtent && currentExtent <= minExtent + (1 * onePaddingExtent)) return 3.0;
else for (int i = 1; i <= 30; ++ i) if ((currentExtent > minExtent + (i * onePaddingExtent)) && (currentExtent <= minExtent + ((i + 1) * onePaddingExtent))) return 3.0 - (i / 10);

answered Jan 20 '21 at 16:56

dm_tr

4,265
1
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okay, I will try, but for loop not working to my scenario. because I'm using `flexiblespacebar`. same as `scrollController` – BIS Tech Jan 20 '21 at 17:15
Replace it with just your `if..else` section – dm_tr Jan 20 '21 at 17:18
`return 3.0 - (i / 10)` this part is not the correct value right compare with minelogic? – BIS Tech Jan 20 '21 at 17:30
`3.0 - 0.1 | 3.0 - 0.2 | 3.0 - 0.3 .... 3.0 - 2.9 | 3.0 - 3.0` are not your values ? – dm_tr Jan 21 '21 at 07:34

jamesdlin · Accepted Answer · 2021-01-20T20:20:59.313

First we can see that there's a pattern in your cases and simplify it with a loop:

 double getFontSize(int minExtent, int maxExtent, int currentExtent) {
    double onePaddingExtent = (maxExtent - minExtent) / 31;

    for (var i = 0; i < 31; i += 1) {
      if (currentExtent >= minExtent + (i * onePaddingExtent) &&
          currentExtent <= minExtent + (i + 1) * onePaddingExtent) {
        return 3.0 - i / 10;
    }  
    return 0;
  }
}

(In your original code, your first case is slightly different because it checks for a closed interval [minimum, maximum], whereas all of subsequent cases check for a half-open interval of (minimum, maximum]. However, since the loop will check the cases in order, it doesn't matter if we use a closed interval for all cases: a value that's exactly a minimum/maximum will be satisfied by only the first applicable case anyway.)

From there, we can algebraically rearrange the inequalities and see that the if condition is equivalent to:

if ((currentExtent - minExtent) / onePaddingExtent >= i &&
    (currentExtent - minExtent) / onePaddingExtent <= (i + 1))

which means that (currentExtent - minExtent) / onePaddingExtent lies in the range [i, i + 1] for some integer i. In other words, i is the greatest integer that is less than or equal to (currentExtent - minExtent) / onePaddingExtent. Therefore, instead of iterating to find i, we can compute i directly without a loop:

double getFontSize(int minExtent, int maxExtent, int currentExtent) {
  double onePaddingExtent = (maxExtent - minExtent) / 31;
  var i = ((currentExtent - minExtent) / onePaddingExtent).floor();
  if (i >= 0 && i < 31) {
    return 3.0 - i / 10;
  }
  return 0;
}

Note that the above simplifications can return very slightly different values than your original code (e.g. 0.9 vs 0.8999999999999999), but that's an artifact of performing additional floating-point operations. (Don't fool yourself; floating-point values, even literals, aren't exact.)

is it possible simplify my logic on dart?

2 Answers2