/// <summary>
/// Counts up the ForegroundColor from each entry in _rowResults, then
/// combines similar colors to allow for things like antialiasing.
/// Candidate colors are evaluated, beginning at the highest contrast
/// from backgroundColor, until we find a candidate that seems to occur
/// frequently enough that we accept it as the foreground color.
/// </summary>
private ColorVoteInfo GetForegroundInfo(Color backgroundColor)
{
CountMap <Color> simpleForegroundColorBallots = new CountMap <Color>();
_rowResults.ForEach(r =>
{
Color foregroundColor = r.ForegroundColor;
Color testBackgroundColor = r.BackgroundColor;
if (foregroundColor != null && backgroundColor.Equals(testBackgroundColor))
{
simpleForegroundColorBallots.Increment(r.ForegroundColor, r.TransitionCount);
}
});
if (!simpleForegroundColorBallots.Any())
{
return(null);
}
var simpleForegroundBallotsSortedByContrast = simpleForegroundColorBallots.OrderByDescending(x =>
{
ColorPair cp = new ColorPair(backgroundColor, x.Key);
return(cp.ColorContrast());
});
CountMap <Color> aggregatedForegroundColorBallots = new CountMap <Color>();
foreach (var pair in simpleForegroundBallotsSortedByContrast)
{
// Remember counts so we can add them after we iterate the entire list
CountMap <Color> rememberedCounts = new CountMap <Color>();
foreach (var aggregateForegroundColorBallot in aggregatedForegroundColorBallots)
{
if (aggregateForegroundColorBallot.Key.IsSimilarColor(pair.Key))
{
rememberedCounts
.Increment(aggregateForegroundColorBallot.Key, pair.Value);
}
}
foreach (var countToAdd in rememberedCounts)
{
aggregatedForegroundColorBallots
.Increment(countToAdd.Key, countToAdd.Value);
}
aggregatedForegroundColorBallots.Increment(pair.Key, pair.Value);
}
var sortedForegroundColorBallots = aggregatedForegroundColorBallots
.OrderByDescending(x => x.Value);
return(BuildColorVoteInfo(sortedForegroundColorBallots, GetTotalVoteCountFromAllBallots));
}
internal void OnPixel(Color color, Color previousColor)
{
countExactColors.Increment(color);
var newlyClosedTransitions = new List <ColorContrastTransition>();
foreach (var transition in openTransitions.Values)
{
transition.AddColor(color);
if (transition.IsClosed)
{
newlyClosedTransitions.Add(transition);
if (transition.IsPotentialForegroundBackgroundPair())
{
countExactPairs.Increment(new ColorPair(
transition.StartingColor,
transition.MostContrastingColor
));
}
}
}
foreach (ColorContrastTransition transition in newlyClosedTransitions)
{
openTransitions.Remove(transition.StartingColor);
}
if (previousColor != null && !color.Equals(previousColor))
{
openTransitions[previousColor] = new ColorContrastTransition(previousColor);
}
}
/// <summary>
/// Counts up the BackgroundColor from each entry in _rowResults, then
/// selects the most frequent BackgroundColor as the overall BackgroundColor.
/// </summary>
private ColorVoteInfo GetBackgroundInfo()
{
CountMap <Color> backgroundColorBallots = new CountMap <Color>();
_rowResults.ForEach(r =>
{
Color backgroundColor = r.BackgroundColor;
if (backgroundColor != null)
{
backgroundColorBallots.Increment(r.BackgroundColor);
}
});
var sortedBackgroundColorBallots = backgroundColorBallots.OrderByDescending(x => x.Value);
return(BuildColorVoteInfo(sortedBackgroundColorBallots, GetTotalVoteCountFromAllBallots));
}
// Returns true when entries have lead to a confident conclusion about Text and Background color.
internal ColorContrastResult OnRowEnd()
{
ColorContrastResult result = new ColorContrastResult();
CountMap <ColorPair> pairsWithSimilarTextColor = new CountMap <ColorPair>();
foreach (var exactPairOuter in countExactPairs)
{
foreach (var exactPairInner in countExactPairs)
{
if (exactPairOuter.Key.backgroundColor.Equals(exactPairInner.Key.backgroundColor))
{
if (exactPairOuter.Key.foregroundColor.IsSimilarColor(exactPairInner.Key.foregroundColor))
{
pairsWithSimilarTextColor.Increment(exactPairOuter.Key, exactPairInner.Value);
}
}
}
}
var sortedByValueAndContrast = pairsWithSimilarTextColor.OrderByDescending(x => x.Value)
.ThenByDescending(x => x.Key.ColorContrast());
if (!sortedByValueAndContrast.Any())
{
return(result);
}
var resultPairs = new HashSet <ColorPair>();
var firstEntryCount = sortedByValueAndContrast.First().Value;
if (firstEntryCount < ColorContrastConfig.MinNumberColorTransitions)
{
return(result);
}
var firstEntryCountAdjusted = firstEntryCount / ColorContrastConfig.TransitionCountDominanceFactor;
foreach (var entry in sortedByValueAndContrast)
{
// Only Collect Pairs that have a reasonable occurence count.
if (entry.Value < firstEntryCountAdjusted)
{
break;
}
resultPairs.Add(entry.Key);
}
foreach (var colorPair in resultPairs)
{
result.Add(colorPair);
}
countExactColors.Clear();
openTransitions.Clear();
return(result);
}
internal void OnPixel(Color color)
{
_colorsInRow.Add(color);
_countExactColors.Increment(color);
}