private HashSet <LineShape> FilterHorizontalLines(Image hlines, BoundedObjectGrid <CheckboxShape> checkboxGrid)
{
HashSet <LineShape> lines = new HashSet <LineShape>();
int minThickLineWidth = LineDetector.MinThickLineWidth.MulDiv(hlines.VerticalResolution, 200);
int minThickLineLength = LineDetector.MinThickLineLength.MulDiv(hlines.HorizontalResolution, 200);
int maxBoxSize = this.MaxBoxSize.MulDiv(hlines.HorizontalResolution, 200);
// find connected components and do preliminary filtering
foreach (ConnectedComponent component in hlines.FindConnectedComponents(8))
{
Rectangle bounds = component.Bounds;
int maxWidth = component.MaxHeight();
bool isBad = false;
if (bounds.Width.Between(minThickLineWidth, minThickLineLength - 1) &&
bounds.Height.Between(minThickLineWidth, minThickLineLength - 1) &&
maxWidth > minThickLineLength)
{
// too thick for the length
isBad = true;
}
if (!isBad && bounds.Width <= maxBoxSize && checkboxGrid != null && checkboxGrid.EnumObjects(bounds).Any())
{
// is part of the check box
isBad = true;
}
if (isBad)
{
hlines.SetWhite(bounds);
}
else
{
LineShape newline = new LineShape(bounds, maxWidth, LineTypes.Horizontal);
lines.Add(newline);
}
}
// find line vectors
AlignedObjectGrid <LineShape> grid = new AlignedObjectGrid <LineShape>(hlines.Bounds, 10, 20, RectangleLTRBComparer.Default);
grid.AddRange(lines, true, true);
int minLineLength = (this.MinHorizontalLineLength * hlines.HorizontalResolution).Round();
int maxGap = LineDetector.MaxLineGap.MulDiv(hlines.HorizontalResolution, 200);
int tolerance = 3.MulDiv(hlines.VerticalResolution, 200);
HashSet <LineShape> newlines = new HashSet <LineShape>();
foreach (LineShape line in lines)
{
if (line.VerticalAlignment == VerticalAlignment.None)
{
IList <LineShape> alignedLines = grid.FindVerticalAlignment(
line,
VerticalAlignment.Center,
maxGap,
tolerance,
(result, bounds) => bounds.Width >= minLineLength && (result.Count >= 2 || result.Any(o => o.Bounds.Width >= minLineLength)));
if (alignedLines.Count > 0)
{
LineShape newline = new LineShape(
Rectangle.Union(alignedLines.Select(x => x.Bounds)),
alignedLines[0].Begin,
alignedLines[alignedLines.Count - 1].End,
alignedLines.Max(x => x.Width),
LineTypes.Horizontal);
newlines.Add(newline);
}
}
}
// remove merged and short lines
lines.RemoveWhere(x =>
{
// remove merged lines
bool remove = x.VerticalAlignment != VerticalAlignment.None;
// remove small not merged lines
// also delete them from the image
if (x.VerticalAlignment == VerticalAlignment.None && x.Bounds.Width < minLineLength)
{
hlines.SetWhite(x.Bounds);
remove = true;
}
return(remove);
});
lines.UnionWith(newlines);
return(lines);
}
private HashSet <LineShape> FilterVerticalLines(Image vlines, Image hlines, BoundedObjectGrid <CheckboxShape> checkboxGrid)
{
HashSet <LineShape> lines = new HashSet <LineShape>();
int minThickLineWidth = LineDetector.MinThickLineWidth.MulDiv(vlines.HorizontalResolution, 200);
int minThickLineLength = LineDetector.MinThickLineLength.MulDiv(vlines.VerticalResolution, 200);
int maxBoxSize = this.MaxBoxSize.MulDiv(vlines.VerticalResolution, 200);
// find connected components and do preliminary filtering
foreach (ConnectedComponent component in vlines.FindConnectedComponents(8))
{
Rectangle bounds = component.Bounds;
int maxWidth = component.MaxWidth();
bool isBad = false;
if (bounds.Width.Between(minThickLineWidth, minThickLineLength - 1) &&
bounds.Height.Between(minThickLineWidth, minThickLineLength - 1) &&
maxWidth > minThickLineLength)
{
// too thick for the length
isBad = true;
}
if (!isBad && bounds.Height <= maxBoxSize && checkboxGrid != null && checkboxGrid.EnumObjects(bounds).Any())
{
// is part of the check box
isBad = true;
}
if (isBad)
{
vlines.SetWhite(bounds);
}
else
{
Point begin = new Point(component.GetLine(bounds.Y).Center, bounds.Y);
Point end = new Point(component.GetLine(bounds.Bottom - 1).Center, bounds.Bottom - 1);
LineShape line = new LineShape(bounds, begin, end, maxWidth, LineTypes.Vertical);
lines.Add(line);
}
}
// find line vectors
AlignedObjectGrid <LineShape> grid = new AlignedObjectGrid <LineShape>(vlines.Bounds, 10, 20, RectangleTBLRComparer.Default);
grid.AddRange(lines, true, true);
int minLineLength = (this.MinVerticalLineLength * vlines.VerticalResolution).Round();
int maxGap = LineDetector.MaxLineGap.MulDiv(vlines.VerticalResolution, 200);
int tolerance = 6.MulDiv(vlines.HorizontalResolution, 200);
HashSet <LineShape> newlines = new HashSet <LineShape>();
foreach (LineShape line in lines)
{
if (line.HorizontalAlignment == HorizontalAlignment.None)
{
IList <LineShape> alignedLines = grid.FindHorizontalAlignment(
line,
HorizontalAlignment.Center,
Math.Min(maxGap, line.Bounds.Height),
tolerance,
(result, bounds) => (bounds.Height >= minLineLength && (result.Count >= 3 || result.Any(o => o.Bounds.Height >= minLineLength))) || LineHasIntersectionsOnBothEnds(bounds));
if (alignedLines.Count > 0)
{
LineShape newline = new LineShape(
Rectangle.Union(alignedLines.Select(x => x.Bounds)),
alignedLines[0].Begin,
alignedLines[alignedLines.Count - 1].End,
alignedLines.Max(x => x.Width),
LineTypes.Vertical);
newlines.Add(newline);
}
}
}
// remove merged and short lines
lines.RemoveWhere(x =>
{
// remove merged lines
bool remove = x.HorizontalAlignment != HorizontalAlignment.None;
// remove small not merged lines
// also delete them from the image
if (x.HorizontalAlignment == HorizontalAlignment.None && x.Bounds.Height < minLineLength && !LineHasIntersectionsOnBothEnds(x.Bounds))
{
vlines.SetWhite(x.Bounds);
remove = true;
}
return(remove);
});
lines.UnionWith(newlines);
bool LineHasIntersectionsOnBothEnds(Rectangle bounds)
{
if (hlines != null)
{
int boxheight = Math.Min(bounds.Width, bounds.Height);
Rectangle top = new Rectangle(bounds.X, bounds.Y, bounds.Width, boxheight);
top.Inflate(0, 2 * boxheight);
top.Intersect(hlines.Bounds);
Rectangle bottom = new Rectangle(bounds.X, bounds.Bottom - boxheight, bounds.Width, boxheight);
bottom.Inflate(0, 2 * boxheight);
bottom.Intersect(hlines.Bounds);
return(!hlines.IsAllWhite(top) && !hlines.IsAllWhite(bottom));
}
else
{
return(false);
}
}
return(lines);
}