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PdfTextExtractor: Apply simple heuristics to join different text blocks checking matrix "collinearity".

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Valeriano A.R.
2017-04-12 22:49:00 +02:00
parent 0938553510
commit a5879ec9c2
1 changed files with 62 additions and 19 deletions
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81
VAR.PdfTools/PdfTextExtractor.cs
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@@ -1,4 +1,5 @@
using System.Collections.Generic;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
@@ -56,6 +57,11 @@ namespace VAR.PdfTools
Idenity();
}
public Matrix3x3(double a, double b, double c, double d, double e, double f)
{
Set(a, b, c, d, e, f);
}
#endregion
#region Public methods
@@ -73,6 +79,19 @@ namespace VAR.PdfTools
_matrix[2, 2] = 1.0;
}
public void Set(double a, double b, double c, double d, double e, double f)
{
_matrix[0, 0] = a;
_matrix[1, 0] = b;
_matrix[2, 0] = 0;
_matrix[0, 1] = c;
_matrix[1, 1] = d;
_matrix[2, 1] = 0;
_matrix[0, 2] = e;
_matrix[1, 2] = f;
_matrix[2, 2] = 1;
}
public Vector3D Multiply(Vector3D vect)
{
Vector3D vectResult = new Vector3D();
@@ -118,6 +137,19 @@ namespace VAR.PdfTools
return newMatrix;
}
public bool IsCollinear(Matrix3x3 otherMatrix, double horizontalDelta = 0.00001, double verticalDelta = 0.00001)
{
double epsilon = 0.00001;
return (
Math.Abs(_matrix[0, 0] - otherMatrix.Matrix[0, 0]) <= epsilon &&
Math.Abs(_matrix[1, 0] - otherMatrix.Matrix[1, 0]) <= epsilon &&
Math.Abs(_matrix[0, 1] - otherMatrix.Matrix[0, 1]) <= epsilon &&
Math.Abs(_matrix[1, 1] - otherMatrix.Matrix[1, 1]) <= epsilon &&
Math.Abs(_matrix[0, 2] - otherMatrix.Matrix[0, 2]) <= horizontalDelta &&
Math.Abs(_matrix[1, 2] - otherMatrix.Matrix[1, 2]) <= verticalDelta &&
true);
}
#endregion
}
@@ -367,15 +399,7 @@ namespace VAR.PdfTools
private void OpSetGraphMatrix(double a, double b, double c, double d, double e, double f)
{
_graphicsMatrix.Matrix[0, 0] = a;
_graphicsMatrix.Matrix[1, 0] = b;
_graphicsMatrix.Matrix[2, 0] = 0;
_graphicsMatrix.Matrix[0, 1] = c;
_graphicsMatrix.Matrix[1, 1] = d;
_graphicsMatrix.Matrix[2, 1] = 0;
_graphicsMatrix.Matrix[0, 2] = e;
_graphicsMatrix.Matrix[1, 2] = f;
_graphicsMatrix.Matrix[2, 2] = 1;
_graphicsMatrix.Set(a, b, c, d, e, f);
}
private void OpBeginText()
@@ -418,16 +442,35 @@ namespace VAR.PdfTools
private void OpSetTextMatrix(double a, double b, double c, double d, double e, double f)
{
double halfSpaceWidth = 0;
double horizontalDelta = 0;
Matrix3x3 newMatrix = new Matrix3x3(a, b, c, d, e, f);
if (_font != null)
{
halfSpaceWidth = _font.GetCharWidth(' ') * _fontSize;
}
horizontalDelta = (_textWidth + halfSpaceWidth);
if (_textMatrix.IsCollinear(newMatrix, horizontalDelta: horizontalDelta))
{
return;
}
if (_currentTextElement != null)
{
if (_currentTextElement.Font != null)
{
halfSpaceWidth = _currentTextElement.Font.GetCharWidth(' ') * _currentTextElement.FontSize;
}
horizontalDelta = (_currentTextElement.VisibleWidth + halfSpaceWidth);
if (_currentTextElement.Matrix.IsCollinear(newMatrix, horizontalDelta: horizontalDelta))
{
FlushTextElementSoft();
_textMatrix = newMatrix;
return;
}
}
FlushTextElement();
_textMatrix.Matrix[0, 0] = a;
_textMatrix.Matrix[1, 0] = b;
_textMatrix.Matrix[2, 0] = 0;
_textMatrix.Matrix[0, 1] = c;
_textMatrix.Matrix[1, 1] = d;
_textMatrix.Matrix[2, 1] = 0;
_textMatrix.Matrix[0, 2] = e;
_textMatrix.Matrix[1, 2] = f;
_textMatrix.Matrix[2, 2] = 1;
_textMatrix = newMatrix;
}
private void OpTextPut(string text)