Function findScanRange

Rendering/FreeType/vtkFreeTypeTools.cxx:1628–1673

Given the corners of a rectangle (TL, TR, BL, BR), the vectors that separate them (dx = TR - TL = BR - BL, dy = TR - BR = TL - BL), and the y value to scan, return the minimum and maximum x values that the rectangle contains.

// y value to scan, return the minimum and maximum x values that the rectangle
// contains.
bool findScanRange(const vtkVector2i& TL, const vtkVector2i& TR, const vtkVector2i& BL,
  const vtkVector2i& BR, const vtkVector2i& dx, const vtkVector2i& dy, int y, int& min, int& max)
{
  // Initialize the min and max to a known invalid range using the bounds of the
  // rectangle:
  min = std::max({ TL[0], TR[0], BL[0], BR[0] });
  max = std::min({ TL[0], TR[0], BL[0], BR[0] });

  float lineParam;
  int numIntersections = 0;

  // Top
  if (getIntersectionParameter(TL, dx, y, lineParam))
  {
    int x = evaluateLineXOnly(TL, dx, lineParam);
    min = std::min(min, x);
    max = std::max(max, x);
    ++numIntersections;
  }
  // Bottom
  if (getIntersectionParameter(BL, dx, y, lineParam))
  {
    int x = evaluateLineXOnly(BL, dx, lineParam);
    min = std::min(min, x);
    max = std::max(max, x);
    ++numIntersections;
  }
  // Left
  if (getIntersectionParameter(BL, dy, y, lineParam))
  {
    int x = evaluateLineXOnly(BL, dy, lineParam);
    min = std::min(min, x);
    max = std::max(max, x);
    ++numIntersections;
  }
  // Right
  if (getIntersectionParameter(BR, dy, y, lineParam))
  {
    int x = evaluateLineXOnly(BR, dy, lineParam);
    min = std::min(min, x);
    max = std::max(max, x);
    ++numIntersections;
  }

  return numIntersections != 0;
}

// Clamp value to stay between the minimum and maximum extent for the
// specified dimension.