Method DrawColoredPolygon

IO/ExportPDF/vtkPDFContextDevice2D.cxx:1041–1097

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//------------------------------------------------------------------------------
void vtkPDFContextDevice2D::DrawColoredPolygon(
  float* points, int numPoints, unsigned char* colors, int nc_comps)
{
  assert(numPoints > 0);
  assert(points != nullptr);

  // Just use the standard draw method if there is a texture or colors are not
  // specified:
  if (this->Brush->GetTexture() != nullptr || nc_comps == 0)
  {
    this->DrawPolygon(points, numPoints);
    return;
  }

  // If all of the points have the same color, use a more compact method to
  // draw the poly:
  bool sameColor = true;
  for (int i = 1; i < numPoints && sameColor; ++i)
  {
    sameColor = std::equal(colors, colors + nc_comps, colors + (i * nc_comps));
  }
  if (sameColor)
  {
    const vtkColor4ub oldBrush = this->Brush->GetColorObject();
    switch (nc_comps)
    {
      case 4:
        this->Brush->SetOpacity(colors[3]);
        [[fallthrough]];
      case 3:
        this->Brush->SetColor(colors);
        break;

      default:
        vtkWarningMacro("Unsupported number of color components: " << nc_comps);
        return;
    }

    this->DrawPolygon(points, numPoints);
    this->Brush->SetColor(oldBrush);
    return;
  }

  this->PushGraphicsState();

  HPDF_REAL bbox[4];
  GetPointBounds(points, numPoints, bbox);

  HPDF_Shading shading = HPDF_Shading_New(this->Impl->Document,
    HPDF_SHADING_FREE_FORM_TRIANGLE_MESH, HPDF_CS_DEVICE_RGB, bbox[0], bbox[1], bbox[2], bbox[3]);

  PolygonToShading(points, numPoints, colors, nc_comps, shading);

  HPDF_Page_SetShading(this->Impl->Page, shading);

  this->PopGraphicsState();
}