impeller::VertexWriter Class Reference

An interface for generating a multi contour polyline as a triangle strip. More...

#include <path_component.h>

Public Member Functions
	VertexWriter (std::vector< Point > &points, std::vector< uint16_t > &indices)
	~VertexWriter ()=default
void	EndContour ()
void	Write (Point point)

Detailed Description

An interface for generating a multi contour polyline as a triangle strip.

Definition at line 21 of file path_component.h.

Constructor & Destructor Documentation

VertexWriter()

impeller::VertexWriter::VertexWriter ( std::vector< Point > &  points, std::vector< uint16_t > &  indices  )

explicit

Definition at line 13 of file path_component.cc.

    : points_(points), indices_(indices) {}

~VertexWriter()

impeller::VertexWriter::~VertexWriter ( )

default

Member Function Documentation

EndContour()

void impeller::VertexWriter::EndContour

(

)

Definition at line 17 of file path_component.cc.

                              {
  if (points_.size() == 0u || contour_start_ == points_.size() - 1) {
    // Empty or first contour.
    return;
  }
 
  auto start = contour_start_;
  auto end = points_.size() - 1;
  // All filled paths are drawn as if they are closed, but if
  // there is an explicit close then a lineTo to the origin
  // is inserted. This point isn't strictly necesary to
  // correctly render the shape and can be dropped.
  if (points_[end] == points_[start]) {
    end--;
  }
 
  // Triangle strip break for subsequent contours
  if (contour_start_ != 0) {
    auto back = indices_.back();
    indices_.push_back(back);
    indices_.push_back(start);
    indices_.push_back(start);
 
    // If the contour has an odd number of points, insert an extra point when
    // bridging to the next contour to preserve the correct triangle winding
    // order.
    if (previous_contour_odd_points_) {
      indices_.push_back(start);
    }
  } else {
    indices_.push_back(start);
  }
 
  size_t a = start + 1;
  size_t b = end;
  while (a < b) {
    indices_.push_back(a);
    indices_.push_back(b);
    a++;
    b--;
  }
  if (a == b) {
    indices_.push_back(a);
    previous_contour_odd_points_ = false;
  } else {
    previous_contour_odd_points_ = true;
  }
  contour_start_ = points_.size();
}

Write()

void impeller::VertexWriter::Write

(

Point

point

)

Definition at line 67 of file path_component.cc.

                                    {
  points_.push_back(point);
}

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The documentation for this class was generated from the following files:

• impeller/geometry/path_component.h
• impeller/geometry/path_component.cc