struct Cairo::PathData

• Cairo::PathData
• Struct
• Value
• Object

Overview

Wrapper for LibCairo::PathDataT

PathData is used to represent the path data inside a Path.

The data structure is designed to try to balance the demands of efficiency and ease-of-use. A path is represented as an array of PathData, which is a union of headers and points.

Each portion of the path is represented by one or more elements in the array, (one header followed by 0 or more points). The length value of the header is the number of array elements for the current portion including the header, (ie. length == 1 + # of points), and where the number of points for each element type is as follows:

• PathDataType::MoveTo: 1 point
• PathDataType::LineTo: 1 point
• PathDataType::CurveTo: 3 points
• PathDataType::ClosePath: 0 points

The semantics and ordering of the coordinate values are consistent with Context#move_to, Context#line_to, Context#curve_to, and Context#close_path.

Here is sample code for iterating through a Path:

i = 0
path = ctx.copy_path
while i < path.num_data
  data = path[i]
  case data.header.type
  when PathDataType::MoveTo
      data1 = path[i + 1]
      printf("MoveTo(%5.2f, %5.2f)\n", data1.point.x, data1.point.y)
  when PathDataType::LineTo
      data1 = path[i + 1]
      printf("LineTo(%5.2f, %5.2f)\n", data1.point.x, data1.point.y)
  when PathDataType::CurveTo
      data1 = path[i + 1]
      data2 = path[i + 2]
      data3 = path[i + 3]
      printf("CurveTo(%5.2f, %5.2f)\n", data1.point.x, data1.point.y)
      printf("       (%5.2f, %5.2f)\n", data2.point.x, data2.point.y)
      printf("       (%5.2f, %5.2f)\n", data3.point.x, data3.point.y)
  when PathDataType::ClosePath
      puts "ClosePath"
  end
  i += data.header.length
end

Defined in:

cairo/path_data.cr

Constructors

• .new(point : Point)
• .new(data : LibCairo::PathDataT)
• .new(header : PathDataHeader)

Instance Method Summary

• #header : PathDataHeader
• #header=(header : PathDataHeader)
• #point : Point
• #point=(point : Point)
• #to_cairo_path_data : LibCairo::PathDataT
• #to_unsafe : LibCairo::PPathDataT

Constructor Detail

Instance Method Detail