Color and lineweight

A new entity takes its color and lineweight from its layer, 0 unless it names another: Layers sets them there.

C++Copy
DxfIO::Document drawing = DxfIO::Create(DxfIO::Version::R2018);

DxfIO::Entities::Line plain{};
plain.End = {.X = 100, .Y = 0, .Z = 0};
std::println("layer {}, color {}, lineweight {}", plain.Record.Layer, plain.Record.Color, plain.Record.Lineweight);
DxfIO::Edit::Add(drawing, plain);

textCopy
layer 0, color 256, lineweight -1

Color is an AutoCAD Color Index from 1 to 255, or Colors::Bylayer (256) to take the layer’s color, or Colors::Byblock (0) to take the color of the block insert the entity is drawn in. Colors::White, 7, is drawn white on a dark background and black on a light one.

C++Copy
DxfIO::Entities::Line indexed{};
indexed.Start = {.X = 0, .Y = 10, .Z = 0};
indexed.End = {.X = 100, .Y = 10, .Z = 0};
indexed.Record.Color = 1;
DxfIO::Edit::Add(drawing, indexed);

Rgb adds a true color as 0xRRGGBB, written from R2004 on. A release before R2004 keeps only Color, so give it an index near the true color as well.

C++Copy
DxfIO::Entities::Line orange{};
orange.Start = {.X = 0, .Y = 20, .Z = 0};
orange.End = {.X = 100, .Y = 20, .Z = 0};
orange.Record.Color = 30;
orange.Record.Rgb = 0xFF8000;
DxfIO::Edit::Add(drawing, orange);

Lineweight is in hundredths of a millimeter, so 50 is 0.50 mm, and is written from R2000 on. Lineweights::Bylayer (-1) takes the layer’s, Lineweights::Byblock (-2) the block insert’s, and Lineweights::Standard (-3) the drawing’s default, which $LWDEFAULT gives.

C++Copy
DxfIO::Entities::Line heavy{};
heavy.Start = {.X = 0, .Y = 30, .Z = 0};
heavy.End = {.X = 100, .Y = 30, .Z = 0};
heavy.Record.Lineweight = 50;
DxfIO::Edit::Add(drawing, heavy);

Hidden makes the entity invisible; it stays in the drawing. Transparency, from R2004, is empty while the entity takes its layer’s.

C++Copy
DxfIO::Entities::Line invisible{};
invisible.Start = {.X = 0, .Y = 40, .Z = 0};
invisible.End = {.X = 100, .Y = 40, .Z = 0};
invisible.Record.Hidden = true;
DxfIO::Edit::Add(drawing, invisible);

C++Copy
const auto saved = DxfIO::SaveFile(drawing, "colors.dxf");
if (!saved)
{
  std::println("{}", saved.error().What);
  return 1;
}