# Create a Drawing

In Luxor you always work with a current drawing, so the first thing to do is to create one.

To create a drawing, and optionally specify the filename, type, and dimensions, use the Drawing constructor function.

To finish a drawing and close the file, use finish, and, if the drawing doesn't appear in your notebook, you can launch an external application to view it using preview.

The @draw, @svg, @png, and @pdf macros are designed to let you quickly create graphics without having to provide the usual boiler-plate functions.

Note

The macros are shortcuts, designed to make it quick and easy to get started. For full control over all parameters, use Drawing.

## Drawings and files

To create a drawing, and optionally specify the filename, type, and dimensions, use the Drawing constructor function.

To finish a drawing and close the file, use finish, and, to launch an external application to view it, use preview.

If you're using Juno or VS Code, then PNG and SVG files should appear in the Plots pane. In a Pluto notebook, output appears above the cell. In a notebook environment, output appears in the next notebook cell.

Note

SVGs are text based, and can get quite big. Up to a certain size, SVGs will be previewable as easily and quickly as PNGs. But very large drawings in SVG format won't necessarily be displayed.

## Quick drawings with macros

The @draw, @svg, @png, and @pdf macros are designed to let you quickly create graphics without having to provide the usual boiler-plate functions. For example, the Julia code:

@svg circle(Point(0, 0), 20, :stroke) 50 50

expands to

Drawing(50, 50, "luxor-drawing-(timestamp).svg")
origin()
background("white")
sethue("black")
circle(Point(0, 0), 20, :stroke)
finish()
preview()

They're just short-cuts - designed to save a bit of typing. You can omit the width and height (thus defaulting to 600 by 600, except for @imagematrix), and you don't have to specify a filename (you'll get time-stamped files in the current working directory). For multiple lines, use either:

@svg begin
setline(10)
sethue("purple")
circle(Point(0, 0), 20, :fill)
end

or (less nicely):

@svg (setline(10);
sethue("purple");
circle(Point(0, 0), 20, :fill)
)

The @draw macro creates a PNG drawing in-memory (not saved in a file). You should see it displayed if you're working in a suitable environment (Juno, VSCode, Jupyter, Pluto).

The SVG equivalent of @draw is @drawsvg.

If you don't specify a size, the defaults are usually 600 by 600. If you don't specify a file name, files created with the macros are placed in your current working directory as luxor-drawing- followed by a time stamp. You don't even have to specify the suffix:

@svg juliacircles(150) 400 400 "test" # saves in "test.svg"

If you want to create drawings with transparent backgrounds, or use variables to specify filenames, you have to use the longer form, rather than the macros:

Drawing()
background(1, 1, 1, 0)
origin()
setline(30)
sethue("green") # assumes current opacity
box(BoundingBox() - 50, :stroke)
finish()
preview()

You can obtain the raw SVG code of a drawing using @savesvg.

## Drawings in memory

You can choose to store the drawing in memory. The advantage is that in-memory drawings are quicker, and can be passed as Julia data. It's useful in some environments to not have to worry about writing files. This syntax for the Drawing function:

Drawing(width, height, surfacetype, [filename])

lets you supply surfacetype as a symbol (:svg or :png). This creates a new drawing of the given surface type and stores the image only in memory if no filename is supplied.

The @draw and @drawsvg macros creates PNG/SVG files in memory.

You can specify :image as the surface type. This allows you to copy the current drawing into a 2D matrix (using image_as_matrix). See the Images chapter for more information.

Use svgstring to obtain the SVG source for a finished SVG drawing.

## Interactive drawings

### Using Pluto

Pluto notebooks typically display the final result of a piece of code in a cell. So there are various ways you can organize your drawing code. For example:

using Luxor, PlutoUI, Colors

@bind x Slider(0:0.1:12)

@bind y Slider(1:12)

@draw begin
setopacity(0.8)
for i in 0:0.1:1
sethue(HSB(360i, .8, .8))
squircle(O, 50, 50, :fill, rt = x * i)
rotate(2π/y)
end
end 100 100

or

begin
d = Drawing(800, 800, :svg)
origin()
for (n, m) in enumerate(exp10.(range(0.0, 2, step=0.2)))
setmesh(mesh(convert(Vector{Point}, BoundingBox()/m),
["darkviolet","gold2", "firebrick2", "slateblue4"]))
rotate(π/7)
paint()
end
finish()
d
end

### Using Jupyter notebooks (IJulia and Interact)

Currently, you should use an in-memory SVG drawing to display graphics if you're using Interact.jl. This example provides an HSB color widget.

using Interact, Colors, Luxor
@manipulate for h in 0:360, s in 0:0.01:1, b in 0:0.01:1
d = Drawing(300, 300, :svg)
sethue(Colors.HSB(h, s, b))
origin()
circle(Point(0, 0), 100, :fill)
end