juliendorra/canvas-hpgl

canvas-hpgl

CanvasHpgl gives a HTML Canvas compatible API for producing HPGL. It uses canvas-polyline which produces all output using only straight lines, and then output them using the HPGL PU and PD commands.

Usage

var ctx = new CanvasHpgl() // Takes a single Canvas API contexts or an array of them
ctx.rect(0, 0, 100, 100)
// PU 0,0
// PD 100,0
// PD 100,100
// PD 0,100
// PD 0,0

penColors

You can set which pen to use for a given color like this.

var penColors = {
    '#C00': 3,
    '#0C0': 2,
}
var ctx = new CanvasHpgl(penColors) // Takes a single Canvas API contexts or an array of them
ctx.strokeStyle('#C00') // SP 3;
ctx.rect(0, 0, 100, 100)
ctx.strokeStyle('#0C0') // SP 2;
ctx.rect(200, 0, 100, 100)

Backstory

My initial motivation for creating this project was so I could use the HTML Canvas API with Roland DPX-3300 plotter. The plotter only understands HPGL. I started by creating d3-hpgl, which translates Canvas commands in to the equivilient HPGL, however HPGL (at least version for my plotter) doesn't have native support for quadtractics, beziers or elipses. Additionally I wanted to have support for transformations, so I created this library.

Thanks

The code has been adapted from d3-path, and uses adaptive-bezier-curve, adaptive-quadratic-curve and transformation-matrix.