draw2d/samples/linecapjoin/linecapjoin.go

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2015-07-10 00:15:00 +00:00
// Copyright 2010 The draw2d Authors. All rights reserved.
// created: 21/11/2010 by Laurent Le Goff
// Package linecapjoin demonstrates the different line caps and joins.
package linecapjoin
import (
"image/color"
"github.com/llgcode/draw2d"
"github.com/llgcode/draw2d/samples"
)
// Main draws the different line caps and joins.
// This should only be used during testing.
func Main(gc draw2d.GraphicContext, ext string) (string, error) {
// Draw the line
const offset = 75.0
x := 35.0
caps := []draw2d.Cap{draw2d.ButtCap, draw2d.SquareCap, draw2d.RoundCap}
joins := []draw2d.Join{draw2d.BevelJoin, draw2d.MiterJoin, draw2d.RoundJoin}
for i := range caps {
Draw(gc, caps[i], joins[i], x, 50, x, 160, offset)
x += offset
}
// Return the output filename
return samples.Output("linecapjoin", ext), nil
}
// Draw a line with an angle with specified line cap and join
func Draw(gc draw2d.GraphicContext, cap draw2d.Cap, join draw2d.Join,
x0, y0, x1, y1, offset float64) {
gc.Save() // pdf: save & restore needed to isolate caps and joins
gc.SetLineCap(cap)
gc.SetLineJoin(join)
// Draw thick line
gc.SetStrokeColor(color.NRGBA{0x33, 0x33, 0x33, 0xFF})
gc.SetLineWidth(30.0)
gc.MoveTo(x0, y0)
gc.LineTo((x0+x1)/2+offset, (y0+y1)/2)
gc.LineTo(x1, y1)
gc.Stroke()
// Draw thin helping line
gc.SetStrokeColor(color.NRGBA{0xFF, 0x33, 0x33, 0xFF})
gc.SetLineWidth(2.56)
gc.MoveTo(x0, y0)
gc.LineTo((x0+x1)/2+offset, (y0+y1)/2)
gc.LineTo(x1, y1)
gc.Stroke()
gc.Restore()
}