// ArcNegative draws an arc with a negative angle (anti clockwise).
func ArcNegative(gc draw2d.GraphicContext, xc, yc, width, height float64) {
xc += width / 2
yc += height / 2
radiusX, radiusY := width/2, height/2
startAngle := 45.0 * (math.Pi / 180.0) /* angles are specified */
angle := -225 * (math.Pi / 180.0) /* clockwise in radians */
gc.SetLineWidth(width / 10)
gc.SetLineCap(draw2d.ButtCap)
gc.SetStrokeColor(image.Black)
gc.ArcTo(xc, yc, radiusX, radiusY, startAngle, angle)
gc.Stroke()
// fill a circle
gc.SetStrokeColor(color.NRGBA{255, 0x33, 0x33, 0x80})
gc.SetFillColor(color.NRGBA{255, 0x33, 0x33, 0x80})
gc.SetLineWidth(width / 20)
gc.MoveTo(xc+math.Cos(startAngle)*radiusX, yc+math.Sin(startAngle)*radiusY)
gc.LineTo(xc, yc)
gc.LineTo(xc-radiusX, yc)
gc.Stroke()
gc.ArcTo(xc, yc, width/10.0, height/10.0, 0, 2*math.Pi)
gc.Fill()
}
// PathTransform scales a path differently in horizontal and vertical direction.
func PathTransform(gc draw2d.GraphicContext, x, y, width, height float64) {
gc.Save()
gc.SetLineWidth(width / 10)
gc.Translate(x+width/2, y+height/2)
gc.Scale(1, 4)
gc.ArcTo(0, 0, width/8, height/8, 0, math.Pi*2)
gc.Close()
gc.Stroke()
gc.Restore()
}
// Draw the droid on a certain position.
func Draw(gc draw2d.GraphicContext, x, y float64) {
// set the fill and stroke color of the droid
gc.SetFillColor(color.RGBA{0x44, 0xff, 0x44, 0xff})
gc.SetStrokeColor(color.RGBA{0x44, 0x44, 0x44, 0xff})
// set line properties
gc.SetLineCap(draw2d.RoundCap)
gc.SetLineWidth(5)
// head
gc.MoveTo(x+30, y+70)
gc.ArcTo(x+80, y+70, 50, 50, 180*(math.Pi/180), 180*(math.Pi/180))
gc.Close()
gc.FillStroke()
gc.MoveTo(x+60, y+25)
gc.LineTo(x+50, y+10)
gc.MoveTo(x+100, y+25)
gc.LineTo(x+110, y+10)
gc.Stroke()
// left eye
draw2dkit.Circle(gc, x+60, y+45, 5)
gc.FillStroke()
// right eye
draw2dkit.Circle(gc, x+100, y+45, 5)
gc.FillStroke()
// body
draw2dkit.RoundedRectangle(gc, x+30, y+75, x+30+100, y+75+90, 10, 10)
gc.FillStroke()
draw2dkit.Rectangle(gc, x+30, y+75, x+30+100, y+75+80)
gc.FillStroke()
// left arm
draw2dkit.RoundedRectangle(gc, x+5, y+80, x+5+20, y+80+70, 10, 10)
gc.FillStroke()
// right arm
draw2dkit.RoundedRectangle(gc, x+135, y+80, x+135+20, y+80+70, 10, 10)
gc.FillStroke()
// left leg
draw2dkit.RoundedRectangle(gc, x+50, y+150, x+50+20, y+150+50, 10, 10)
gc.FillStroke()
// right leg
draw2dkit.RoundedRectangle(gc, x+90, y+150, x+90+20, y+150+50, 10, 10)
gc.FillStroke()
}
// Arc draws a link between two points
func Arc(gc draw2d.GraphicContext, x, y1, y2 float64) {
// Center
yc := (y1 + y2) / 2
// x radius
xRadius := y2 - y1
// y radius
yRadius := y2 - yc
// Start at -45 degrees
startAngle := -math.Pi / 2
// 180 degrees = half a circle
angle := math.Pi
gc.ArcTo(x, yc, xRadius, yRadius, startAngle, angle)
gc.Stroke()
gc.Fill()
}