forked from unidoc/unidoc
/
bezier_curve.go
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/
bezier_curve.go
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/*
* This file is subject to the terms and conditions defined in
* file 'LICENSE.md', which is part of this source code package.
*/
package draw
import (
"math"
"github.com/unidoc/unidoc/pdf/model"
)
// Cubic bezier curves are defined by:
// R(t) = P0*(1-t)^3 + P1*3*t*(1-t)^2 + P2*3*t^2*(1-t) + P3*t^3
// where P0 is the current point, P1, P2 control points and P3 the final point.
type CubicBezierCurve struct {
P0 Point // Starting point.
P1 Point // Control point 1.
P2 Point // Control point 2.
P3 Point // Final point.
}
func NewCubicBezierCurve(x0, y0, x1, y1, x2, y2, x3, y3 float64) CubicBezierCurve {
curve := CubicBezierCurve{}
curve.P0 = NewPoint(x0, y0)
curve.P1 = NewPoint(x1, y1)
curve.P2 = NewPoint(x2, y2)
curve.P3 = NewPoint(x3, y3)
return curve
}
// Add X,Y offset to all points on a curve.
func (curve CubicBezierCurve) AddOffsetXY(offX, offY float64) CubicBezierCurve {
curve.P0.X += offX
curve.P1.X += offX
curve.P2.X += offX
curve.P3.X += offX
curve.P0.Y += offY
curve.P1.Y += offY
curve.P2.Y += offY
curve.P3.Y += offY
return curve
}
func (curve CubicBezierCurve) GetBounds() model.PdfRectangle {
minX := curve.P0.X
maxX := curve.P0.X
minY := curve.P0.Y
maxY := curve.P0.Y
// 1000 points.
for t := 0.0; t <= 1.0; t += 0.001 {
Rx := curve.P0.X*math.Pow(1-t, 3) +
curve.P1.X*3*t*math.Pow(1-t, 2) +
curve.P2.X*3*math.Pow(t, 2)*(1-t) +
curve.P3.X*math.Pow(t, 3)
Ry := curve.P0.Y*math.Pow(1-t, 3) +
curve.P1.Y*3*t*math.Pow(1-t, 2) +
curve.P2.Y*3*math.Pow(t, 2)*(1-t) +
curve.P3.Y*math.Pow(t, 3)
if Rx < minX {
minX = Rx
}
if Rx > maxX {
maxX = Rx
}
if Ry < minY {
minY = Ry
}
if Ry > maxY {
maxY = Ry
}
}
bounds := model.PdfRectangle{}
bounds.Llx = minX
bounds.Lly = minY
bounds.Urx = maxX
bounds.Ury = maxY
return bounds
}
type CubicBezierPath struct {
Curves []CubicBezierCurve
}
func NewCubicBezierPath() CubicBezierPath {
bpath := CubicBezierPath{}
bpath.Curves = []CubicBezierCurve{}
return bpath
}
func (this CubicBezierPath) AppendCurve(curve CubicBezierCurve) CubicBezierPath {
this.Curves = append(this.Curves, curve)
return this
}
func (bpath CubicBezierPath) Copy() CubicBezierPath {
bpathcopy := CubicBezierPath{}
bpathcopy.Curves = []CubicBezierCurve{}
for _, c := range bpath.Curves {
bpathcopy.Curves = append(bpathcopy.Curves, c)
}
return bpathcopy
}
func (bpath CubicBezierPath) Offset(offX, offY float64) CubicBezierPath {
for i, c := range bpath.Curves {
bpath.Curves[i] = c.AddOffsetXY(offX, offY)
}
return bpath
}
func (bpath CubicBezierPath) GetBoundingBox() Rectangle {
bbox := Rectangle{}
minX := 0.0
maxX := 0.0
minY := 0.0
maxY := 0.0
for idx, c := range bpath.Curves {
curveBounds := c.GetBounds()
if idx == 0 {
minX = curveBounds.Llx
maxX = curveBounds.Urx
minY = curveBounds.Lly
maxY = curveBounds.Ury
continue
}
if curveBounds.Llx < minX {
minX = curveBounds.Llx
}
if curveBounds.Urx > maxX {
maxX = curveBounds.Urx
}
if curveBounds.Lly < minY {
minY = curveBounds.Lly
}
if curveBounds.Ury > maxY {
maxY = curveBounds.Ury
}
}
bbox.X = minX
bbox.Y = minY
bbox.Width = maxX - minX
bbox.Height = maxY - minY
return bbox
}