some improvments

internal/pdf/contentstream/draw/bezier_curve.go

@@ -89,9 +89,9 @@ func NewCubicBezierPath() CubicBezierPath {
 	return bpath
 }
 
-func (this CubicBezierPath) AppendCurve(curve CubicBezierCurve) CubicBezierPath {
-	this.Curves = append(this.Curves, curve)
-	return this
+func (c CubicBezierPath) AppendCurve(curve CubicBezierCurve) CubicBezierPath {
+	c.Curves = append(c.Curves, curve)
+	return c
 }
 
 func (bpath CubicBezierPath) Copy() CubicBezierPath {

internal/pdf/contentstream/draw/path.go

@@ -11,36 +11,36 @@ func NewPath() Path {
 	return path
 }
 
-func (this Path) AppendPoint(point Point) Path {
-	this.Points = append(this.Points, point)
-	return this
+func (p Path) AppendPoint(point Point) Path {
+	p.Points = append(p.Points, point)
+	return p
 }
 
-func (this Path) RemovePoint(number int) Path {
-	if number < 1 || number > len(this.Points) {
-		return this
+func (p Path) RemovePoint(number int) Path {
+	if number < 1 || number > len(p.Points) {
+		return p
 	}
 
 	idx := number - 1
-	this.Points = append(this.Points[:idx], this.Points[idx+1:]...)
-	return this
+	p.Points = append(p.Points[:idx], p.Points[idx+1:]...)
+	return p
 }
 
-func (this Path) Length() int {
-	return len(this.Points)
+func (p Path) Length() int {
+	return len(p.Points)
 }
 
-func (this Path) GetPointNumber(number int) Point {
-	if number < 1 || number > len(this.Points) {
+func (p Path) GetPointNumber(number int) Point {
+	if number < 1 || number > len(p.Points) {
 		return Point{}
 	}
-	return this.Points[number-1]
+	return p.Points[number-1]
 }
 
-func (path Path) Copy() Path {
+func (p Path) Copy() Path {
 	pathcopy := Path{}
 	pathcopy.Points = []Point{}
-	for _, p := range path.Points {
+	for _, p := range p.Points {
 		pathcopy.Points = append(pathcopy.Points, p)
 	}
 	return pathcopy

internal/pdf/contentstream/draw/point.go

@@ -21,10 +21,10 @@ func (p Point) Add(dx, dy float64) Point {
 }
 
 // Add vector to a point.
-func (this Point) AddVector(v Vector) Point {
-	this.X += v.Dx
-	this.Y += v.Dy
-	return this
+func (p Point) AddVector(v Vector) Point {
+	p.X += v.Dx
+	p.Y += v.Dy
+	return p
 }
 
 func (p Point) String() string {

internal/pdf/contentstream/draw/vector.go

@@ -43,13 +43,13 @@ func (v Vector) Rotate(phi float64) Vector {
 }
 
 // Change the sign of the vector: -vector.
-func (this Vector) Flip() Vector {
-	mag := this.Magnitude()
-	theta := this.GetPolarAngle()
+func (v Vector) Flip() Vector {
+	mag := v.Magnitude()
+	theta := v.GetPolarAngle()
 
-	this.Dx = mag * math.Cos(theta+math.Pi)
-	this.Dy = mag * math.Sin(theta+math.Pi)
-	return this
+	v.Dx = mag * math.Cos(theta+math.Pi)
+	v.Dy = mag * math.Sin(theta+math.Pi)
+	return v
 }
 
 func (v Vector) FlipY() Vector {
@@ -62,19 +62,19 @@ func (v Vector) FlipX() Vector {
 	return v
 }
 
-func (this Vector) Scale(factor float64) Vector {
-	mag := this.Magnitude()
-	theta := this.GetPolarAngle()
+func (v Vector) Scale(factor float64) Vector {
+	mag := v.Magnitude()
+	theta := v.GetPolarAngle()
 
-	this.Dx = factor * mag * math.Cos(theta)
-	this.Dy = factor * mag * math.Sin(theta)
-	return this
+	v.Dx = factor * mag * math.Cos(theta)
+	v.Dy = factor * mag * math.Sin(theta)
+	return v
 }
 
-func (this Vector) Magnitude() float64 {
-	return math.Sqrt(math.Pow(this.Dx, 2.0) + math.Pow(this.Dy, 2.0))
+func (v Vector) Magnitude() float64 {
+	return math.Sqrt(math.Pow(v.Dx, 2.0) + math.Pow(v.Dy, 2.0))
 }
 
-func (this Vector) GetPolarAngle() float64 {
-	return math.Atan2(this.Dy, this.Dx)
+func (v Vector) GetPolarAngle() float64 {
+	return math.Atan2(v.Dy, v.Dx)
 }