Annotations support for rectangle and ellipses with appearance stream in annotator.

pdf/annotator/annotator.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package annotator
 
 import (
@@ -126,4 +131,50 @@ func CreateRectangleAnnotation(rectDef RectangleAnnotationDef) (*pdf.PdfAnnotati
 }
 
 type CircleAnnotationDef struct {
+	X             float64
+	Y             float64
+	Width         float64
+	Height        float64
+	FillEnabled   bool // Show fill?
+	FillColor     *pdf.PdfColorDeviceRGB
+	BorderEnabled bool // Show border?
+	BorderWidth   float64
+	BorderColor   *pdf.PdfColorDeviceRGB
+	Opacity       float64 // Alpha value (0-1).
+}
+
+// Creates a circle/ellipse annotation object with appearance stream that can be added to page PDF annotations.
+func CreateCircleAnnotation(circDef CircleAnnotationDef) (*pdf.PdfAnnotation, error) {
+	circAnnotation := pdf.NewPdfAnnotationCircle()
+
+	if circDef.BorderEnabled {
+		r, g, b := circDef.BorderColor.R(), circDef.BorderColor.G(), circDef.BorderColor.B()
+		circAnnotation.C = pdfcore.MakeArrayFromFloats([]float64{r, g, b})
+		bs := pdf.NewBorderStyle()
+		bs.SetBorderWidth(circDef.BorderWidth)
+		circAnnotation.BS = bs.ToPdfObject()
+	}
+
+	if circDef.FillEnabled {
+		r, g, b := circDef.FillColor.R(), circDef.FillColor.G(), circDef.FillColor.B()
+		circAnnotation.IC = pdfcore.MakeArrayFromFloats([]float64{r, g, b})
+	} else {
+		circAnnotation.IC = pdfcore.MakeArrayFromIntegers([]int{}) // No fill.
+	}
+
+	if circDef.Opacity < 1.0 {
+		circAnnotation.CA = pdfcore.MakeFloat(circDef.Opacity)
+	}
+
+	// Make the appearance stream (for uniform appearance).
+	apDict, bbox, err := makeCircleAnnotationAppearanceStream(circDef)
+	if err != nil {
+		return nil, err
+	}
+
+	circAnnotation.AP = apDict
+	circAnnotation.Rect = pdfcore.MakeArrayFromFloats([]float64{bbox.Llx, bbox.Lly, bbox.Urx, bbox.Ury})
+
+	return circAnnotation.PdfAnnotation, nil
+
 }

pdf/annotator/circle.go

@@ -0,0 +1,137 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
+package annotator
+
+import (
+	"github.com/unidoc/unidoc/common"
+
+	pdfcontent "github.com/unidoc/unidoc/pdf/contentstream"
+	"github.com/unidoc/unidoc/pdf/contentstream/draw"
+	pdfcore "github.com/unidoc/unidoc/pdf/core"
+	pdf "github.com/unidoc/unidoc/pdf/model"
+)
+
+// Make the bezier path with the content creator.
+func drawBezierPathWithCreator(bpath draw.CubicBezierPath, creator *pdfcontent.ContentCreator) {
+	for idx, c := range bpath.Curves {
+		if idx == 0 {
+			creator.Add_m(c.P0.X, c.P0.Y)
+		}
+		creator.Add_c(c.P1.X, c.P1.Y, c.P2.X, c.P2.Y, c.P3.X, c.P3.Y)
+	}
+}
+
+func makeCircleAnnotationAppearanceStream(circDef CircleAnnotationDef) (*pdfcore.PdfObjectDictionary, *pdf.PdfRectangle, error) {
+	form := pdf.NewXObjectForm()
+	form.Resources = pdf.NewPdfPageResources()
+
+	gsName := ""
+	if circDef.Opacity < 1.0 {
+		// Create graphics state with right opacity.
+		gsState := &pdfcore.PdfObjectDictionary{}
+		gsState.Set("ca", pdfcore.MakeFloat(circDef.Opacity))
+		gsState.Set("CA", pdfcore.MakeFloat(circDef.Opacity))
+		err := form.Resources.AddExtGState("gs1", gsState)
+		if err != nil {
+			common.Log.Debug("Unable to add extgstate gs1")
+			return nil, nil, err
+		}
+
+		gsName = "gs1"
+	}
+
+	content, localBbox, globalBbox, err := drawPdfCircle(circDef, gsName)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	err = form.SetContentStream(content, nil)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Local bounding box for the XObject Form.
+	form.BBox = localBbox.ToPdfObject()
+
+	apDict := &pdfcore.PdfObjectDictionary{}
+	apDict.Set("N", form.ToPdfObject())
+
+	return apDict, globalBbox, nil
+}
+
+func drawPdfCircle(circDef CircleAnnotationDef, gsName string) ([]byte, *pdf.PdfRectangle, *pdf.PdfRectangle, error) {
+	xRad := circDef.Width / 2
+	yRad := circDef.Height / 2
+	if circDef.BorderEnabled {
+		xRad -= circDef.BorderWidth / 2
+		yRad -= circDef.BorderWidth / 2
+	}
+
+	magic := 0.551784
+	xMagic := xRad * magic
+	yMagic := yRad * magic
+
+	bpath := draw.NewCubicBezierPath()
+	bpath = bpath.AppendCurve(draw.NewCubicBezierCurve(-xRad, 0, -xRad, yMagic, -xMagic, yRad, 0, yRad))
+	bpath = bpath.AppendCurve(draw.NewCubicBezierCurve(0, yRad, xMagic, yRad, xRad, yMagic, xRad, 0))
+	bpath = bpath.AppendCurve(draw.NewCubicBezierCurve(xRad, 0, xRad, -yMagic, xMagic, -yRad, 0, -yRad))
+	bpath = bpath.AppendCurve(draw.NewCubicBezierCurve(0, -yRad, -xMagic, -yRad, -xRad, -yMagic, -xRad, 0))
+	bpath = bpath.Offset(xRad, yRad)
+	if circDef.BorderEnabled {
+		bpath = bpath.Offset(circDef.BorderWidth/2, circDef.BorderWidth/2)
+	}
+
+	creator := pdfcontent.NewContentCreator()
+
+	creator.Add_q()
+
+	if circDef.FillEnabled {
+		creator.Add_rg(circDef.FillColor.R(), circDef.FillColor.G(), circDef.FillColor.B())
+	}
+	if circDef.BorderEnabled {
+		creator.Add_RG(circDef.BorderColor.R(), circDef.BorderColor.G(), circDef.BorderColor.B())
+		creator.Add_w(circDef.BorderWidth)
+	}
+	if len(gsName) > 1 {
+		// If a graphics state is provided, use it. (Used for transparency settings here).
+		creator.Add_gs(pdfcore.PdfObjectName(gsName))
+	}
+
+	drawBezierPathWithCreator(bpath, creator)
+
+	creator.Add_B() // fill and stroke.
+	creator.Add_Q()
+
+	// Offsets (needed for placement of annotations bbox).
+	offX := circDef.X
+	offY := circDef.Y
+
+	// Get bounding box.
+	pathBbox := bpath.GetBoundingBox()
+	if circDef.BorderEnabled {
+		// Account for stroke width.
+		pathBbox.Height += circDef.BorderWidth
+		pathBbox.Width += circDef.BorderWidth
+		pathBbox.X -= circDef.BorderWidth / 2
+		pathBbox.Y -= circDef.BorderWidth / 2
+	}
+
+	// Bounding box - local coordinate system (without offset).
+	localBbox := &pdf.PdfRectangle{}
+	localBbox.Llx = pathBbox.X
+	localBbox.Lly = pathBbox.Y
+	localBbox.Urx = pathBbox.X + pathBbox.Width
+	localBbox.Ury = pathBbox.Y + pathBbox.Height
+
+	// Bounding box - global page coordinate system (with offset).
+	globalBbox := &pdf.PdfRectangle{}
+	globalBbox.Llx = offX + pathBbox.X
+	globalBbox.Lly = offY + pathBbox.Y
+	globalBbox.Urx = offX + pathBbox.X + pathBbox.Width
+	globalBbox.Ury = offY + pathBbox.Y + pathBbox.Height
+
+	return creator.Bytes(), localBbox, globalBbox, nil
+}

pdf/annotator/line.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package annotator
 
 import (

pdf/annotator/rectangle.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package annotator
 
 import (

pdf/contentstream/draw/bezier_curve.go

@@ -0,0 +1,154 @@
+/*
+ * 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
+}

pdf/contentstream/draw/path.go

@@ -1,29 +1,11 @@
+/*
+ * 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 "fmt"
-
-type Point struct {
-	X float64
-	Y float64
-}
-
-func (p Point) Add(dx, dy float64) Point {
-	p.X += dx
-	p.Y += dy
-	return p
-}
-
-// 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) String() string {
-	return fmt.Sprintf("(%.1f,%.1f)", p.X, p.Y)
-}
-
+// A path consists of straight line connections between each point defined in an array of points.
 type Path struct {
 	Points []Point
 }
@@ -34,13 +16,6 @@ func NewPath() Path {
 	return path
 }
 
-func NewPoint(x, y float64) Point {
-	point := Point{}
-	point.X = x
-	point.Y = y
-	return point
-}
-
 func (this Path) AppendPoint(point Point) Path {
 	this.Points = append(this.Points, point)
 	return this

pdf/contentstream/draw/point.go

@@ -0,0 +1,37 @@
+/*
+ * 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 "fmt"
+
+type Point struct {
+	X float64
+	Y float64
+}
+
+func NewPoint(x, y float64) Point {
+	point := Point{}
+	point.X = x
+	point.Y = y
+	return point
+}
+
+func (p Point) Add(dx, dy float64) Point {
+	p.X += dx
+	p.Y += dy
+	return p
+}
+
+// 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) String() string {
+	return fmt.Sprintf("(%.1f,%.1f)", p.X, p.Y)
+}

pdf/contentstream/draw/vector.go

@@ -1,3 +1,8 @@
+/*
+ * 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"