Add partial support for spot colors. This does not yet include gradients, etc

1 files changed, 184 insertions, 0 deletions

diff --git a/spotcolor.go b/spotcolor.go
new file mode 100644
index 0000000..33aca82
--- /dev/null
+++ b/spotcolor.go
@@ -0,0 +1,184 @@
+// Copyright (c) Kurt Jung (Gmail: kurt.w.jung)
+//
+// Permission to use, copy, modify, and distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+// Adapted from http://www.fpdf.org/en/script/script89.php by Olivier PLATHEY
+
+package gofpdf
+
+import (
+	"fmt"
+	"strings"
+)
+
+func byteBound(v byte) byte {
+	if v > 100 {
+		return 100
+	}
+	return v
+}
+
+// AddSpotColor adds an ink-based CMYK color to the gofpdf instance and
+// associates it with the specified name. The individual components specify
+// percentages ranging from 0 to 100. Values above this are quietly capped to
+// 100. An error occurs if the specified name is already associated with a
+// color.
+func (f *Fpdf) AddSpotColor(nameStr string, c, m, y, k byte) {
+	if f.err == nil {
+		_, ok := f.spotColorMap[nameStr]
+		if !ok {
+			id := len(f.spotColorMap) + 1
+			f.spotColorMap[nameStr] = spotColorType{
+				id: id,
+				val: cmykColorType{
+					c: byteBound(c),
+					m: byteBound(m),
+					y: byteBound(y),
+					k: byteBound(k),
+				},
+			}
+		} else {
+			f.err = fmt.Errorf("name \"%s\" is already associated with a spot color", nameStr)
+		}
+	}
+}
+
+func (f *Fpdf) getSpotColor(nameStr string) (clr spotColorType, ok bool) {
+	if f.err == nil {
+		clr, ok = f.spotColorMap[nameStr]
+		if !ok {
+			f.err = fmt.Errorf("spot color name \"%s\" is not registered", nameStr)
+		}
+	}
+	return
+}
+
+// SetDrawSpotColor sets the current draw color to the spot color associated
+// with nameStr. An error occurs if the name is not associated with a color.
+// The value for tint ranges from 0 (no intensity) to 100 (full intensity). It
+// is quietly bounded to this range.
+func (f *Fpdf) SetDrawSpotColor(nameStr string, tint byte) {
+	var clr spotColorType
+	var ok bool
+
+	clr, ok = f.getSpotColor(nameStr)
+	if ok {
+		f.color.draw.mode = colorModeSpot
+		f.color.draw.spotStr = nameStr
+		f.color.draw.str = sprintf("/CS%d CS %.3f SCN", clr.id, float64(byteBound(tint))/100)
+		if f.page > 0 {
+			f.out(f.color.draw.str)
+		}
+	}
+}
+
+// SetFillSpotColor sets the current fill color to the spot color associated
+// with nameStr. An error occurs if the name is not associated with a color.
+// The value for tint ranges from 0 (no intensity) to 100 (full intensity). It
+// is quietly bounded to this range.
+func (f *Fpdf) SetFillSpotColor(nameStr string, tint byte) {
+	var clr spotColorType
+	var ok bool
+
+	clr, ok = f.getSpotColor(nameStr)
+	if ok {
+		f.color.fill.mode = colorModeSpot
+		f.color.fill.spotStr = nameStr
+		f.color.fill.str = sprintf("/CS%d cs %.3f scn", clr.id, float64(byteBound(tint))/100)
+		f.colorFlag = f.color.fill.str != f.color.text.str
+		if f.page > 0 {
+			f.out(f.color.fill.str)
+		}
+	}
+}
+
+// SetTextSpotColor sets the current text color to the spot color associated
+// with nameStr. An error occurs if the name is not associated with a color.
+// The value for tint ranges from 0 (no intensity) to 100 (full intensity). It
+// is quietly bounded to this range.
+func (f *Fpdf) SetTextSpotColor(nameStr string, tint byte) {
+	var clr spotColorType
+	var ok bool
+
+	clr, ok = f.getSpotColor(nameStr)
+	if ok {
+		f.color.text.mode = colorModeSpot
+		f.color.text.spotStr = nameStr
+		f.color.text.str = sprintf("/CS%d cs %.3f scn", clr.id, float64(byteBound(tint))/100)
+		f.colorFlag = f.color.text.str != f.color.text.str
+	}
+}
+
+func (f *Fpdf) returnSpotColor(clr colorType) (name string, c, m, y, k byte) {
+	var spotClr spotColorType
+	var ok bool
+
+	name = clr.spotStr
+	if name != "" {
+		spotClr, ok = f.getSpotColor(name)
+		if ok {
+			c = spotClr.val.c
+			m = spotClr.val.m
+			y = spotClr.val.y
+			k = spotClr.val.k
+		}
+	}
+	return
+}
+
+// GetDrawSpotColor returns the most recently used spot color information for
+// drawing. This will not be the current drawing color if some other color type
+// such as RGB is active. If no spot color has been set for drawing, zero
+// values are returned.
+func (f *Fpdf) GetDrawSpotColor() (name string, c, m, y, k byte) {
+	return f.returnSpotColor(f.color.draw)
+}
+
+// GetTextSpotColor returns the most recently used spot color information for
+// text output. This will not be the current text color if some other color
+// type such as RGB is active. If no spot color has been set for text, zero
+// values are returned.
+func (f *Fpdf) GetTextSpotColor() (name string, c, m, y, k byte) {
+	return f.returnSpotColor(f.color.text)
+}
+
+// GetFillSpotColor returns the most recently used spot color information for
+// fill output. This will not be the current fill color if some other color
+// type such as RGB is active. If no fill spot color has been set, zero values
+// are returned.
+func (f *Fpdf) GetFillSpotColor() (name string, c, m, y, k byte) {
+	return f.returnSpotColor(f.color.fill)
+}
+
+func (f *Fpdf) putSpotColors() {
+	for k, v := range f.spotColorMap {
+		f.newobj()
+		f.outf("[/Separation /%s", strings.Replace(k, " ", "#20", -1))
+		f.out("/DeviceCMYK <<")
+		f.out("/Range [0 1 0 1 0 1 0 1] /C0 [0 0 0 0] ")
+		f.outf("/C1 [%.3f %.3f %.3f %.3f] ", float64(v.val.c)/100, float64(v.val.m)/100,
+			float64(v.val.y)/100, float64(v.val.k)/100)
+		f.out("/FunctionType 2 /Domain [0 1] /N 1>>]")
+		f.out("endobj")
+		v.objID = f.n
+		f.spotColorMap[k] = v
+	}
+}
+
+func (f *Fpdf) spotColorPutResourceDict() {
+	f.out("/ColorSpace <<")
+	for _, clr := range f.spotColorMap {
+		f.outf("/CS%d %d 0 R", clr.id, clr.objID)
+	}
+	f.out(">>")
+}