add pattern support

README.markdown

@@ -30,7 +30,7 @@ Output goes to the specified io.Writer.
 
 ### Metadata elements ###
 
- desc, defs, g (style, transform, id), marker, mask, title, (a)ddress, link, script, use
+ desc, defs, g (style, transform, id), marker, mask, pattern, title, (a)ddress, link, script, use
 
 ## Building and Usage ##
 
@@ -290,19 +290,28 @@ is used to specify inputs and results for filter effects
 	DefEnd()
   end a definition block.
 
-  Marker(id string, x, y, w, h int, s ...string)
+	Marker(id string, x, y, w, h int, s ...string)
   define a marker
+  <http://www.w3.org/TR/SVG11/painting.html#MarkerElement>
 
-  MarkerEnd()
+
+	MarkerEnd()
   end a marker
 
-	Mask(string, x int, y int, w int, h int, s ...string)
+
+	Mask(id string, x int, y int, w int, h int, s ...string)
   creates a mask with a specified id, dimension, and optional style.
   <http://www.w3.org/TR/SVG/masking.html>
 
 	MaskEnd()
   ends the Mask element.
 
+
+	Pattern(id string, x, y, width, height int, putype string, s ...string)
+ define a Pattern with the specified dimensions, the putype can be either "user" or "obj", which sets the patternUnits
+ attribute to be either userSpaceOnUse or objectBoundingBox.
+ <http://www.w3.org/TR/SVG11/pservers.html#Patterns>
+
 	Desc(s string)
   specify the text of the description.
   <http://www.w3.org/TR/SVG11/struct.html#DescElement>

doc.go

@@ -29,7 +29,7 @@ Filter Effects
 
 Metadata elements
 
- desc, defs, g (style, transform, id), mask, marker, title, (a)ddress, link, script, use
+ desc, defs, g (style, transform, id), mask, marker, pattern, title, (a)ddress, link, script, use
 
 Usage: (assuming GOPATH is set)
 

pattern/pattern.go

@@ -0,0 +1,33 @@
+// pattern: test the pattern function
+package main
+
+import (
+	"github.com/ajstarks/svgo"
+	"fmt"
+	"os"
+)
+
+func main() {
+	canvas := svg.New(os.Stdout)
+	w, h := 500, 500
+	pct := 5
+	pw, ph := (w*pct)/100, (h*pct)/100
+	canvas.Start(w, h)
+
+	// define the pattern
+	canvas.Def()
+	canvas.Pattern("hatch", 0, 0, pw, ph, "user")
+	canvas.Gstyle("fill:none;stroke-width:1")
+	canvas.Path(fmt.Sprintf("M0,0 l%d,%d", pw, ph), "stroke:red")
+	canvas.Path(fmt.Sprintf("M%d,0 l-%d,%d", pw, pw, ph), "stroke:blue")
+	canvas.Gend()
+	canvas.PatternEnd()
+	canvas.DefEnd()
+
+	// use the pattern
+	canvas.Gstyle("stroke:black; stroke-width:2")
+	canvas.Circle(w/2, h/2, h/8, "fill:url(#hatch)")
+	canvas.CenterRect((w*4)/5, h/2, h/4, h/4, "fill:url(#hatch)")
+	canvas.Gend()
+	canvas.End()
+}

svg.go

@@ -192,13 +192,32 @@ func (svg *SVG) Def() { svg.println(`<defs>`) }
 func (svg *SVG) DefEnd() { svg.println(`</defs>`) }
 
 // Marker defines a marker
+// Standard reference: http://www.w3.org/TR/SVG11/painting.html#MarkerElement
 func (svg *SVG) Marker(id string, x, y, width, height int, s ...string) {
-	svg.printf(`<marker id="%s" refX="%d" refY="%d" markerWidth="%d" markerHeight="%d" %s`, id, x, y, width, height, endstyle(s, ">\n"))
+	svg.printf(`<marker id="%s" refX="%d" refY="%d" markerWidth="%d" markerHeight="%d" %s`, 
+		id, x, y, width, height, endstyle(s, ">\n"))
 }
 
 // MarkEnd ends a marker
 func (svg *SVG) MarkerEnd() { svg.println(`</marker>`) }
 
+// Pattern defines a pattern with the specified dimensions.
+// The putype can be either "user" or "obj", which sets the patternUnits
+// attribute to be either userSpaceOnUse or objectBoundingBox
+// Standard reference: http://www.w3.org/TR/SVG11/pservers.html#Patterns
+func (svg *SVG) Pattern(id string, x, y, width, height int, putype string, s ...string) {
+	puattr := "userSpaceOnUse"
+	if putype != "user" {
+		puattr = "objectBoundingBox"
+	}
+	svg.printf(`<pattern id="%s" x="%d" y="%d" width="%d" height="%d" patternUnits="%s" %s`, 
+		id, x, y, width, height, puattr, endstyle(s, ">\n"))
+}
+
+// PatternEnd ends a marker
+func (svg *SVG) PatternEnd() { svg.println(`</pattern>`) }
+
+
 // Desc specified the text of the description tag.
 // Standard Reference: http://www.w3.org/TR/SVG11/struct.html#DescElement
 func (svg *SVG) Desc(s string) { svg.tt("desc", s) }

svgdef/svgdef.go

@@ -413,6 +413,7 @@ func defobjects(w, h int) {
 			"ClipPath(s ...string)/ClipEnd()",
 			"Def()/DefEnd()",
 			"Marker()/MarkerEnd()",
+			"Pattern()/PatternEnd()",
 			"Desc(s string)",
 			"Title(s string)",
 			"Script(type, data ...string)",
@@ -431,6 +432,7 @@ func defobjects(w, h int) {
 			"begin/end clip path",
 			"begin/end a defintion block",
 			"begin/end markers",
+			"begin/end pattern",
 			"set the description element",
 			"set the title element",
 			"define a script",