text,vg/draw: use vg.Canvas in TextHandler interface

gonum · Jan 29, 2021 · 61a5e05 · 61a5e05
1 parent a02d161
commit 61a5e05
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Showing 3 changed files with 22 additions and 5 deletions.
diff --git a/text/latex.go b/text/latex.go
@@ -6,6 +6,7 @@ package text
 
 import (
 	"fmt"
+	"image/color"
 	"math"
 	"strings"
 
@@ -73,7 +74,7 @@ func (hdlr Latex) Box(txt string, fnt vg.Font) (width, height, depth vg.Length)
 
 // Draw renders the given text with the provided style and position
 // on the canvas.
-func (hdlr Latex) Draw(c *draw.Canvas, txt string, sty draw.TextStyle, pt vg.Point) {
+func (hdlr Latex) Draw(c vg.Canvas, txt string, sty draw.TextStyle, pt vg.Point) {
 	cnv := drawtex.New()
 	fnts := &ttf.Fonts{
 		Rm:      sty.Font.Font(),
@@ -135,7 +136,7 @@ func (hdlr Latex) dpi() float64 {
 }
 
 type latex struct {
-	cnv *draw.Canvas
+	cnv vg.Canvas
 	sty draw.TextStyle
 	pt  vg.Point
 
@@ -204,11 +205,27 @@ func (r *latex) drawRect(dpi float64, op drawtex.RectOp) {
 		vg.Point{X: x1, Y: y1}.Add(pt),
 	}
 
-	r.cnv.FillPolygon(r.sty.Color, pts)
+	fillPolygon(r.cnv, r.sty.Color, pts)
 }
 
 func (r *latex) rotate(x, y vg.Length) (vg.Length, vg.Length) {
 	u := x*r.cos + y*r.sin
 	v := y*r.cos - x*r.sin
 	return u, v
 }
+
+// FillPolygon fills a polygon with the given color.
+func fillPolygon(c vg.Canvas, clr color.Color, pts []vg.Point) {
+	if len(pts) == 0 {
+		return
+	}
+
+	c.SetColor(clr)
+	p := make(vg.Path, 0, len(pts)+1)
+	p.Move(pts[0])
+	for _, pt := range pts[1:] {
+		p.Line(pt)
+	}
+	p.Close()
+	c.Fill(p)
+}
diff --git a/vg/draw/text.go b/vg/draw/text.go
@@ -24,7 +24,7 @@ type TextHandler interface {
 
 	// Draw renders the given text with the provided style and position
 	// on the canvas.
-	Draw(c *Canvas, txt string, sty TextStyle, pt vg.Point)
+	Draw(c vg.Canvas, txt string, sty TextStyle, pt vg.Point)
 }
 
 // TextStyle describes what text will look like.

diff --git a/vg/draw/text_plain.go b/vg/draw/text_plain.go
@@ -37,7 +37,7 @@ func (hdlr PlainTextHandler) Box(txt string, fnt vg.Font) (width, height, depth
 
 // Draw renders the given text with the provided style and position
 // on the canvas.
-func (hdlr PlainTextHandler) Draw(c *Canvas, txt string, sty TextStyle, pt vg.Point) {
+func (hdlr PlainTextHandler) Draw(c vg.Canvas, txt string, sty TextStyle, pt vg.Point) {
 	txt = strings.TrimRight(txt, "\n")
 	if len(txt) == 0 {
 		return