contmeta: support super and subcript rendering in all renderers

Author: rcoreilly

paint/pdf/pdf_test.go

@@ -98,7 +98,7 @@ func TestText(t *testing.T) {
 		prv := UseStandardFonts()
 		sh := shaped.NewShaper()
 
-		src := "PDF can put <b>HTML</b> <br>formatted Text where you <i>want</i>"
+		src := "PDF can put <b>HTML</b> <br>formatted Text where you <i>want</i> <br>including<sup>1</sup> and sub<sub>script</sub>"
 		rsty := &sty.Font
 		tsty := &sty.Text
 

paint/pdf/text.go

@@ -122,7 +122,6 @@ func (r *PDF) textRunRegions(m math32.Matrix2, run *shapedgt.Run, ln *shaped.Lin
 func (r *PDF) textRun(style *styles.Paint, m math32.Matrix2, run *shapedgt.Run, ln *shaped.Line, lns *shaped.Lines, runes []rune, clr image.Image, off math32.Vector2) {
 	// dir := run.Direction
 	region := run.Runes()
-	offTrans := math32.Translate2D(off.X, off.Y)
 	rbb := run.MaxBounds.Translate(off)
 	fill := clr
 	if run.FillColor != nil {
@@ -131,14 +130,24 @@ func (r *PDF) textRun(style *styles.Paint, m math32.Matrix2, run *shapedgt.Run,
 	fsz := math32.FromFixed(run.Size)
 	lineW := max(fsz/16, 1) // 1 at 16, bigger if biggerr
 	if run.Math.Path != nil {
-		r.w.PushTransform(offTrans)
+		r.w.PushTransform(math32.Translate2D(off.X, off.Y))
 		psty := *style
 		psty.Stroke.Color = run.StrokeColor
 		psty.Fill.Color = fill
 		r.Path(*run.Math.Path, &psty, math32.Identity2())
 		r.w.PopStack()
 		return
 	}
+	sty := run.Font.Style(&style.Text)
+	// https://en.wikipedia.org/wiki/Subscript_and_superscript: latex does -.14 sub, .25 super
+	// others often use -.33 and .33
+	if sty.Special == rich.Super {
+		off.X += 0.05 * fsz // tends to be cramped otherwise
+		off.Y -= 0.25 * fsz
+	} else if sty.Special == rich.Sub {
+		off.X += 0.05 * fsz // tends to be cramped otherwise
+		off.Y += 0.14 * fsz
+	}
 
 	idm := math32.Identity2()
 	if run.Decoration.HasFlag(rich.Underline) || run.Decoration.HasFlag(rich.DottedUnderline) {
@@ -160,7 +169,7 @@ func (r *PDF) textRun(style *styles.Paint, m math32.Matrix2, run *shapedgt.Run,
 		}
 	}
 
-	r.w.StartTextObject(offTrans)
+	r.w.StartTextObject(math32.Translate2D(off.X, off.Y))
 	r.setTextStyle(&run.Font, style, fill, run.StrokeColor, math32.FromFixed(run.Size), lns.LineHeight)
 	raw := string(runes[region.Start:region.End])
 	r.w.WriteText(raw)

paint/renderers/htmlcanvas/text.go

@@ -120,6 +120,14 @@ func (rs *Renderer) TextRun(ctx *render.Context, run *shapedgt.Run, ln *shaped.L
 		rs.setTransform(ctx)
 		return
 	}
+	sty := run.Font.Style(&ctx.Style.Text)
+	// https://en.wikipedia.org/wiki/Subscript_and_superscript: latex does -.14 sub, .25 super
+	// others often use -.33 and .33
+	if sty.Special == rich.Super {
+		off.Y -= 0.25 * fsz
+	} else if sty.Special == rich.Sub {
+		off.Y += 0.14 * fsz
+	}
 
 	if run.Decoration.HasFlag(rich.Underline) || run.Decoration.HasFlag(rich.DottedUnderline) {
 		dash := []float32{2, 2}

paint/renderers/rasterx/text.go

@@ -131,6 +131,15 @@ func (rs *Renderer) TextRun(ctx *render.Context, run *shapedgt.Run, ln *shaped.L
 		return
 	}
 
+	sty := run.Font.Style(&ctx.Style.Text)
+	// https://en.wikipedia.org/wiki/Subscript_and_superscript: latex does -.14 sub, .25 super
+	// others often use -.33 and .33
+	if sty.Special == rich.Super {
+		off.Y -= 0.25 * fsz
+	} else if sty.Special == rich.Sub {
+		off.Y += 0.14 * fsz
+	}
+
 	if run.Decoration.HasFlag(rich.Underline) || run.Decoration.HasFlag(rich.DottedUnderline) {
 		dash := []float32{2, 2}
 		if run.Decoration.HasFlag(rich.Underline) {

text/shaped/shaped_test.go

@@ -415,3 +415,16 @@ func TestGlyphAlign(t *testing.T) {
 		pc.DrawText(lns, pos)
 	})
 }
+
+func TestGlyphSuperSub(t *testing.T) {
+	RunTest(t, "supersub", 300, 300, func(pc *paint.Painter, sh Shaper, tsty *text.Style) {
+		src := "Super<sup>script</sup> and Sub<sub>script</sub>"
+		sty := rich.NewStyle()
+		sty.Size = 0.845
+		tx, err := htmltext.HTMLToRich([]byte(src), sty, nil)
+		assert.NoError(t, err)
+		lns := sh.WrapLines(tx, sty, tsty, math32.Vec2(250, 250))
+		pos := math32.Vec2(10.3, 10.96875)
+		pc.DrawText(lns, pos)
+	})
+}