plot: properly handle descent in axis labels glyph boxes

.github/workflows/golangci-lint.yml

@@ -18,3 +18,4 @@ jobs:
           # Required: the version of golangci-lint is required and must be specified without patch version:
           # we always use the latest patch version.
           version: v1.34
+          args: --timeout=5m

axis.go

@@ -295,15 +295,41 @@ func (a horizontalAxis) draw(c draw.Canvas) {
 }
 
 // GlyphBoxes returns the GlyphBoxes for the tick labels.
-func (a horizontalAxis) GlyphBoxes(*Plot) []GlyphBox {
-	var boxes []GlyphBox
-	for _, t := range a.Tick.Marker.Ticks(a.Min, a.Max) {
+func (a horizontalAxis) GlyphBoxes(p *Plot) []GlyphBox {
+	var (
+		boxes []GlyphBox
+		yoff  font.Length
+	)
+
+	if a.Label.Text != "" {
+		x := a.Norm(p.X.Max)
+		switch a.Label.Position {
+		case draw.PosCenter:
+			x = a.Norm(0.5 * (p.X.Max + p.X.Min))
+		case draw.PosRight:
+			x -= a.Norm(0.5 * a.Label.TextStyle.Width(a.Label.Text).Points()) // FIXME(sbinet): want data coordinates
+		}
+		descent := a.Label.TextStyle.FontExtents().Descent
+		boxes = append(boxes, GlyphBox{
+			X:         x,
+			Rectangle: a.Label.TextStyle.Rectangle(a.Label.Text).Add(vg.Point{Y: yoff + descent}),
+		})
+		yoff += a.Label.TextStyle.Height(a.Label.Text)
+		yoff += a.Label.Padding
+	}
+
+	var (
+		marks   = a.Tick.Marker.Ticks(a.Min, a.Max)
+		height  = tickLabelHeight(a.Tick.Label, marks)
+		descent = a.Tick.Label.FontExtents().Descent
+	)
+	for _, t := range marks {
 		if t.IsMinor() {
 			continue
 		}
 		box := GlyphBox{
 			X:         a.Norm(t.Value),
-			Rectangle: a.Tick.Label.Rectangle(t.Label),
+			Rectangle: a.Tick.Label.Rectangle(t.Label).Add(vg.Point{Y: yoff + height + descent}),
 		}
 		boxes = append(boxes, box)
 	}
@@ -396,15 +422,50 @@ func (a verticalAxis) draw(c draw.Canvas) {
 }
 
 // GlyphBoxes returns the GlyphBoxes for the tick labels
-func (a verticalAxis) GlyphBoxes(*Plot) []GlyphBox {
-	var boxes []GlyphBox
-	for _, t := range a.Tick.Marker.Ticks(a.Min, a.Max) {
+func (a verticalAxis) GlyphBoxes(p *Plot) []GlyphBox {
+	var (
+		boxes []GlyphBox
+		xoff  font.Length
+	)
+
+	if a.Label.Text != "" {
+		yoff := a.Norm(p.Y.Max)
+		switch a.Label.Position {
+		case draw.PosCenter:
+			yoff = a.Norm(0.5 * (p.Y.Max + p.Y.Min))
+		case draw.PosTop:
+			yoff -= a.Norm(0.5 * a.Label.TextStyle.Width(a.Label.Text).Points()) // FIXME(sbinet): want data coordinates
+		}
+
+		sty := a.Label.TextStyle
+		sty.Rotation += math.Pi / 2
+
+		xoff += a.Label.TextStyle.Height(a.Label.Text)
+		descent := a.Label.TextStyle.FontExtents().Descent
+		boxes = append(boxes, GlyphBox{
+			Y:         yoff,
+			Rectangle: sty.Rectangle(a.Label.Text).Add(vg.Point{X: xoff - descent}),
+		})
+		xoff += descent
+		xoff += a.Label.Padding
+	}
+
+	marks := a.Tick.Marker.Ticks(a.Min, a.Max)
+	if w := tickLabelWidth(a.Tick.Label, marks); len(marks) != 0 && w > 0 {
+		xoff += w
+	}
+
+	var (
+		ext  = a.Tick.Label.FontExtents()
+		desc = ext.Height - ext.Ascent // descent + linegap
+	)
+	for _, t := range marks {
 		if t.IsMinor() {
 			continue
 		}
 		box := GlyphBox{
 			Y:         a.Norm(t.Value),
-			Rectangle: a.Tick.Label.Rectangle(t.Label),
+			Rectangle: a.Tick.Label.Rectangle(t.Label).Add(vg.Point{X: xoff, Y: desc}),
 		}
 		boxes = append(boxes, box)
 	}

legend.go

@@ -108,7 +108,7 @@ func (l *Legend) Draw(c draw.Canvas) {
 
 	descent := sty.FontExtents().Descent
 	enth := l.entryHeight()
-	y := c.Max.Y - enth
+	y := c.Max.Y - enth - descent
 	if !l.Top {
 		y = c.Min.Y + (enth+l.Padding)*(vg.Length(len(l.entries))-1)
 	}

plot.go

@@ -147,11 +147,13 @@ func (p *Plot) Draw(c draw.Canvas) {
 		c.SetColor(p.BackgroundColor)
 		c.Fill(c.Rectangle.Path())
 	}
+
 	if p.Title.Text != "" {
 		descent := p.Title.TextStyle.FontExtents().Descent
 		c.FillText(p.Title.TextStyle, vg.Point{X: c.Center().X, Y: c.Max.Y + descent}, p.Title.Text)
-		_, h, d := p.Title.TextStyle.Handler.Box(p.Title.Text, p.Title.TextStyle.Font)
-		c.Max.Y -= h + d
+
+		rect := p.Title.TextStyle.Rectangle(p.Title.Text)
+		c.Max.Y -= rect.Size().Y
 		c.Max.Y -= p.Title.Padding
 	}
 
@@ -179,7 +181,8 @@ func (p *Plot) Draw(c draw.Canvas) {
 // the plot data will be drawn.
 func (p *Plot) DataCanvas(da draw.Canvas) draw.Canvas {
 	if p.Title.Text != "" {
-		da.Max.Y -= p.Title.TextStyle.Height(p.Title.Text) + p.Title.TextStyle.FontExtents().Descent
+		rect := p.Title.TextStyle.Rectangle(p.Title.Text)
+		da.Max.Y -= rect.Size().Y
 		da.Max.Y -= p.Title.Padding
 	}
 	p.X.sanitizeRange()
@@ -191,12 +194,61 @@ func (p *Plot) DataCanvas(da draw.Canvas) draw.Canvas {
 
 // DrawGlyphBoxes draws red outlines around the plot's
 // GlyphBoxes.  This is intended for debugging.
-func (p *Plot) DrawGlyphBoxes(c *draw.Canvas) {
-	c.SetColor(color.RGBA{R: 255, A: 255})
+func (p *Plot) DrawGlyphBoxes(c draw.Canvas) {
+	dac := p.DataCanvas(c)
+	sty := draw.LineStyle{
+		Color: color.RGBA{R: 255, A: 255},
+		Width: vg.Points(0.5),
+	}
+
+	drawBox := func(c draw.Canvas, b GlyphBox) {
+		x := c.X(b.X) + b.Rectangle.Min.X
+		y := c.Y(b.Y) + b.Rectangle.Min.Y
+		c.StrokeLines(sty, []vg.Point{
+			{X: x, Y: y},
+			{X: x + b.Rectangle.Size().X, Y: y},
+			{X: x + b.Rectangle.Size().X, Y: y + b.Rectangle.Size().Y},
+			{X: x, Y: y + b.Rectangle.Size().Y},
+			{X: x, Y: y},
+		})
+	}
+
+	var title vg.Length
+	if p.Title.Text != "" {
+		rect := p.Title.TextStyle.Rectangle(p.Title.Text)
+		title += rect.Size().Y
+		title += p.Title.Padding
+		box := GlyphBox{
+			Rectangle: rect.Add(vg.Point{
+				X: c.Center().X,
+				Y: c.Max.Y,
+			}),
+		}
+		drawBox(c, box)
+	}
+
 	for _, b := range p.GlyphBoxes(p) {
-		b.Rectangle.Min.X += c.X(b.X)
-		b.Rectangle.Min.Y += c.Y(b.Y)
-		c.Stroke(b.Rectangle.Path())
+		drawBox(dac, b)
+	}
+
+	p.X.sanitizeRange()
+	p.Y.sanitizeRange()
+
+	x := horizontalAxis{p.X}
+	y := verticalAxis{p.Y}
+
+	ywidth := y.size()
+	xheight := x.size()
+
+	cx := padX(p, draw.Crop(c, ywidth, 0, 0, 0))
+	for _, b := range x.GlyphBoxes(p) {
+		drawBox(cx, b)
+	}
+
+	cy := padY(p, draw.Crop(c, 0, 0, xheight, 0))
+	cy.Max.Y -= title
+	for _, b := range y.GlyphBoxes(p) {
+		drawBox(cy, b)
 	}
 }
 

plot_test.go

@@ -128,3 +128,63 @@ func TestIssue514(t *testing.T) {
 		})
 	}
 }
+
+func TestDrawGlyphBoxes(t *testing.T) {
+	cmpimg.CheckPlot(func() {
+		p := plot.New()
+
+		p.Title.Text = "My very very very\nlong Title"
+		p.X.Min = 0
+		p.X.Max = 10
+		p.Y.Min = 0
+		p.Y.Max = 10
+
+		p.X.Label.Text = "X-axis"
+		p.Y.Label.Text = "Y-axis"
+
+		f1 := plotter.NewFunction(func(x float64) float64 { return 5 })
+		f1.LineStyle.Color = color.RGBA{R: 255, A: 255}
+
+		f2 := plotter.NewFunction(func(x float64) float64 { return 6 })
+		f2.LineStyle.Color = color.RGBA{B: 255, A: 255}
+
+		labels, err := plotter.NewLabels(plotter.XYLabels{
+			XYs: []plotter.XY{
+				{X: 2.5, Y: 2.5},
+				{X: 7.5, Y: 2.5},
+				{X: 7.5, Y: 7.5},
+				{X: 2.5, Y: 7.5},
+			},
+			Labels: []string{"Agg", "Bgg", "Cgg", "Dgg"},
+		})
+		if err != nil {
+			t.Fatalf("could not creates labels plotter: %+v", err)
+		}
+
+		p.Add(f1, f2, labels)
+		p.Add(plotter.NewGrid())
+
+		p.Legend.Add("fg1", f1)
+		p.Legend.Add("fg2", f2)
+		p.Legend.Top = true
+
+		c := vgimg.PngCanvas{
+			Canvas: vgimg.New(20*vg.Centimeter, 15*vg.Centimeter),
+		}
+
+		d := draw.New(c)
+		p.Draw(d)
+		p.DrawGlyphBoxes(d)
+
+		buf := new(bytes.Buffer)
+		_, err = c.WriteTo(buf)
+		if err != nil {
+			t.Fatalf("error: %+v", err)
+		}
+
+		err = ioutil.WriteFile("testdata/glyphbox.png", buf.Bytes(), 0644)
+		if err != nil {
+			t.Fatalf("could not save plot: %+v", err)
+		}
+	}, t, "glyphbox.png")
+}

plotter/testdata/polygon_holes_golden.eps

@@ -2,7 +2,7 @@
 %%Creator gonum.org/v1/plot/vg/vgeps
 %%Title: 
 %%BoundingBox: 0 0 100 100
-%%CreationDate: 2021-01-13 19:18:09.973243623 +0100 CET m=+3.699589445
+%%CreationDate: 2021-08-04 15:18:17.591742993 +0200 CEST m=+1.847419518
 %%Orientation: Portrait
 %%EndComments
 
@@ -57,79 +57,79 @@ stroke
 gsave
 90 rotate
 /LiberationSerif-Regular findfont 12 scalefont setfont
-57.652 -9.3867 moveto
+56.358 -9.3867 moveto
 (Y) show
 grestore
 15.885 37.924 moveto
 (0) show
-15.885 59.7 moveto
+15.885 58.406 moveto
 (2) show
-15.885 81.477 moveto
+15.885 78.889 moveto
 (4) show
 newpath
 23.385 40.209 moveto
 31.385 40.209 lineto
 stroke
 newpath
-23.385 61.985 moveto
-31.385 61.985 lineto
+23.385 60.691 moveto
+31.385 60.691 lineto
 stroke
 newpath
-23.385 83.762 moveto
-31.385 83.762 lineto
+23.385 81.174 moveto
+31.385 81.174 lineto
 stroke
 newpath
-27.385 51.097 moveto
-31.385 51.097 lineto
+27.385 50.45 moveto
+31.385 50.45 lineto
 stroke
 newpath
-27.385 72.874 moveto
-31.385 72.874 lineto
+27.385 70.933 moveto
+31.385 70.933 lineto
 stroke
 newpath
 31.385 40.209 moveto
-31.385 83.762 lineto
+31.385 81.174 lineto
 stroke
 0 0 1 setrgbcolor
 newpath
 37.135 40.209 moveto
 97.5 40.209 lineto
-97.5 83.762 lineto
-37.135 83.762 lineto
+97.5 81.174 lineto
+37.135 81.174 lineto
 closepath
-44.68 45.653 moveto
-59.772 45.653 lineto
-59.772 56.541 lineto
-44.68 56.541 lineto
+44.68 45.33 moveto
+59.772 45.33 lineto
+59.772 55.571 lineto
+44.68 55.571 lineto
 closepath
-89.954 67.429 moveto
-74.863 67.429 lineto
-74.863 78.318 lineto
-89.954 78.318 lineto
+89.954 65.812 moveto
+74.863 65.812 lineto
+74.863 76.053 lineto
+89.954 76.053 lineto
 closepath
 fill
 0 0 0 setrgbcolor
 1 setlinewidth
 newpath
 37.135 40.209 moveto
 97.5 40.209 lineto
-97.5 83.762 lineto
-37.135 83.762 lineto
+97.5 81.174 lineto
+37.135 81.174 lineto
 37.135 40.209 lineto
 stroke
 newpath
-44.68 45.653 moveto
-59.772 45.653 lineto
-59.772 56.541 lineto
-44.68 56.541 lineto
-44.68 45.653 lineto
+44.68 45.33 moveto
+59.772 45.33 lineto
+59.772 55.571 lineto
+44.68 55.571 lineto
+44.68 45.33 lineto
 stroke
 newpath
-89.954 67.429 moveto
-74.863 67.429 lineto
-74.863 78.318 lineto
-89.954 78.318 lineto
-89.954 67.429 lineto
+89.954 65.812 moveto
+74.863 65.812 lineto
+74.863 76.053 lineto
+89.954 76.053 lineto
+89.954 65.812 lineto
 stroke
 0 0 1 setrgbcolor
 newpath