widget{,/material}: surface line height manipulation

This commit surfaces fields to manipulate the line height of all label and editor
types. It's unfortunate how this spreads through the API, but I don't see a good
way to eliminate that right now.

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

widget/material/editor.go

@@ -16,8 +16,14 @@ import (
 )
 
 type EditorStyle struct {
-	Font     font.Font
-	TextSize unit.Sp
+	Font font.Font
+	// LineHeight controls the distance between the baselines of lines of text.
+	// If zero, a sensible default will be used.
+	LineHeight unit.Sp
+	// LineHeightScale applies a scaling factor to the LineHeight. If zero, a
+	// sensible default will be used.
+	LineHeightScale float32
+	TextSize        unit.Sp
 	// Color is the text color.
 	Color color.NRGBA
 	// Hint contains the text displayed when the editor is empty.
@@ -64,7 +70,12 @@ func (e EditorStyle) Layout(gtx layout.Context) layout.Dimensions {
 	}
 
 	macro := op.Record(gtx.Ops)
-	tl := widget.Label{Alignment: e.Editor.Alignment, MaxLines: maxlines}
+	tl := widget.Label{
+		Alignment:       e.Editor.Alignment,
+		MaxLines:        maxlines,
+		LineHeight:      e.LineHeight,
+		LineHeightScale: e.LineHeightScale,
+	}
 	dims := tl.Layout(gtx, e.shaper, e.Font, e.TextSize, e.Hint, hintColor)
 	call := macro.Stop()
 
@@ -74,6 +85,8 @@ func (e EditorStyle) Layout(gtx layout.Context) layout.Dimensions {
 	if h := dims.Size.Y; gtx.Constraints.Min.Y < h {
 		gtx.Constraints.Min.Y = h
 	}
+	e.Editor.LineHeight = e.LineHeight
+	e.Editor.LineHeightScale = e.LineHeightScale
 	dims = e.Editor.Layout(gtx, e.shaper, e.Font, e.TextSize, textColor, selectionColor)
 	if e.Editor.Len() == 0 {
 		call.Add(gtx.Ops)

widget/material/label.go

@@ -38,6 +38,12 @@ type LabelStyle struct {
 	Text string
 	// TextSize determines the size of the text glyphs.
 	TextSize unit.Sp
+	// LineHeight controls the distance between the baselines of lines of text.
+	// If zero, a sensible default will be used.
+	LineHeight unit.Sp
+	// LineHeightScale applies a scaling factor to the LineHeight. If zero, a
+	// sensible default will be used.
+	LineHeightScale float32
 
 	// Shaper is the text shaper used to display this labe. This field is automatically
 	// set using by all constructor functions. If constructing a LabelStyle literal, you
@@ -132,13 +138,17 @@ func (l LabelStyle) Layout(gtx layout.Context) layout.Dimensions {
 		l.State.MaxLines = l.MaxLines
 		l.State.Truncator = l.Truncator
 		l.State.WrapPolicy = l.WrapPolicy
+		l.State.LineHeight = l.LineHeight
+		l.State.LineHeightScale = l.LineHeightScale
 		return l.State.Layout(gtx, l.Shaper, l.Font, l.TextSize, textColor, selectColor)
 	}
 	tl := widget.Label{
-		Alignment:  l.Alignment,
-		MaxLines:   l.MaxLines,
-		Truncator:  l.Truncator,
-		WrapPolicy: l.WrapPolicy,
+		Alignment:       l.Alignment,
+		MaxLines:        l.MaxLines,
+		Truncator:       l.Truncator,
+		WrapPolicy:      l.WrapPolicy,
+		LineHeight:      l.LineHeight,
+		LineHeightScale: l.LineHeightScale,
 	}
 	return tl.Layout(gtx, l.Shaper, l.Font, l.TextSize, l.Text, textColor)
 }