text,widget{,/material}: [API] move all shaping parameters into text.Parameters

This commit moves the min/max width of shaped text and the text's Locale into
text.Parameters. They were previously passed as separate function parameters to
the shaper, but this made little sense and added visual noise. This is a breaking
change, but only if you previously invoked the shaping API directly.

Callers of text.(*Shaper).LayoutString should change:

    shaper.LayoutString(params, minWidth, maxWidth, locale, "string")

to

    params.MinWidth=minWidth
    params.MaxWidth=maxWidth
    params.Locale=locale
    shaper.LayoutString(params, "string")

Callers of text.(*Shaper).Layout should do likewise.

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

widget/text.go

@@ -10,7 +10,6 @@ import (
 	"unicode/utf8"
 
 	"gioui.org/f32"
-	"gioui.org/io/system"
 	"gioui.org/layout"
 	"gioui.org/op"
 	"gioui.org/op/clip"
@@ -58,22 +57,20 @@ type textView struct {
 	// are accessed by Len, Text, and SetText.
 	Mask rune
 
-	font       text.Font
+	params     text.Parameters
 	shaper     *text.Shaper
-	textSize   fixed.Int26_6
 	seekCursor int64
 	rr         textSource
 	maskReader maskReader
 	// graphemes tracks the indices of grapheme cluster boundaries within rr.
 	graphemes []int
 	// paragraphReader is used to populate graphemes.
-	paragraphReader    graphemeReader
-	lastMask           rune
-	maxWidth, minWidth int
-	viewSize           image.Point
-	valid              bool
-	regions            []Region
-	dims               layout.Dimensions
+	paragraphReader graphemeReader
+	lastMask        rune
+	viewSize        image.Point
+	valid           bool
+	regions         []Region
+	dims            layout.Dimensions
 
 	// offIndex is an index of rune index to byte offsets.
 	offIndex []offEntry
@@ -93,8 +90,6 @@ type textView struct {
 	}
 
 	scrollOff image.Point
-
-	locale system.Locale
 }
 
 func (e *textView) Changed() bool {
@@ -228,27 +223,27 @@ func (e *textView) calculateViewSize(gtx layout.Context) image.Point {
 // allow parent widgets to adapt to any changes in text content or positioning. If eventHandling modifies the contents
 // of the textView, it is guaranteed to be reshaped (and ready for painting) before Update returns.
 func (e *textView) Update(gtx layout.Context, lt *text.Shaper, font text.Font, size unit.Sp, eventHandling func(gtx layout.Context)) {
-	if e.locale != gtx.Locale {
-		e.locale = gtx.Locale
+	if e.params.Locale != gtx.Locale {
+		e.params.Locale = gtx.Locale
 		e.invalidate()
 	}
 	textSize := fixed.I(gtx.Sp(size))
-	if e.font != font || e.textSize != textSize {
+	if e.params.Font != font || e.params.PxPerEm != textSize {
 		e.invalidate()
-		e.font = font
-		e.textSize = textSize
+		e.params.Font = font
+		e.params.PxPerEm = textSize
 	}
 	maxWidth := gtx.Constraints.Max.X
 	if e.SingleLine {
 		maxWidth = math.MaxInt
 	}
 	minWidth := gtx.Constraints.Min.X
-	if maxWidth != e.maxWidth {
-		e.maxWidth = maxWidth
+	if maxWidth != e.params.MaxWidth {
+		e.params.MaxWidth = maxWidth
 		e.invalidate()
 	}
-	if minWidth != e.minWidth {
-		e.minWidth = minWidth
+	if minWidth != e.params.MinWidth {
+		e.params.MinWidth = minWidth
 		e.invalidate()
 	}
 	if lt != e.shaper {
@@ -259,6 +254,18 @@ func (e *textView) Update(gtx layout.Context, lt *text.Shaper, font text.Font, s
 		e.lastMask = e.Mask
 		e.invalidate()
 	}
+	if e.Alignment != e.params.Alignment {
+		e.params.Alignment = e.Alignment
+		e.invalidate()
+	}
+	if e.Truncator != e.params.Truncator {
+		e.params.Truncator = e.Truncator
+		e.invalidate()
+	}
+	if e.MaxLines != e.params.MaxLines {
+		e.params.MaxLines = e.MaxLines
+		e.invalidate()
+	}
 
 	e.makeValid()
 	if eventHandling != nil {
@@ -463,13 +470,7 @@ func (e *textView) layoutText(lt *text.Shaper) {
 	e.index.reset()
 	it := textIterator{viewport: image.Rectangle{Max: image.Point{X: math.MaxInt, Y: math.MaxInt}}}
 	if lt != nil {
-		lt.Layout(text.Parameters{
-			Font:      e.font,
-			PxPerEm:   e.textSize,
-			Alignment: e.Alignment,
-			MaxLines:  e.MaxLines,
-			Truncator: e.Truncator,
-		}, e.minWidth, e.maxWidth, e.locale, r)
+		lt.Layout(e.params, r)
 		for glyph, ok := it.processGlyph(lt.NextGlyph()); ok; glyph, ok = it.processGlyph(lt.NextGlyph()) {
 			e.index.Glyph(glyph)
 		}
@@ -635,7 +636,7 @@ func (e *textView) MoveEnd(selAct selectionAction) {
 	caret := e.closestToRune(e.caret.start)
 	caret = e.closestToLineCol(caret.lineCol.line, math.MaxInt)
 	e.caret.start = caret.runes
-	e.caret.xoff = fixed.I(e.maxWidth) - caret.x
+	e.caret.xoff = fixed.I(e.params.MaxWidth) - caret.x
 	e.updateSelection(selAct)
 	e.clampCursorToGraphemes()
 }