Allow left, center, and right alignment of text

display/slot.go

@@ -9,6 +9,14 @@ import (
 	rgbmatrix "git.dvdt.dev/david/bitcoin-ticker-pi/go-rpi-rgb-led-matrix"
 )
 
+type Alignment uint8
+
+const (
+	Left Alignment = iota
+	Center
+	Right
+)
+
 var (
 	ErrUnsupportedSlotHeight = errors.New("unsupported slot height")
 )
@@ -33,15 +41,17 @@ func drawRow(canvas *rgbmatrix.Canvas, row []color.RGBA, x, y int) {
 }
 
 type Slot struct {
+	alignment     Alignment
 	segmentLimit  int
 	segmentHeight int
 	segmentWidth  int
-	x, y          int
+	x, xoffset, y int
 	text          []Segment
 }
 
-func NewSlot(limit, height, width, x, y int) *Slot {
+func NewSlot(alignment Alignment, limit, height, width, x, y int) *Slot {
 	return &Slot{
+		alignment:     alignment,
 		segmentLimit:  limit,
 		segmentHeight: height,
 		segmentWidth:  width,
@@ -61,6 +71,20 @@ func (s *Slot) Update(text []Segment) error {
 		}...)
 	}
 
+	// Default to left alignment.
+	s.xoffset = 0
+	if s.alignment == Center {
+		s.xoffset = ((s.segmentLimit * s.segmentWidth) - (len(text) * s.segmentWidth)) / 2
+	}
+	if s.alignment == Right {
+		s.xoffset = (s.segmentLimit * s.segmentWidth) - (len(text) * s.segmentWidth)
+	}
+
+	fmt.Printf("segmentLimit: %d\n", s.segmentLimit)
+	fmt.Printf("segmentWidth: %d\n", s.segmentWidth)
+	fmt.Printf("len(text): %d\n", len(text))
+	fmt.Printf("xoffset value: %d\n", s.xoffset)
+
 	var font fonts.Font
 	switch s.segmentHeight {
 	case 5:
@@ -88,6 +112,6 @@ func (s *Slot) Update(text []Segment) error {
 
 func (s *Slot) Draw(canvas *rgbmatrix.Canvas) {
 	for i, segment := range s.text {
-		segment.Draw(canvas, s.x+(i*s.segmentWidth), s.y)
+		segment.Draw(canvas, s.x+(i*s.segmentWidth)+s.xoffset, s.y)
 	}
 }