New helper to handle custom layouts

layouts.go

@@ -0,0 +1,101 @@
+package main
+
+import (
+	"fmt"
+	"image"
+	"strconv"
+	"strings"
+)
+
+// Layout contains the data to represent the layout of the widget.
+type Layout struct {
+	frames []image.Rectangle
+	size   int
+	margin int
+	height int
+}
+
+// NewLayout returns a new Layout with the accoriding size.
+func NewLayout(size int) *Layout {
+	margin := size / 18
+	height := size - (margin * 2)
+
+	return &Layout{
+		size:   size,
+		margin: margin,
+		height: height,
+	}
+}
+
+// DefaultLayout returns a layout that is evenly split in frameCount horziontal containers.
+func (l *Layout) DefaultLayout(frameCount int) []image.Rectangle {
+	if frameCount < 1 {
+		frameCount = 1
+	}
+	for i := 0; i < frameCount; i++ {
+		frame := l.defaultFrame(frameCount, i)
+		l.frames = append(l.frames, frame)
+	}
+	return l.frames
+}
+
+// FormatLayout returns a layout that is formatted according to frameReps.
+func (l *Layout) FormatLayout(frameReps []string, frameCount int) []image.Rectangle {
+	if frameCount < 1 {
+		frameCount = 1
+	}
+	for i := 0; i < frameCount; i++ {
+		if len(frameReps) < i+1 {
+			frame := l.defaultFrame(frameCount, i)
+			l.frames = append(l.frames, frame)
+			continue
+		}
+
+		frame, err := formatFrame(frameReps[i])
+		if err != nil {
+			fmt.Println("using default frame: ", err)
+			frame = l.defaultFrame(frameCount, i)
+		}
+		l.frames = append(l.frames, frame)
+	}
+	return l.frames
+}
+
+// Returns the Rectangle representing the index-th horizontal cell.
+func (l *Layout) defaultFrame(cells int, index int) image.Rectangle {
+	lower := l.margin + (l.height/cells)*index
+	upper := l.margin + (l.height/cells)*(index+1)
+	return image.Rect(0, lower, l.size, upper)
+}
+
+// Converts the string representation of a rectangle into a image.Rectangle.
+func formatFrame(layout string) (image.Rectangle, error) {
+	split := strings.Split(layout, "+")
+	if len(split) < 2 {
+		return image.Rectangle{}, fmt.Errorf("invalid rectangle format")
+	}
+	position, errP := formatCoord(split[0])
+	if errP != nil {
+		return image.Rectangle{}, errP
+	}
+	extent, errE := formatCoord(split[1])
+	if errE != nil {
+		return image.Rectangle{}, errE
+	}
+
+	return image.Rectangle{position, position.Add(extent)}, nil
+}
+
+// Converts the string representation of a point into a image.Point.
+func formatCoord(coords string) (image.Point, error) {
+	split := strings.Split(coords, "x")
+	if len(split) < 2 {
+		return image.Point{}, fmt.Errorf("invalid point format")
+	}
+	posX, errX := strconv.Atoi(split[0])
+	posY, errY := strconv.Atoi(split[1])
+	if errX != nil || errY != nil {
+		return image.Point{}, fmt.Errorf("invalid point format")
+	}
+	return image.Pt(posX, posY), nil
+}