feat: initial circle arrow svg

routes/room_page_templates_preview.go

@@ -62,6 +62,72 @@ func (r *roomTableData)Tangens() float64 {
 	return math.Tan(math.Pi / float64(r.Total())) // Math.tan(Math.PI/m);
 }
 
+type arrowData struct {
+	Height, Width int
+	Radius int
+	StartX, StartY int
+	EndX, EndY int
+	LargeArcFlag int
+	Angle1X, Angle1Y int
+	Angle2X, Angle2Y int
+}
+
+func (r *roomTableData)ArrowData() arrowData {
+	// TODO take total and indexes from room data
+	// also figure out size to be around the people
+	// and this is somewhat a win
+	height, width := 150.0, 150.0
+	centerX, centerY := height/2, width/2
+	total := 5 // 0 to 4
+	startSector := 1
+	endSector := 5
+	if endSector < startSector {
+		endSector += total
+	}
+	radius := 50.0
+	startAngle := 90 + float64(startSector) * ( 360.0 / float64(total) )
+	endAngle := 90 + float64(endSector) * ( 360.0 / float64(total) ) 
+	startAngleRad := startAngle * (math.Pi / float64(180))
+	endAngleRad := endAngle * (math.Pi / float64(180))
+	// endAngle is radius angle, so perpendicular gives direction of teh arrow
+
+	x1 := centerX + radius * math.Cos(startAngleRad)
+	y1 := centerY + radius * math.Sin(startAngleRad)
+	x2 := centerX + radius * math.Cos(endAngleRad)
+	y2 := centerY + radius * math.Sin(endAngleRad)
+
+	arrowAngleOffset := math.Pi / 4 // 45 degrees
+	arrowPointDirection := endAngleRad - math.Pi / 2
+	arrowheadLen := 10.0
+	line1Angle := arrowPointDirection - arrowAngleOffset
+	line2Angle := arrowPointDirection + arrowAngleOffset
+	line1EndX := x2 + arrowheadLen * math.Cos(line1Angle)
+	line1EndY := y2 + arrowheadLen * math.Sin(line1Angle)
+	line2EndX := x2 + arrowheadLen * math.Cos(line2Angle)
+	line2EndY := y2 + arrowheadLen * math.Sin(line2Angle)
+
+	// indicates that the shorter of the two possible arcs should be used.
+	largeArcFlag := 0
+	if math.Abs(float64(endSector) - float64(startSector)) > float64(total)/2.0 {
+		// specifies that the longer arc should be chosen.
+		largeArcFlag = 1
+	}
+	return arrowData{
+		Height: int(height),
+		Width: int(width),
+		Radius: int(radius),
+		StartX: int(x1),
+		StartY: int(y1),
+		EndX: int(x2),
+		EndY: int(y2),
+		LargeArcFlag: largeArcFlag,
+		Angle1X: int(line1EndX),
+		Angle1Y: int(line1EndY),
+		Angle2X: int(line2EndX),
+		Angle2Y: int(line2EndY),
+	}
+}
+
 func personDataFromRoom(room *roomTableData, pId rooms.PersonId) personData {
 	person, exists := room.AllKnownPeople[pId]
 	if !exists || !slices.Contains(room.Paricipants, pId) {