Flutter reverse a text in a canvas - flutter

Question

I want to make a data wheel.
This is what it looks like :
My problem:
I want all the text that is between 181 degrees and 360 degrees, i.e. the left part of the circle, to be flipped 180 degrees so that the reading direction is easier.
My code:
class CanvasPainter extends CustomPainter
{
List<AreaEntity> areas;
CanvasPainter(this.areas)
: dotsPerRing = areas.length;
final int dotsPerRing;
final double dotRadius = 6;
#override
void paint(Canvas canvas, Size size) {
// General variable
final Offset ringCenter = size.center(Offset.zero);
final double centerCircleRadius = size.width / 6;
final double deltaAngle = 2 * pi / dotsPerRing;
// Main Circle
_drawBigCircle(
canvas: canvas,
offset: ringCenter,
radius: centerCircleRadius,
);
_drawDots(
canvas: canvas,
offset: ringCenter,
radius: centerCircleRadius,
deltaAngle: deltaAngle
);
_drawTextDot(
canvas: canvas,
size: size,
offset: ringCenter,
radius: centerCircleRadius,
deltaAngle: deltaAngle,
areas: areas
);
}
void _drawCenterCircle({
required Canvas canvas,
required Offset offset,
required double radius
}){
Paint outCirclePaint = Paint()
..color = AppColors.kcolor_bleu
..strokeCap = StrokeCap.round
..style = PaintingStyle.stroke
..strokeWidth = 2;
canvas.drawCircle(offset, 20, outCirclePaint);
Paint inCirclePaint = Paint()
..color = AppColors.kcolor_bleu
..strokeCap = StrokeCap.round;
canvas.drawCircle(offset, 5, inCirclePaint);
}
void _drawBigCircle({
required Canvas canvas,
required Offset offset,
required double radius
}){
Paint defaultCirclePaint = Paint()
..color = AppColors.kBg_light
..strokeCap = StrokeCap.round
..style = PaintingStyle.stroke
..strokeWidth = 1;
canvas.drawCircle(offset, radius, defaultCirclePaint);
}
void _drawDots({
required Canvas canvas,
required Offset offset,
required double radius,
required double deltaAngle
}){
// Dot
final Paint dotBackground = Paint()
..color = AppColors.kBg_normal
..strokeCap = StrokeCap.round;
final Paint dotPaint = Paint()
..color = AppColors.kFont_grey
..strokeCap = StrokeCap.round
..style = PaintingStyle.stroke
..strokeWidth = 3;
// Draw a single ring
Path dotCirclePath = Path();
for(int i = 0; i < dotsPerRing; i++){
dotCirclePath.addOval(
Rect.fromCircle(
center: offset + _rotateVector(
Offset(0, radius),
deltaAngle * i
),
radius: dotRadius
)
);
}
canvas.drawPath(dotCirclePath, dotBackground);
canvas.drawPath(dotCirclePath, dotPaint);
}
void _drawTextDot({
required Canvas canvas,
required Size size,
required Offset offset,
required double radius,
required double deltaAngle,
required List<AreaEntity> areas
}){
areas.forEach((m) {
double w3 = deltaAngle * m.id;
drawTextSlant(canvas, offset, radius, w3, m.text, TextStyle(
color: Colors.white,
fontSize: 8.0,
fontWeight: FontWeight.bold,
));
});
}
void drawTextSlant(
Canvas canvas,
Offset arcCenter,
double radius,
double w,
String text,
TextStyle style
){
final pos = Offset(radius, 0);
canvas.save();
canvas.translate(arcCenter.dx, arcCenter.dy);
canvas.rotate(w - degreeToRadian(90));
if(radianToDegree(w) > 180){
// => how to reverse text ??? -------------------------------------------------
}
final tp = measureText(canvas, text, style);
final ww = tp.height;
tp.paint(canvas, pos + Offset(15 , -ww / 2.0));
canvas.restore();
}
TextPainter measureText(Canvas canvas, String text, TextStyle style)
{
final textSpan = TextSpan(text: text, style: style);
final textPainter = TextPainter(text: textSpan, textDirection: TextDirection.ltr);
textPainter.layout(minWidth: 0, maxWidth: double.maxFinite);
return textPainter;
}
Offset _rotateVector(Offset vector, double angleInRadians)
{
return Offset(
(cos(angleInRadians) * vector.dx) - (sin(angleInRadians) * vector.dy),
(sin(angleInRadians) * vector.dx) - (cos(angleInRadians) * vector.dy)
);
}
double degreeToRadian(double degree) {
return degree * pi / 180;
}
double radianToDegree(double radian) {
return radian * 180 / pi;
}
#override
bool shouldRepaint(CustomPainter oldDelegate) {
return true;
}
}
I'm new to canvas so if you have any suggestions to improve my code I'll gladly accept the advice
Any guidance on the best way to accomplish this would be appreciated.
EDIT : I succeeded I edit the code
void _drawTextDot({
required Canvas canvas,
required Size size,
required Offset offset,
required double radius,
required double deltaAngle,
required List<PaxsAreaEntity> areas
}){
areas.forEach((m) {
double w3 = deltaAngle * m.id;
drawTextSlant(canvas, offset, radius, w3, m.text, TextStyle(
color: AppColors.kFont_grey,
fontSize: 6.0,
fontWeight: FontWeight.bold,
), size);
});
}
void drawTextSlant(
Canvas canvas,
Offset arcCenter,
double radius,
double w,
String text,
TextStyle style,
Size size
){
double distanceFromDot = 20;
final pos = Offset(0, 0);
canvas.save();
canvas.translate(size.width / 2, size.height / 2);
canvas.rotate(degreeToRadian(-90));
canvas.translate(radius * cos(w), radius * sin(w));
canvas.rotate(w);
final tp = measureText(canvas, text, style);
final ww = tp.height;
if(radianToDegree(w) > 180){
canvas.rotate(degreeToRadian(180));
canvas.translate(-tp.width, 0);
distanceFromDot = distanceFromDot * -1;
}
tp.paint(canvas, pos + Offset(distanceFromDot , -ww / 2.0));
canvas.restore();
}