Issue
For some reason, my CustomPainter does not draw anything to the screen. I'm trying to build a Pie-Chart but the painter only works when I set the sweepAngle to 2*pi.
The Widget where CustomPaint is called has the following structure:
class PieChart extends StatelessWidget {
const PieChart({
Key? key,
}) : super(key: key);
@override
Widget build(BuildContext context) {
return SizedBox(
height: 160,
width: 210,
child: CustomPaint(
painter: PieChartPainter(categories: dataset, width: 10),
),
);
}
}
This is my CustomPainter class:
class PieChartPainter extends CustomPainter {
PieChartPainter({
required this.categories,
required this.width,
});
final List<Category> categories;
final double width;
@override
void paint(Canvas canvas, Size size) {
Offset center = Offset(size.width / 2, size.height / 2);
double radius = min(size.width / 2, size.height / 2);
double total = 0;
// Calculate total amount from each category
for (var expense in categories) {
total += expense.amount;
}
// The angle/radian at 12 o'clock
double startRadian = -pi / 2;
for (var index = 0; index < categories.length; index++) {
final currentCategory = categories.elementAt(index);
final sweepRadian = currentCategory.amount / total * 2 * pi;
final paint = Paint()
..style = PaintingStyle.fill
..strokeWidth = width
..color = categoryColors.elementAt(index % categories.length);
final rect = Rect.fromCenter(
center: center, width: radius * 2, height: radius * 2);
canvas.drawArc(
rect,
startRadian,
2 * pi, // should really be "sweepRadian"
false,
paint,
);
startRadian += sweepRadian;
}
}
@override
bool shouldRepaint(PieChartPainter oldDelegate) {
return true;
}
}
I can almost certainly say that the problem has nothing to do with the data and colors that I provide, because whenever I log the current elements to the console, it gives the correct output. Here, you can see my Widget structure:
And here is an image of the component itself: (Notice that only the last category-color is shown for the entire circle, because whenever I use a sweepAngle that is less than 2*pi, the entire widget doesn't show colors.)
This is the component when I set a sweepAngle that is less than 2*pi:
I really cannot figure out what might be causing this issue. Does anyone have an Idea what else is influenced by the sweepAngle parameter? I also have no idea why the colored circles to the left of the individual categories are not visible, because they're rendered in an entirely different Widget-branch... If you have any idea on how to solve this, I would be more than happy to provide more information but as long as I don't know where to look, I don't want to spam this issue with unnecessary information.
Solution
For anyone wondering:
The problem had to do with the "--enable-software-rendering" argument. Once I ran flutter with flutter run --enable-software-rendering
, it all worked as expected.
Answered By - NKQDR Answer Checked By - Willingham (PHPFixing Volunteer)
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