I am using canvas to draw circles in flutter, is there any easy way to draw circles filled with lines?
PS:I know I can calculate each line's points then drawing lines in circle. But is there any simple method that can be implemented without calculation?
This is what I want to achieve:
Finally, I found an easy and ingenious solution without calculation.
That is creating a linear gradient filled in the circle.
give two colors for the start and end of the gradient.
give transparent to the start color.
give the actual line color to the end color.
Paint paint = new Paint();
paint.color =Colors.red;
paint.style = PaintingStyle.fill;
paint.shader = ui.Gradient.linear(
start,
//the line interval is 20
Offset(start.dx + 20, start.dy),
[
//give transparent to start color, give actual line color to the end color
Colors. transparent,
Colors.red
],
//The interval [0.0,0.9] is transparent, and the interval [0.9,1.0] is red. So it looks like drawing red lines
[0.90, 1.0],
//just repeat the gradient
TileMode.repeated,
null);
canvas.drawCircle(
Offset(centerX, centerY),
radius,
paint);
Related
I'm trying to fill a curved rectangle, but it is overflowing from the curved part, have used paths to create this shape. Any suggestions for how to achieve this.
Or is there any way to create a rectangle with 4 offset values, whose one side is curved like this?
I have offset values of two straight line (x1,y1), (x2,y2), (x3,y3) and (x4,y4). Any references?
final path = Path();
path.moveTo(87.75, 10.06);
path.lineTo(263.25, 80.06);
path.lineTo(263.25, 359.0);
path.lineTo(87.75, 359.0);
canvasWrapper.drawPath(path, _barAreaPaint..color = Colors.red);
Try drawing an arc
Rect rect = Rect.fromLTWH(0.0, 0.0, size.width, size.height);
path.arcTo(
rect,
0.0,
pi / 2,//adjust radians accordingly
false);
}
I'm recreating the graphical macOS time picker for macos_ui and I'm having some difficulty painting the inner shadow gradient correctly. This shadow, along with the gradient of the clock's border, help give the clock a sort of 3D look.
Here is a screenshot of the native time picker:
As you can see, there is a shadow effect for the inner top half of the clock. It starts out white right around hour 9, then gets gradually darker and thicker as it reaches hour 12, and reverses back down to white at hour 3.
I've so far achieved the following:
As you can see, this is not correct. Here is the code I'm using to achieve this incorrect effect:
void _paintInnerShadow(Canvas canvas, Size size) {
Paint innerShadowPainter = Paint()
..strokeWidth = 3.0
..isAntiAlias = true
..shader = const LinearGradient(
begin: Alignment.centerLeft,
end: Alignment.bottomLeft,
stops: [0.0, 0.5],
colors: [
MacosColor(0xFFA3A4A5),
MacosColors.white,
],
).createShader(
Rect.fromCircle(
center: size.center(Offset.zero),
radius: clockHeight / 2,
),
)
..style = PaintingStyle.stroke;
canvas.drawCircle(
size.center(Offset.zero),
size.shortestSide / 2.0,
innerShadowPainter,
);
}
What is the correct gradient I need to use to match the native look? I've experimented with Linear, Radial, and Sweep gradients and while I think LinearGradient is the right one, I haven't been able to work out the correct parameters for it.
Is there a way to choose a color to be replaced for transparent when painting an image to the Flutter canvas? I have a spritesheet with magenta background and I want it to be transparent when painted. I am painting in the following way:
void _draw(Canvas canvas, Offset offset, ui.Image image) {
final paint = Paint();
canvas.drawImage(image, offset, paint);
}
You just need to set an ARGB color with the alpha value
paint.color = Color.fromARGB(alpha, r, g, b)
Where alpha is a double between 0 and 1, 0 being transparent and 1 the most visible. R,G,B is the level of red blue green colors applied.
The white color is:
r=255, g=255, b=255
The black color is:
r=0, g=0, b=0
So in your case:
paint.color = Color.fromARGB(0, 0, 0, 0)
How to draw a filled polygon in flutter?
Currently I am able to a eyebrow shape with array of point like below.
Path leftEyePath = Path();
leftEyePath.moveTo(leftEye[0].getX(),leftEye[0].getY());//starting point
for(int i=1;i<leftEye.length;i++){
leftEyePath.lineTo(leftEye[i].getX(),leftEye[i].getY());
}
canvas.drawPath(leftEyePath,painter);
The code above will eventually draw a connected polygon with many line , but how do I draw a filled polygon with color I want?
EDIT:
I am currently go through their function and found drawShadow(..)
canvas.drawShadow(leftEyePath, Colors.orange[600],0,true);
Unfortunately it only draw transparent color.
Below is my current output.
You may change your paint style into PaintingStyle.fill. The paint brush will automatically fill up the closing area of your path.
Paint _filledPainter = new Paint()
..style = PaintingStyle.fill
;
When I draw lines on a CustomPainter's canvas using code like this:
var paint = Paint()
..style = PaintingStyle.stroke
..strokeWidth = 4.0
..color = Colors.grey;
canvas.drawLine(fromOffsetA, toOffsetB, paint);
canvas.drawLine(fromOffsetC, toOffsetD, paint);
If the two lines partly overlap over one another, then the section of the lines that overlap show the line color as being darker than in the sections of the line that do not overlap.
I am guessing that this is by design so, my question is, how do I draw lines that overlap one another and at the same time prevent the lines' color from darkening in the overlapped sections?
I am thinking I need to set the paint's Blendmode to a specific value or something along those lines?