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Description:

sleek circular slider

Sleek circular slider/progress bar & spinner for Flutter #

A highly customizable circular slider/progress bar & spinner for Flutter.

Getting Started #

Installation
Basic Usage
SleekCircularSlider parameters
CircularSliderAppearance parameters
CustomSliderWidths parameters
CustomSliderColors parameters
InfoProperties parameters
YouTube video

Installation #
Add

sleek_circular_slider : ^lastest_version

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to your pubspec.yaml, and run
flutter packages get
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in your project's root directory.
Basic Usage #
Import it to your project file
import 'package:sleek_circular_slider/sleek_circular_slider.dart';
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And add it in its most basic form like it:
final slider = SleekCircularSlider(
appearance: CircularSliderAppearance(),
onChange: (double value) {
print(value);
});
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There are additional optional parameters one can initialize the slider with.
final slider = SleekCircularSlider(
min: 0,
max: 1000,
initialValue: 426,
onChange: (double value) {
// callback providing a value while its being changed (with a pan gesture)
},
onChangeStart: (double startValue) {
// callback providing a starting value (when a pan gesture starts)
},
onChangeEnd: (double endValue) {
// ucallback providing an ending value (when a pan gesture ends)
},
innerWidget: (double value) {
// use your custom widget inside the slider (gets a slider value from the callback)
},
);
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Use as a progress bar #
Slider user's interaction will be disabled if there is either no [onChange] or [onChangeEnd] provided. That way one can use the widget not as a slider but as a progress bar.
final slider = SleekCircularSlider(
appearance: CircularSliderAppearance(
customWidths: CustomSliderWidths(progressBarWidth: 10)),
min: 10,
max: 28,
initialValue: 14,
);
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Use as a spinner #
There is one more use case for the library. It's a spinner which can be shown to users while loading etc. In this mode the widget is not interactive and ignores all angles so there is no need to provide them.
final slider = SleekCircularSlider(
appearance: CircularSliderAppearance(
spinnerMode: true,
));
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SleekCircularSlider parameters #

Parameter
Default
Description

appearance CircularSliderAppearance

A set of objects describing the slider look and feel.

min double
0
The minimum value the user can select. Must be less than or equal to max.

max double
100
The maximum value the user can select. Must be greater than or equal to min.

initialValue double
50
The initial value for this slider.

onChange OnChange(double value)

Called during a drag when the user is selecting a new value for the slider by dragging.

onChangeStart OnChange(double value)

Called when the user starts selecting a new value for the slider.

onChangeEnd OnChange(double value)

Called when the user is done selecting a new value for the slider.

innerWidget Widget InnerWidget(double value)

A custom widget to replace the build in text labels which can capture a slider value from the callback.

CircularSliderAppearance parameters #

Parameter
Default
Description

size double
150
The width & height value for the slider.

startAngle double
150
The angle (in degrees) the slider begins with.

angleRange double
240
The angle range (in degrees) the slider reaches when maximum value set.

counterClockwise bool
false
The setting indicating direction of the widget.

customWidths CustomSliderWidths

The object with a set of widths for the track, bar, shadow etc.

customColors CustomSliderColors

The object with a set of colors for the track, bar, shadow etc.

infoProperties InfoProperties

The object with a set of properties for internal labels displaying a current slider value.

animationEnabled bool
true
The setting indicating whether external changes of a slider value should be animated.

spinnerMode bool
false
The setting turning the widget into a spinner.

spinnerDuration int
1500
The spinner animation duration in miliseconds

animDurationMultiplier double
1.0
The multiplier of duration for the animation when value changed

CustomSliderWidths parameters #

Parameter
Default
Description

trackWidth double
progressBarWidth / 4
The width of the slider's track.

progressBarWidth double
slider's size / 10
The width of the slider's progress bar.

shadowWidth double
progressBarWidth * 1.4
The width of the slider's shadow.

handlerSize double
progressBarWidth / 5
The size of the slider's handler.

CustomSliderColors parameters #

Parameter
Default
Description

trackColor Color
#DCBEFB
The color of the slider's track.

trackColors List
null
The list of colors for the track's gradient.

trackGradientStartAngle double
0
The start angle for the track's gradient.

trackGradientEndAngle double
180
The end angle for the track's gradient.

progressBarColor Color

The color of the slider's progress bar. Won't be used if the slider uses gradient progressBarColors != null

progressBarColors List
[#1E003B, #EC008A, #6285DA]
The list of colors for the progress bar's gradient.

gradientStartAngle double
0
The start angle for the progress bar's gradient.

gradientEndAngle double
180
The end angle for the progress bar's gradient.

dynamicGradient bool
false
The gradient angles will change dynamically with value changing. If true it will ignore both the grandientStartAngle and gradientEndAngle

dotColor Color
#FFFFFF
The color of the slider's handle.

hideShadow bool
false
The setting indicating whether the shadow should be showed.

shadowColor Color
#2C57C0
The color of the shadow.

shadowMaxOpacity double
0.2
The opacity of the shadow in its darker part.

shadowStep double

The shadow is being painted with a number of steps. This value determines how big is a width of each step. The more steps are painted the softer the shadow is. For a flat shadow use a difference between the shadowWidth and the progressWidth for the shadowStep.

InfoProperties parameters #

Parameter
Default
Description

mainLabelStyle TextStyle

The text style of the main text widget displaying a slider's current value.

topLabelStyle TextStyle

The text style of the top text widget.

bottomLabelStyle TextStyle

The text style of the bottom text widget.

topLabelText String

The text for the top text widget.

bottomLabelText String

The text for the bottom text widget.

modifier String PercentageModifier(double percentage)
closure adding the % character
The closure allowing to modify how a current value of the slider is displayed.

Example of the modifier
String percentageModifier(double value) {
final roundedValue = value.ceil().toInt().toString();
return '$roundedValue %';
}
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It will convert a current value to int and add the % sufix to it.
YouTube video #

Todo #

add divisions

add more comments to document the code

add the counterclockwise direction

add the spinner mode

add the second handle (interval selection)

add text labels on a curved path

Acknowledgments #

Hat tip to David Anaya for his awesome blog post about building a circular slider in Flutter and radian to degrees conversions which helped me a lot!