| layout | post |
|---|---|
| title | Interaction in Flutter Linear Gauge widget | Syncfusion |
| description | Learn here all about the interactions in Syncfusion Flutter Linear Gauge (SfLinearGauge) widget and more |
| platform | Flutter |
| control | SfLinearGauge |
| documentation | ug |
The shape and widget marker pointers in a Linear Gauge can be moved from one value to another using swipe or drag gestures.
The onChanged callback enables you to change the value of marker pointers at runtime through user interaction.
The following code sample demonstrates how to update a simple marker pointer value based on swipe or drag gestures:
{% highlight dart %}
double shapePointerValue = 25;
@override Widget build(BuildContext context) { return MaterialApp( home: Scaffold( body: Center( child: SfLinearGauge( markerPointers: [ LinearShapePointer( value: shapePointerValue, //Changes the value of shape pointer based on interaction onChanged: (value) { setState(() { shapePointerValue = value; }); }, color: Colors.blue[800], ), ], ), ), ), ); }
{% endhighlight %}
The following code sample demonstrates how to update multiple marker pointer values based on swipe or drag gestures:
{% highlight dart %}
double shapePointerValue = 85; double barPointerValue = 85; double widgetPointerValue = 26;
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
SfLinearGauge(
barPointers: [LinearBarPointer(value: shapePointerValue)],
markerPointers: [
LinearShapePointer(
value: shapePointerValue,
onChanged: (value) {
setState(() {
shapePointerValue = value;
});
},
color: Colors.blue[800]
),
],
),
SizedBox(height: 30),
SfLinearGauge(
barPointers: [LinearBarPointer(value: barPointerValue)],
markerPointers: [
LinearWidgetPointer(
position: LinearElementPosition.outside,
value: barPointerValue,
onChanged: (value) {
setState(() {
barPointerValue = value;
});
},
child: Container(
height: 20,
width: 20,
decoration: BoxDecoration(
color: Colors.orange[500],
shape: BoxShape.circle
)
),
),
],
),
SizedBox(height: 25),
SfLinearGauge(
axisTrackStyle: LinearAxisTrackStyle(
thickness: 10
),
markerPointers: [
LinearShapePointer(
value: widgetPointerValue,
shapeType: LinearShapePointerType.invertedTriangle,
position: LinearElementPosition.cross,
onChanged: (value) {
setState(() {
widgetPointerValue = value;
});
},
color: widgetPointerValue < 40
? Colors.green
: widgetPointerValue < 80
? Colors.orange
: Colors.red
),
LinearWidgetPointer(
value: widgetPointerValue,
onChanged: (value) {
setState(() {
widgetPointerValue = value;
});
},
child: Container(
width: 55,
height: 45,
child: Center(
child: Text(
widgetPointerValue.toStringAsFixed(0),
style: TextStyle(
fontWeight: FontWeight.w500,
fontSize: 20,
color: widgetPointerValue < 40
? Colors.green
: widgetPointerValue < 80
? Colors.orange
: Colors.red
),
),
),
),
position: LinearElementPosition.outside,
),
],
ranges: [
LinearGaugeRange(
endValue: widgetPointerValue,
color: widgetPointerValue < 40
? Colors.green
: widgetPointerValue < 80
? Colors.orange
: Colors.red,
position: LinearElementPosition.cross
)
],
),
],
)
),
)
);
}
{% endhighlight %}
