我想知道在Flutter中有没有一种创建渐变颜色滑块小部件的方法。这里是滑块类的链接,但是没有"SliderTheme"或类似的内容。
LinearGradient gradient = LinearGradient(
colors: <Color> [
Colors.red,
Colors.orange,
Colors.yellow,
Colors.green,
Colors.blue,
Colors.blue[900],
Colors.purple
]
);
SliderTheme(
data: SliderThemeData(
trackShape: GradientRectSliderTrackShape(gradient: gradient, darkenInactive: false),
),
child: Slider(
min: 0,
max: 10,
value: value,
onChanged: (double value) {},
)
),
形状类:
import 'package:flutter/material.dart';
/// Based on https://www.youtube.com/watch?v=Wl4F5V6BoJw
class GradientRectSliderTrackShape extends SliderTrackShape
with BaseSliderTrackShape {
const GradientRectSliderTrackShape({
this.gradient = const LinearGradient(
colors: [
Colors.red,
Colors.yellow,
],
),
this.darkenInactive = true,
});
final LinearGradient gradient;
final bool darkenInactive;
@override
void paint(
PaintingContext context,
Offset offset,
{
required RenderBox parentBox,
required SliderThemeData sliderTheme,
required Animation<double> enableAnimation,
required TextDirection textDirection,
required Offset thumbCenter,
bool isDiscrete = false,
bool isEnabled = false,
double additionalActiveTrackHeight = 2,
}
) {
assert(sliderTheme.disabledActiveTrackColor != null);
assert(sliderTheme.disabledInactiveTrackColor != null);
assert(sliderTheme.activeTrackColor != null);
assert(sliderTheme.inactiveTrackColor != null);
assert(sliderTheme.thumbShape != null);
assert(sliderTheme.trackHeight != null && sliderTheme.trackHeight! > 0);
final Rect trackRect = getPreferredRect(
parentBox: parentBox,
offset: offset,
sliderTheme: sliderTheme,
isEnabled: isEnabled,
isDiscrete: isDiscrete,
);
final activeGradientRect = Rect.fromLTRB(
trackRect.left,
(textDirection == TextDirection.ltr)
? trackRect.top - (additionalActiveTrackHeight / 2)
: trackRect.top,
thumbCenter.dx,
(textDirection == TextDirection.ltr)
? trackRect.bottom + (additionalActiveTrackHeight / 2)
: trackRect.bottom,
);
// Assign the track segment paints, which are leading: active and
// trailing: inactive.
final ColorTween activeTrackColorTween = ColorTween(
begin: sliderTheme.disabledActiveTrackColor,
end: sliderTheme.activeTrackColor);
final ColorTween inactiveTrackColorTween = darkenInactive
? ColorTween(
begin: sliderTheme.disabledInactiveTrackColor,
end: sliderTheme.inactiveTrackColor
)
: activeTrackColorTween;
final Paint activePaint = Paint()
..shader = gradient.createShader(activeGradientRect)
..color = activeTrackColorTween.evaluate(enableAnimation)!;
final Paint inactivePaint = Paint()
..color = inactiveTrackColorTween.evaluate(enableAnimation)!;
final Paint leftTrackPaint;
final Paint rightTrackPaint;
switch (textDirection) {
case TextDirection.ltr:
leftTrackPaint = activePaint;
rightTrackPaint = inactivePaint;
break;
case TextDirection.rtl:
leftTrackPaint = inactivePaint;
rightTrackPaint = activePaint;
break;
}
final Radius trackRadius = Radius.circular(trackRect.height / 2);
final Radius activeTrackRadius = Radius.circular(trackRect.height / 2 + 1);
context.canvas.drawRRect(
RRect.fromLTRBAndCorners(
trackRect.left,
(textDirection == TextDirection.ltr)
? trackRect.top - (additionalActiveTrackHeight / 2)
: trackRect.top,
thumbCenter.dx,
(textDirection == TextDirection.ltr)
? trackRect.bottom + (additionalActiveTrackHeight / 2)
: trackRect.bottom,
topLeft: (textDirection == TextDirection.ltr)
? activeTrackRadius
: trackRadius,
bottomLeft: (textDirection == TextDirection.ltr)
? activeTrackRadius
: trackRadius,
),
leftTrackPaint,
);
context.canvas.drawRRect(
RRect.fromLTRBAndCorners(
thumbCenter.dx,
(textDirection == TextDirection.rtl)
? trackRect.top - (additionalActiveTrackHeight / 2)
: trackRect.top,
trackRect.right,
(textDirection == TextDirection.rtl)
? trackRect.bottom + (additionalActiveTrackHeight / 2)
: trackRect.bottom,
topRight: (textDirection == TextDirection.rtl)
? activeTrackRadius
: trackRadius,
bottomRight: (textDirection == TextDirection.rtl)
? activeTrackRadius
: trackRadius,
),
rightTrackPaint,
);
}
}
(Github Gist)Widget get gradientContainer => Container(
width: double.infinity,
height: height,
decoration: BoxDecoration(
gradient: gradient
),
);
Widget get slider =>SliderTheme(
data: SliderThemeData(
trackShape: CustomTrackShape(),
activeTrackColor: Colors.transparent,
inactiveTrackColor: Colors.red,
thumbColor: Colors.white,
overlayColor: Colors.transparent
),
child: Slider(
value: value,
max: max,
min: min,
onChanged: (double newValue){
setState(() {
value=newValue;
});
}
)
同时,为了在滑块上添加轨道填充,我们的自定义轨道形状类也在这里;
);
(这句话没有上下文,无法进行准确翻译,请提供更多信息)class CustomTrackShape extends RoundedRectSliderTrackShape {
Rect getPreferredRect({
@required RenderBox parentBox,
Offset offset = Offset.zero,
@required SliderThemeData sliderTheme,
bool isEnabled = false,
bool isDiscrete = false,
}) {
final double trackHeight = sliderTheme.trackHeight;
final double trackLeft = offset.dx;
final double trackTop = offset.dy + (parentBox.size.height - trackHeight) / 2;
final double trackWidth = parentBox.size.width;
return Rect.fromLTWH(trackLeft, trackTop, trackWidth, trackHeight);
}
}
而且我们终于可以将它们合并;
Widget get gradientSlider=>Padding(
child: SizedBox(
child: Stack(
children: [
gradientContainer,
slider,
],
alignment: Alignment.center,
),
),
padding: padding
最后,您只需要填充填充、宽度、高度、渐变按钮容器高度属性即可。
使用这个库,它非常容易实现。
https://pub.dev/packages/flutter_xlider
FlutterSlider(
values: [40],
max: 100,
min: 0,
trackBar: FlutterSliderTrackBar(
activeTrackBar: BoxDecoration(
gradient: AppColors.sliderGradient,
borderRadius: BorderRadius.circular(5)
),
activeTrackBarHeight: 6,
),
onDragging: (handlerIndex, lowerValue, upperValue) {
},
);
**更新
看起来公开版本还没有升级到空安全。但是主分支已经有了。使用以下代码获取空安全版本。
flutter_xlider:
git:
url: https://github.com/Ali-Azmoud/flutter_xlider.git
ref: master
'but there's no "SliderTheme"'
是什么意思? - pskinkSearch API Docs
搜索字段。 - pskink*Shape
属性。 - pskink