frefresh

help you to build pull-down refresh and pull-up loading in the simplest way.

although unprecedented simplicity, but the effect is amazing. it also supports configuration refresh and loading elements. the complete controller allows you to help you control the entire dynamic process.

guide

⚙️ parameter & interface

�� frefresh param

param	type	necessary	default	desc
child	widget	true	null	main view content
header	widget	false	null	elements that will be displayed when you pull down and refresh
headerbuilder	headerbuilder	false	null	construct a pull-down refresh element. [header] configuration will be overwritten.
headerheight	double	false	50.0	[header] the height of the area
headertrigger	double	false	0.0	the distance to trigger pull-down refresh should be greater than [headerheight]
onrefresh	voidcallback	false	null	callback when refresh is triggered
footer	widget	false	null	elements that will be displayed when pulling up
footerbuilder	footerbuilder	false	null	build pull-up loading elements. will override [footer] configuration.
footerheight	double	false	0.0	[footer] the height of the area
footertrigger	double	false	0.0	the distance to trigger the pull-up loading should be greater than [headerheight]
shouldload	bool	false	true	whether the pull-up load should be triggered. in some scenarios, when the loading is completed, the pull-up loading element will need to be turned into a footer
onload	voidcallback	false	null	callback when loading is triggered
controller	frefreshcontroller	false	null	[refresh] controller. see [refresh controller] for details

⌨️ frefreshcontroller

�� param

param	type	desc
refreshstate	refreshstate	get the pull-down refresh status. see [refreshstate] for details
loadstate	loadstate	get the pull-up loading status. see [loadstate] for details
position	double	current scroll position
scrollmetrics	scrollmetrics	current scroll information. see [scrollmetrics] for details.
backoriginonloadfinish	bool	when loading is completed, whether to return to the original position. this parameter is useful when the gridview only adds one element.

�� interface

---

• void refresh({duration duration = const duration(milliseconds: 300)})

actively trigger pull-down refresh.

[duration] the duration of the pull-down effect. default 300ms

---

• finishrefresh()

end pull-down refresh.

---

• finishload()

end pull-up loading.

---

• void setonstatechangedcallback(onstatechangedcallback callback)

set up status listener. e.g .:

controller.setonstatechangedcallback((state){
  if (state is refreshstate) {

  }
  if (state is loadstate) {

   }
})

---

• void setonscrolllistener(onscrolllistener onscrolllistener)

set up scroll listener. receive [scrollmetrics].

---

• void scrollto(double position, {duration duration = const duration(milliseconds: 300)})

scroll to the specified position.

---

• void scrollby(double offset, {duration duration = const duration(milliseconds: 300)})

scroll the specified distance.

---

• void jumpto(double position)

jump to the specified position.

�� refreshstate

value	desc
preparing_refresh	reach [headertrigger], ready to enter refresh state
refreshing	refreshing
finishing	refresh ending
idle	idle state

�� loadstate

value	desc
preparing_load	reach [footertrigger], ready to enter the loading state
loading	loading
finishing	load ending
idle	idle state

�� demo

�� refresh example

this is our most common pull-down refresh example in daily development ��. believe me, if you want to build such an effect, it will be very difficult!

but if you use frefresh, the situation is completely different.

next, we only need a few lines of code to complete the construction of this effect.

1. create frefreshcontroller

/// create a controller
frefreshcontroller controller = frefreshcontroller()

2. create frefresh

frefresh(

  /// set up the controller
  controller: controller,

  /// create header
  header: buildrefreshview(),

  /// need to pass the size of the header area
  headerheight: 75.0,

  /// content area widget
  child: listview.builder(
      physics: neverscrollablescrollphysics(),
      shrinkwrap: true,
      ...
  ),

  /// this function will be called back after entering refreshing
  onrefresh: () {

     /// end refresh via controller
     controller.finishrefresh();
  },
);

done ��！

this is all you need to do to create a pull-down refresh.

frefresh takes care of everything, developers only need to focus on the construction of the header area and content area.

⚠️ attention，to use listview, gridview in frefresh, you need to configure their physics: neverscrollablescrollphysics (), shrinkwrap: true, otherwise it will affect the scrolling and layout effects.

�� headerbuilder demo

frefresh(
  controller: controller,

  /// build the header area with headerbuilder
  headerbuilder: (setter, constraints) {
    return fsuper(

       /// get the available space in the current header area
       width: constraints.maxwidth,
       height: constraints.maxheight,
       ...
       onclick:{
          setter((){
             /// refresh the header area
          })
       },
    );
  },
  headerheight: 100.0,

  /// build content area
  child: gridview.builder(),

  /// this function will be called back after entering the refreshing state
  onrefresh: () {

    /// finish refresh
    controller.finishrefresh();
  }
)

frefresh provides a very flexible header area construction method, which is to complete the construction through the headerbuilder function.

in the headerbuilder function, the developer can get the refresh function statesetter for the partial refresh header area and the real-time size of the header area through the parameters.

this way, the header area is given more open creativity.

�� load example

corresponding to the pull-down refresh, the construction of the pull-up loading effect is also very simple.

1. create frefreshcontroller

/// create a controller
frefreshcontroller controller = frefreshcontroller()

2. create frefresh

frefresh(

  /// setup the controller
  controller: controller,

  /// create footer area
  footer: linearprogressindicator(),

  /// need to setup footer area height
  footerheight: 20.0,

  /// create content area
  child: buildercontent(),

  /// this function will be called back after entering the loading state
  onload: () {
    
    /// end loading state
    controller.finishload();
  },
)

building pull-ups is equally simple enough. developers only need to pay attention to the construction of footer area and content area, and the state changes and visual effects control during the pull-up loading process can be safely handed over to frefresh.

�� footerbuilder demo

frefresh(
  controller: controller,

  /// build footer area widget by footerbuilder
  footerbuilder: (setter) {

    /// get refresh status, partially update the content of footer area
    controller.setonstatechangedcallback((state) {
      setter(() {
        ...
      });
    });
    return buildfooter();
  },
  footerheight: 38.0,
  child: buildcontent(),
  onload: () {
    controller.finishload();
  },
)

frefresh also provides a builder function footerbuilder for building the footer area. through this function, you can get the refresh function statesetter which refreshes only the footer area.

in this way, the developer can easily change the view of the footer area according to the status or some other conditions. very intimate ��.

⚙️ frefreshcontroller

frefresh provides developers with intimate controllers frefreshcontroller, which supports many convenient capabilities.

1. add controller to frefresh

/// create controller
frefreshcontroller controller = frefreshcontroller()

/// configure controller for frefresh
frefresh(
  controller: controller,
)

when the developer creates a controller and then sets it into a frefresh, the controller can start to monitor the status of this frefresh and control it.

2. stop refreshing or loading

when the refresh state or loading state is triggered, data processing tasks such as network requests are usually performed. after these tasks are completed, we need to stop the refresh state or loading state. how to do it?

• controller.finishrefresh() can stop refreshing
• controller.finishload() can stop loading

3. state change listen

controller5.setonstatechangedcallback((state) {
  /// refresh status
  if (state is refreshstate) {
  }
  /// loading state
  if (state is loadstate) {
  }
});

through the above simple code, you can monitor the status change of frefresh, whether it is pull-down refresh or pull-up loading.

4. scroll listen

controller.setonscrolllistener((metrics) {
  /// get scroll information
});

frefreshcontroller it is really convenient to add sliding monitor. the parameters received is [scrollmetrics]，it can get very comprehensive information such as current scroll distance, maximum scroll distance, whether it exceeds the scroll range, etc..

5. actively trigger refresh

through frefreshcontroller, developers can also actively trigger a refresh, and can specify the length of time to slide to the refresh position.

controller.refresh(duration: duration(milliseconds: 2000));

this feature is very useful in many scenarios.

6. scroll control

frefreshcontroller provides a variety of intimate and delicate sliding controls for developers to choose.

/// scroll to the specified position
controller.scrollto(100.0, duration:duration(milliseconds: 2000));

/// scroll the specified distance
controller.scrollby(20.0, duration:duration(milliseconds: 800));

/// jump to the specified position
controller.jumpto(100.0);

this makes many beautiful interactions easier to build.

�� how to use？

add dependencies in the project pubspec.yaml file:

pub dependency

dependencies:
  frefresh: ^<version number>

git dependency

dependencies:
  frefresh:
    git:
      url: '[email protected]:fliggy-mobile/frefresh.git'
      ref: '<branch number or tag number>'

how to run demo project?

1. clone project to local
2. enter the project example directory and run the following command

flutter create .

3. run the demo in example