jumping speed keeps increasing in flutter - flutter

Question

I was building a flutter project ( a small game) where my container(player) can jump when barriers came to it I was able to make a jump using the code below but every time pressed jump it keeps getting faster and faster I don't think the issue is with variables I can't figure out what is happening (there were no errors in the code)
the jump part of code is made bold to make it easy to find for you
import 'dart:async';
import 'package:Buckly/extensions/player.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:Buckly/extensions/neu_box.dart';
import 'extensions/Arrow_button.dart';
class lvl_one extends StatefulWidget {
const lvl_one({Key key}) : super(key: key);
#override
State<lvl_one> createState() => _lvl_oneState();
}
class _lvl_oneState extends State<lvl_one> {
//player variable
static double positionx = 0;
static double positiony = 1;
double time = 0;
double height = 0;
double vel = 0;
int duration = 50;
double initial_height = positiony;
void moveleft() {
setState(() {
if (positionx - 0.1 < -1) {
//nothing
} else {
positionx -= 0.1;
}
});
}
void moveright() {
setState(() {
if (positionx + 0.1 > 1) {
//nothing
} else {
positionx += 0.1;
}
});
}
void prejump() {
time = 0;
positiony = 1;
height = 0;
initial_height = 1;
duration = 50;
}
**void jump() {
setState(() {
prejump();
});
Timer.periodic(Duration(milliseconds: duration), (timer) {
time += 0.05;
height = -5 * time * time + 5 * time;
if (initial_height - height > 1) {
setState(() {
positiony = 1;
});
} else {
setState(() {
positiony = initial_height - height;
print("time is ${time}");
});
}
});
setState(() {
prejump();
});
}**
#override
Widget build(BuildContext context) {
double size = MediaQuery
.of(context)
.size
.width;
return SafeArea(
child: Column(
children: [
Expanded(flex: 3,
child: Container(
width: size, color: Colors.purple,
child: Stack(
children: [
player(positionx: positionx, positiony: positiony,),
],
),
)),
Container(height: 10, color: Colors.blueGrey,),
Expanded(flex: 1,
child: Container(
width: size, color: Colors.pink,
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
SizedBox(height: 50,
width: 50,
child: NeuBox(
child: Icon(Icons.arrow_left), function: moveleft,)),
SizedBox(height: 50,
width: 50,
**child: NeuBox(child: Icon(Icons.arrow_drop_up_outlined),
function: jump,)),**
SizedBox(height: 50,
width: 50,
child: NeuBox(child: Icon(Icons.arrow_right_outlined),
function: moveright,)),
],
),
)),
],
),
);
}
}

Answer 1

Because you use Timer.periodic(.. inside your void jump() function and it will create a new timer every time you call it.
You can try to print something like this inside the callback function:
Timer.periodic(Duration(milliseconds: duration), (timer) {
print("time is ${time}");
time += 0.05;
...
You will soon figure out that the time += 0.5 which should be call one in every 50 milliseconds become called twice (or more).
One way is move the Timer.periodic into the initial state and use prejump to jump.
#override
void initState() {
Timer.periodic(Duration(milliseconds: duration), (timer) {
print("time is ${time}");
time += 0.05;
height = -5 * time * time + 5 * time;
if (initial_height - height > 1) {
setState(() {
positiony = 1;
});
} else {
setState(() {
positiony = initial_height - height;
});
}
});
super.initState();
}
void prejump() {
time = 0;
positiony = 1;
height = 0;
initial_height = 1;
duration = 50;
}
void jump() {
setState(() {
prejump();
});
}