Clash Royale CLAN TAG#URR8PPP

Issue subtracting days from calendar

I have an horizontal calendar in my application. So I have implemented the following library https://github.com/Mulham-Raee/Horizontal-Calendar
I also have implemented my own back and forward button.

Pressing back takes back one day from current date and forward takes one day forward. Suppose today is 10th August and I scrolled horizontally till 15th July without pressing back or forward button. Now if I press back button instead of going to 14th July, I go back to 9th August.

Following is my code

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">

<com.myapplication.HorizontalCalendarView
android:id="@+id/calendarView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:selectedDateBackground="@drawable/selected_date"
/>

<Button
android:id="@+id/back"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginStart="8dp"
android:text="Back"
app:layout_constraintBottom_toTopOf="@+id/calendarView"
app:layout_constraintStart_toStartOf="parent" />

<Button
android:id="@+id/forward"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginEnd="16dp"
android:text="Forward"
app:layout_constraintBottom_toTopOf="@+id/calendarView"
app:layout_constraintEnd_toEndOf="parent" />

</android.support.constraint.ConstraintLayout>


Kotlin code:

class MainActivity : AppCompatActivity()

private var counter: Int = 0

override fun onCreate(savedInstanceState: Bundle?)
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main_2)

val format1 = SimpleDateFormat("yyyy-MM-dd", Locale.US)
val currentDate = format1.format(Calendar.getInstance().time)

Toast.makeText(this,currentDate.toString(),Toast.LENGTH_LONG).show()

val startDate = Calendar.getInstance()
startDate.add(Calendar.MONTH, -10)


val endDate = Calendar.getInstance()
endDate.add(Calendar.MONTH, 30)

val horizontalCalendar = HorizontalCalendar.Builder(this, R.id.calendarView)
.range(startDate, endDate)
.datesNumberOnScreen(7)
.build()


horizontalCalendar.setCalendarListener(object : HorizontalCalendarListener()
override fun onDateSelected(date: Calendar, position: Int)
val selectedDate = format1.format(date.time)

Toast.makeText(this@MainActivity,
"Pritish"+SimpleDateFormat("MMMM yyyy", Locale.US).format(date.time),
Toast.LENGTH_SHORT).show()

if(format1.parse(selectedDate).before(format1.parse(currentDate)))
Toast.makeText(this@MainActivity,"Cannot selecte previous date",Toast.LENGTH_LONG).show()
else
Toast.makeText(this@MainActivity,
selectedDate
,Toast.LENGTH_LONG).show()



override fun onCalendarScroll(calendarView: HorizontalCalendarView,
dx: Int, dy: Int)


Log.i("Pritish",dx.toString()+dy.toString())


counter += if(dx<0)
-1
else
1




override fun onDateLongClicked(date: Calendar, position: Int): Boolean
return true

)

val cal = Calendar.getInstance()

back.setOnClickListener

cal.add(Calendar.DAY_OF_MONTH,counter-1)
counter = 0
horizontalCalendar.selectDate(cal,false)
horizontalCalendar.refresh()



forward.setOnClickListener
cal.add(Calendar.DAY_OF_MONTH,counter+1)
counter = 0
horizontalCalendar.selectDate(cal,false)
horizontalCalendar.refresh()





onDateSelected

3 Answers
3

It looks like it's possible that onDateSelected will get fired during scroll and that you can use that plus a simple +1/-1, but you'll have to try that to see if it works -- it's hard to validate just based on looking at the code for the library.

onDateSelected

There's a solution with the code you have provided. Try keeping a global counter of the number of swipes (-1 for a back swipe and +1 for a forward swipe). Every time a swipe event happens, update that counter.

Then, in your back and forward listeners, utilize that counter. For example, if you had swiped back 5 days, COUNTER = -5. Then if the user clicks the back button,

COUNTER = -5

cal.add(Calendar.DAY_OF_MONTH, (COUNTER-1))

cal.add(Calendar.DAY_OF_MONTH, (COUNTER-1))

Remember to reset your counter to 0 every time after a button click.

To combine that with onCalendarScroll, you can set another global variable that tracks the total dx change. When the dx hits a certain value, you know that a full swipe has been made, so the counter +/- 1. Here's some code to illustrate:

onCalendarScroll

private var dx_tracker: Int = 0
private var counter: Int = 0
private SWIPE_VAL = <your tested value>

override fun onCalendarScroll(calendarView: HorizontalCalendarView,
dx: Int, dy: Int)
Log.i("Pritish", dx.toString() + dy.toString())
dx_tracker += dx

if(dx_tracker >= SWIPE_VAL)
counter += 1;
dx_tracker = 0;

else if(dx_tracker <= -SWIPE_VAL)
counter -= 1;
dx_tracker = 0;




You need to set date in cal instance.

I didn't find any syntax which set cal instance.

you have defined cal instance like this

val cal = Calendar.getInstance()


Your counter is not increasing. So, it will take you to previous date. cal always stores 10th August, If you have not pressed any buttons.

You can reset cal instance onDateSelected method

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