getFirstVisibleDay sometimes returns wrong day.

[emanueleDiVizio]

I've got a button wich calls goToDate() and the date is calculated starting from getFirstVisibleDay(). The problem is that getFirstVisibleDay() sometimes returns a Calendar instance off by one day, which causes the calculation to fail.

[entropitor]

Can you provide more information? (on how to recreate the bug)

How many days are you showing?
What are you doing before the bug occurs?
Are you sure that there is not even a tiny little part of the day showing? (there's still a bug where on swiping the library gets stuck between 2 days)

[emanueleDiVizio]

Right, sorry about that, here's the code:

@Override
    public boolean onOptionsItemSelected(MenuItem item) {
        Calendar firstday = mWeekView.getFirstVisibleDay();
        switch (item.getItemId()) {
            #(...)
            case R.id.action_fw:
                Calendar nextdate = (Calendar) firstday.clone();
                if(nextdate.get(Calendar.DAY_OF_YEAR) == firstday.get(Calendar.DAY_OF_YEAR)){
                    nextdate.add(Calendar.DAY_OF_YEAR, 1);
                }
                while (nextdate.get(Calendar.DAY_OF_WEEK) != Calendar.MONDAY) {
                    nextdate.add(Calendar.DAY_OF_YEAR, 1);
                }
                mWeekView.goToDate(nextdate);
                return true;
            #(...)
            }
        return super.onOptionsItemSelected(item);
    }

The code makes the weekView go to the next monday.
I don't think that a part of the previous day is showing because it goes to it with goToDate().
I am showing 6 days.
You need a few clicks to recreate the bug.

Thanks a lot.

Also, this same code doesn't work when put in onCreate, the view stops between the prev and the current day.

[entropitor]

Hmm, this is definitly weird. It only seems to happen when going forward, not when going backwards (I have tested it with my code which is similair, but supports backwards movement too).

Maybe the ceil from https://github.com/alamkanak/Android-Week-View/blob/master/library/src/main/java/com/alamkanak/weekview/WeekView.java#L392 has to do with it. I'm not sure but I'm guessing using Math.round there might fix this. Needs testing.

(I'm also guessing #53 will fix the onCreate thing. I don't have commit access so @alamkanak will have to merge that PR)

[Hugo-Pereira]

replace

int leftDaysWithGaps = (int) -(Math.ceil((mCurrentOrigin.x+ getColumnGap()) / (mWidthPerDay + mColumnGap)));
float startFromPixel = mCurrentOrigin.x + (mWidthPerDay + mColumnGap) * leftDaysWithGaps +
                mHeaderColumnWidth;

with

int leftDaysWithGaps = -(Math.round(mCurrentOrigin.x / (mWidthPerDay + mColumnGap)));
float startFromPixel = mCurrentOrigin.x + (mWidthPerDay + mColumnGap) * (leftDaysWithGaps-1) +
                mHeaderColumnWidth;

Tell me if this helps, I have been messing around with the library for a while now :\

[entropitor]

While testing, I think the bug lies within goToDate and not in getFirstVisibleDay.

@hellchoseme can you test my PR to see if it works for you?
(git clone this project from your app's root directory, merge my PR, add include(':weekview:library') to your settings.gradle and add a compile project(':weekview:library') instead of the compile 'com.github.almakanak:android-week-view:version-number'

[emanueleDiVizio]

I merged your PR, it's still not working. Although the bug appears after a few more clicks than before.

[entropitor]

Hmm, that's annoying. I'll take another look. I think it has something to do with numerical math stuff, so it's going to be annoying to debug :(

[entropitor]

@hellchoseme I tried to reproduce the bug, but I can scroll all the way too June without it ever getting stuck. I'm not sure how to fix the bug (if it's even in the library/PR) without reproducing. Can you maybe provide more information on your setup?

• How many days are you showing (still 6)?
• What day are you testing this
• On what day is it returning the wrong value?
• Any more information that you might think is relevant.

[entropitor]

@hellchoseme I think it's fixed with my 2nd commit :D

[emanueleDiVizio]

Hi I'm still having some issues. Sometimes getFirstVisibleDay() returns the day before. Also, I'm having a strange issue with this code:

Calendar nextdate = mWeekView.getFirstVisibleDay();
                nextdate.add(Calendar.DAY_OF_YEAR, 1);
                while (nextdate.get(Calendar.DAY_OF_WEEK) != Calendar.MONDAY) {
                    nextdate.add(Calendar.DAY_OF_YEAR, 1);
                }
                mWeekView.goToDate(nextdate);

I'm showing 5 days, and I'm trying to go from monday to monday. Sometimes it returns Sunday.

Sometimes the DAY_OF_WEEK value is different than the date displayed in time variable (expressed in milliseconds), ultimately breaking my code. Any clues on what could cause this behaviour? Thanks

[entropitor]

Have you tried me latest commit too?

[emanueleDiVizio]

I don't think, I'm on last alamkanak's merge. I'll try tomorrow.