[Development] Qt Quick Controls Calendar

Mark Gaiser markg85 at gmail.com
Sat Dec 21 19:50:30 CET 2013

On Fri, Dec 6, 2013 at 4:11 PM, Mitch Curtis <mitch.curtis at digia.com> wrote:
> On 12/06/2013 03:08 PM, Mark Gaiser wrote:
>> On Fri, Dec 6, 2013 at 2:02 PM, Mitch Curtis <mitch.curtis at digia.com>
>> wrote:
>>> Hello.
>>> At the beginning of this year I started work on a Calendar for Qt Quick
>>> Controls as a sort of side project. After removing the "WIP" from the
>>> commit message, I got some feedback from developers who either a) had
>>> also wrote a Calendar for KDE stuff or b) suggested I ask for feedback
>>> from plasma-devel. Rather than add to the already massive list of patch
>>> sets for that change, I thought it would be better to truly open up the
>>> Calendar for contributions before it goes in by creating a WIP branch
>>> for it in the Qt Quick Controls repo [1]:
>>> wip/calendar
>>> It'll be a throwaway branch, so every commit must be atomic and follow
>>> all of the normal Qt commit policies [2][3]. At the end, we'll resubmit
>>> every individual change to qtquickcontrols' dev branch.
> I've been told that this is incorrect; the correct statement is:
> "even though this is a throw-away branch (whose commits will be re-submitted
> to dev individually), the usual policies should be followed"
>>> Please feel free to submit patches or provide feedback on what's already
>>> there. For example, it has already been suggested that there should be a
>>> C++ backend for the models, dates, etc.
>>> Cheers.
>>> [1]
>>> https://qt.gitorious.org/qt/qtquickcontrols/source/4c3196c979d9a7f46b3f37b14140026dd74bf79a
>>> [2] http://qt-project.org/wiki/Branch-Guidelines
>>> [3] http://qt-project.org/wiki/Commit_Policy
>> Hi Mitch,
>> It's awesome that you pull in the KDE plasma folks. I wonder who gave
>> you that idea? ;)
>> Below is my "feature" list that i'd like to have in that calendar.
>> Since i have some experience in that area i will try to help out as
>> much as i can.
>> -- QML part --
>> * Controls for the calendar grid
>> * Controls for next/forward or just a few functions. This should at
>> least have a nextMonth/previousMonth. Perhaps also nextYear and
>> previousYear for convenience.
>> * Controls for the day names (mon, tue, wed, thu, fri, sat, sun). And
>> the ability to change the name to shorter/longer variants.
>> * Controls for the weeknumbers that are shown in the grid.
>> As far as i understand the QML code, all but the weeknumbers are in.
> Yep.
>> -- Locale --
>> In KDE there was already an issue with differences between the
>> JavaScript date object and the QDate object. I don't know the fine
>> details here, someone else will probably fill that in i hope. I know
>> there where issues, just not what exactly.
> From the testing that I did with it [1], it has some differences when it's a
> negative year, so the current implementation of the Calendar only allows
> positive years, up to the year 275759; a significantly smaller range than
> QDate [2].
>> -- C++ part --
>> This is the part where i really would like some feedback. I have a
>> general idea of how it should be done, but i don't know the details or
>> implications it might have.
>> It is my hope that calendar controls like Mitch is proposing now will
>> be extensive enough to simply swap the models to another backend.
>> Akonadi comes to mind. However, there should obviously be a
>> non-akonadi based version for default Qt usage.
>> My idea on that is as follows. Again, i don't know the implications of
>> it or if it's really viable to take this route. Feedback is very much
>> welcome here!
>> The calendar model should be based on a new model that provides some
>> default functionality and properties. I would say:
>> QAbstractCalendarModel : public QAbstractListModel { ... }
>> This model should provide the default - should be implemented -
>> properties:
>> * day -- INT number of the day in a current month
>> * isCurrentMonth -- returns true for the current month (aka, the month
>> you are viewing in the calendar). Returns false for the days before
>> and after the currently viewing month. Based on the position in the
>> grid you can then calculate if the entry where "isCurrentMonth"
>> returns false is before or after the current month.
>> * containsEvents -- true if the day contains events, false otherwise
>> "day" and "isCurrentMonth" should be convenience implemented in the
>> QAbstractCalendarModel.
>> Next there should be a model for core Qt calendar usage. Or in other
>> terms: no akonadi dependency.
>> That would be a class like:
>> QSimpleCalendarModel : public QAbstractCalendarModel { ... }
>> That class should probably have some basic storage in json files
>> somewhere? Or ini or sqlite or..? Just something so that it can be
>> used out of the box without any other requirements beyond Qt.
>> Till this point is what would probably go in Qt. Everything after this
>> line becomes Akonadi specific and should not be in Qt.
>> If a structure like the above is approved then Akonadi can be very
>> easily used in KDE with the Qt calendar components.
>> We'd just have to make out own QAbstractCalendarModel implementation
>> that uses akonadi data. That would be a class like:
>> (K)AconadiCalendarModel : public QAbstractCalendarModel { ... }
>> It can still use the base QAbstractCalendarModel implementation for
>> it's grid stuff and re-implement the "containsEvents" property to be
>> filled with data from akonadi.
> As you may know, John Layt has some calendar stuff in the works for 5.3 [3].
> It would be great to get his feedback, although I know he's quite busy.
>> Well, that's it for my idea thus far. I'm looking forward to some
>> opinions on this.
> [1]
> https://codereview.qt-project.org/#patch,sidebyside,73340,1,src/controls/Private/qquickrangeddate.cpp
> [2] http://doc-snapshot.qt-project.org/qt5-stable/qdate.html#details
> [3] http://qt-project.org/wiki/Qt-5-ICU#955c0120c32f7991db7d55a94df808c2


I hope some of the plasma folks can provide some feedback on the ideas
proposed in this thread.

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