/**************************************************************************** ** ** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies). ** All rights reserved. ** Contact: Nokia Corporation (qt-info@nokia.com) ** ** This file is part of the documentation of the Qt Toolkit. ** ** $QT_BEGIN_LICENSE:FDL$ ** GNU Free Documentation License ** Alternatively, this file may be used under the terms of the GNU Free ** Documentation License version 1.3 as published by the Free Software ** Foundation and appearing in the file included in the packaging of ** this file. ** ** Other Usage ** Alternatively, this file may be used in accordance with the terms ** and conditions contained in a signed written agreement between you ** and Nokia. ** ** ** ** ** $QT_END_LICENSE$ ** ****************************************************************************/ /*! \title Calendar Widget Example \example widgets/calendarwidget The Calendar Widget example shows use of \c QCalendarWidget. \image calendarwidgetexample.png QCalendarWidget displays one calendar month at a time and lets the user select a date. The calendar consists of four components: a navigation bar that lets the user change the month that is displayed, a grid where each cell represents one day in the month, and two headers that display weekday names and week numbers. The Calendar Widget example displays a QCalendarWidget and lets the user configure its appearance and behavior using \l{QComboBox}es, \l{QCheckBox}es, and \l{QDateEdit}s. In addition, the user can influence the formatting of individual dates and headers. The properties of the QCalendarWidget are summarized in the table below. \table \header \o Property \o Description \row \o \l{QCalendarWidget::}{selectedDate} \o The currently selected date. \row \o \l{QCalendarWidget::}{minimumDate} \o The earliest date that can be selected. \row \o \l{QCalendarWidget::}{maximumDate} \o The latest date that can be selected. \row \o \l{QCalendarWidget::}{firstDayOfWeek} \o The day that is displayed as the first day of the week (usually Sunday or Monday). \row \o \l{QCalendarWidget::}{gridVisible} \o Whether the grid should be shown. \row \o \l{QCalendarWidget::}{selectionMode} \o Whether the user can select a date or not. \row \o \l{QCalendarWidget::}{horizontalHeaderFormat} \o The format of the day names in the horizontal header (e.g., "M", "Mon", or "Monday"). \row \o \l{QCalendarWidget::}{verticalHeaderFormat} \o The format of the vertical header. \row \o \l{QCalendarWidget::}{navigationBarVisible} \o Whether the navigation bar at the top of the calendar widget is shown. \endtable The example consists of one class, \c Window, which creates and lays out the QCalendarWidget and the other widgets that let the user configure the QCalendarWidget. \section1 Window Class Definition Here is the definition of the \c Window class: \snippet examples/widgets/calendarwidget/window.h 0 \dots \snippet examples/widgets/calendarwidget/window.h 1 As is often the case with classes that represent self-contained windows, most of the API is private. We will review the private members as we stumble upon them in the implementation. \section1 Window Class Implementation Let's now review the class implementation, starting with the constructor: \snippet examples/widgets/calendarwidget/window.cpp 0 We start by creating the four \l{QGroupBox}es and their child widgets (including the QCalendarWidget) using four private \c create...GroupBox() functions, described below. Then we arrange the group boxes in a QGridLayout. We set the grid layout's resize policy to QLayout::SetFixedSize to prevent the user from resizing the window. In that mode, the window's size is set automatically by QGridLayout based on the size hints of its contents widgets. To ensure that the window isn't automatically resized every time we change a property of the QCalendarWidget (e.g., hiding the navigation bar, trhe vertical header, or the grid), we set the minimum height of row 0 and the minimum width of column 0 to the initial size of the QCalendarWidget. Let's move on to the \c createPreviewGroupBox() function: \snippet examples/widgets/calendarwidget/window.cpp 9 The \gui Preview group box contains only one widget: the QCalendarWidget. We set it up, connect its \l{QCalendarWidget::}{currentPageChanged()} signal to our \c reformatCalendarPage() slot to make sure that every new page gets the formatting specified by the user. The \c createGeneralOptionsGroupBox() function is somewhat large and several widgets are set up the same way; we look at parts of its implementation here and skip the rest: \snippet examples/widgets/calendarwidget/window.cpp 10 \dots We start with the setup of the \gui{Week starts on} combobox. This combobox controls which day should be displayed as the first day of the week. The QComboBox class lets us attach user data as a QVariant to each item. The data can later be retrieved with QComboBox's \l{QComboBox::}{itemData()} function. QVariant doesn't directly support the Qt::DayOfWeek data type, but it supports \c int, and C++ will happily convert any enum value to \c int. \dots \snippet examples/widgets/calendarwidget/window.cpp 11 \dots After creating the widgets, we connect the signals and slots. We connect the comboboxes to private slots of \c Window or to public slots provided by QComboBox. \dots \snippet examples/widgets/calendarwidget/window.cpp 12 At the end of the function, we call the slots that update the calendar to ensure that the QCalendarWidget is synchronized with the other widgets on startup. Let's now take a look at the \c createDatesGroupBox() private function: \snippet examples/widgets/calendarwidget/window.cpp 13 In this function, we create the \gui {Minimum Date}, \gui {Maximum Date}, and \gui {Current Date} editor widgets, which control the calendar's minimum, maximum, and selected dates. The calendar's minimum and maximum dates have already been set in \c createPrivewGroupBox(); we can then set the widgets default values to the calendars values. \snippet examples/widgets/calendarwidget/window.cpp 14 \dots \snippet examples/widgets/calendarwidget/window.cpp 15 We connect the \c currentDateEdit's \l{QDateEdit::}{dateChanged()} signal directly to the calendar's \l{QCalendarWidget::}{setSelectedDate()} slot. When the calendar's selected date changes, either as a result of a user action or programmatically, our \c selectedDateChanged() slot updates the \gui {Current Date} editor. We also need to react when the user changes the \gui{Minimum Date} and \gui{Maximum Date} editors. Here is the \c createTextFormatsGroup() function: \snippet examples/widgets/calendarwidget/window.cpp 16 We set up the \gui {Weekday Color} and \gui {Weekend Color} comboboxes using \c createColorCombo(), which instantiates a QComboBox and populates it with colors ("Red", "Blue", etc.). \snippet examples/widgets/calendarwidget/window.cpp 17 The \gui {Header Text Format} combobox lets the user change the text format (bold, italic, or plain) used for horizontal and vertical headers. The \gui {First Friday in blue} and \gui {May 1 in red} check box affect the rendering of specific dates. \snippet examples/widgets/calendarwidget/window.cpp 18 We connect the check boxes and comboboxes to various private slots. The \gui {First Friday in blue} and \gui {May 1 in red} check boxes are both connected to \c reformatCalendarPage(), which is also called when the calendar switches month. \dots \snippet examples/widgets/calendarwidget/window.cpp 19 At the end of \c createTextFormatsGroupBox(), we call private slots to synchronize the QCalendarWidget with the other widgets. We're now done reviewing the four \c create...GroupBox() functions. Let's now take a look at the other private functions and slots. \snippet examples/widgets/calendarwidget/window.cpp 20 In \c createColorCombo(), we create a combobox and populate it with standard colors. The second argument to QComboBox::addItem() is a QVariant storing user data (in this case, QColor objects). This function was used to set up the \gui {Weekday Color} and \gui {Weekend Color} comboboxes. \snippet examples/widgets/calendarwidget/window.cpp 1 When the user changes the \gui {Week starts on} combobox's value, \c firstDayChanged() is invoked with the index of the combobox's new value. We retrieve the custom data item associated with the new current item using \l{QComboBox::}{itemData()} and cast it to a Qt::DayOfWeek. \c selectionModeChanged(), \c horizontalHeaderChanged(), and \c verticalHeaderChanged() are very similar to \c firstDayChanged(), so they are omitted. \snippet examples/widgets/calendarwidget/window.cpp 2 The \c selectedDateChanged() updates the \gui{Current Date} editor to reflect the current state of the QCalendarWidget. \snippet examples/widgets/calendarwidget/window.cpp 3 When the user changes the minimum date, we tell the QCalenderWidget. We also update the \gui {Maximum Date} editor, because if the new minimum date is later than the current maximum date, QCalendarWidget will automatically adapt its maximum date to avoid a contradicting state. \snippet examples/widgets/calendarwidget/window.cpp 4 \c maximumDateChanged() is implemented similarly to \c minimumDateChanged(). \snippet examples/widgets/calendarwidget/window.cpp 5 Each combobox item has a QColor object as user data corresponding to the item's text. After fetching the colors from the comboboxes, we set the text format of each day of the week. The text format of a column in the calendar is given as a QTextCharFormat, which besides the foreground color lets us specify various character formatting information. In this example, we only show a subset of the possibilities. \snippet examples/widgets/calendarwidget/window.cpp 6 \c weekendFormatChanged() is the same as \c weekdayFormatChanged(), except that it affects Saturday and Sunday instead of Monday to Friday. \snippet examples/widgets/calendarwidget/window.cpp 7 The \c reformatHeaders() slot is called when the user changes the text format of the headers. We compare the current text of the \gui {Header Text Format} combobox to determine which format to apply. (An alternative would have been to store \l{QTextCharFormat} values alongside the combobox items.) \snippet examples/widgets/calendarwidget/window.cpp 8 In \c reformatCalendarPage(), we set the text format of the first Friday in the month and May 1 in the current year. The text formats that are actually used depend on which check boxes are checked. QCalendarWidget lets us set the text format of individual dates with the \l{QCalendarWidget::}{setDateTextFormat()}. We chose to set the dates when the calendar page changes, i.e., a new month is displayed. We check which of the \c mayFirstCheckBox and \c firstDayCheckBox, if any, are checked and set the text formats accordingly. */