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<title>Calendar Widget Example</title>
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<h1 align="center">Calendar Widget Example<br /><span class="subtitle"></span>
</h1>
<p>The Calendar Widget example shows use of <tt>QCalendarWidget</tt>.</p>
<p align="center"><img src="classpath:com/trolltech/images/jambicalendarwidget.png" /></p><p>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.</p>
<p>The Calendar Widget example displays a QCalendarWidget and lets the user configure its appearance and behavior using QComboBoxes, QCheckBoxes, and QDateEdits. In addition, the user can influence the formatting of individual dates and headers.</p>
<p>The properties of the QCalendarWidget are summarized in the table below.</p>
<p><table align="center" cellpadding="2" cellspacing="1" border="0">
<thead><tr valign="top" class="qt-style"><th>Property</th><th>Description</th></tr></thead>
<tr valign="top" class="odd"><td>selectedDate</td><td>The currently selected date.</td></tr>
<tr valign="top" class="even"><td>minimumDate</td><td>The earliest date that can be selected.</td></tr>
<tr valign="top" class="odd"><td>maximumDate</td><td>The latest date that can be selected.</td></tr>
<tr valign="top" class="even"><td>firstDayOfWeek</td><td>The day that is displayed as the first day of the week (usually Sunday or Monday).</td></tr>
<tr valign="top" class="odd"><td>gridVisible</td><td>Whether the grid should be shown.</td></tr>
<tr valign="top" class="even"><td>selectionMode</td><td>Whether the user can select a date or not.</td></tr>
<tr valign="top" class="odd"><td>horizontalHeaderFormat</td><td>The format of the day names in the horizontal header (e.g., "M", "Mon", or "Monday").</td></tr>
<tr valign="top" class="even"><td>verticalHeaderFormat</td><td>The format of the vertical header.</td></tr>
<tr valign="top" class="odd"><td>navigationBarVisible</td><td>Whether the navigation bar at the top of the calendar widget is shown.</td></tr>
</table></p>
<p>The example consists of one class, <tt>CalendarWidget</tt>, which creates and lays out the QCalendarWidget and the other widgets that let the user configure the QCalendarWidget.</p>
<a name="the-calendarwidget-class"></a>
<h2>The CalendarWidget Class</h2>
<p>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.</p>
<p>Here is the constructor of CalendarWidget:</p>
<pre> public CalendarWidget() {
createPreviewGroupBox();
createGeneralOptionsGroupBox();
createDatesGroupBox();
createTextFormatsGroupBox();
QGridLayout layout = new QGridLayout();
layout.addWidget(previewGroupBox, 0, 0);
layout.addWidget(generalOptionsGroupBox, 0, 1);
layout.addWidget(datesGroupBox, 1, 0);
layout.addWidget(textFormatsGroupBox, 1, 1);
layout.setSizeConstraint(QLayout.SizeConstraint.SetFixedSize);
setLayout(layout);
previewLayout.setRowMinimumHeight(0, calendar.sizeHint().height());
previewLayout.setColumnMinimumWidth(0, calendar.sizeHint().width());
setWindowTitle(tr("Calendar Widget"));
}</pre>
<p>We start by creating the four QGroupBoxes and their child widgets (including the QCalendarWidget) using four private <tt>create...GroupBox()</tt> methods, described below. Then we arrange the group boxes in a QGridLayout.</p>
<p>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.</p>
<p>To ensure that the window isn't automatically resized every time we change a property of the QCalendarWidget (e.g., hiding the navigation bar, the 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.</p>
<p>Let's move on to the <tt>createPreviewGroupBox()</tt> method:</p>
<pre> private void createPreviewGroupBox() {
previewGroupBox = new QGroupBox(tr("Preview"));
calendar = new QCalendarWidget();
calendar.setMinimumDate(new QDate(1900, 1, 1));
calendar.setMaximumDate(new QDate(3000, 1, 1));
calendar.setGridVisible(true);
calendar.currentPageChanged.connect(this, "reformatCalendarPage()");
previewLayout = new QGridLayout();
previewLayout.addWidget(calendar, 0, 0, Qt.AlignmentFlag.AlignCenter);
previewGroupBox.setLayout(previewLayout);
}</pre>
<p>The <b>Preview group box</b> contains only one widget: the QCalendarWidget. We set it up, connect its currentPageChanged() signal to our <tt>reformatCalendarPage()</tt> slot to make sure that every new page gets the formatting specified by the user.</p>
<p>The <tt>createGeneralOptionsGroupBox()</tt> method is somewhat large and several widgets are set up the same way; we look at parts of its implementation here and skip the rest:</p>
<pre> private void createGeneralOptionsGroupBox() {
generalOptionsGroupBox = new QGroupBox(tr("General Options"));
localeCombo = new QComboBox();
int curLocaleIndex = -1;
int index = 0;
for (QLocale.Language lang : QLocale.Language.values()) {
List<QLocale.Country> countries = QLocale.countriesForLanguage(lang);
for (int i = 0; i < countries.size(); ++i) {
QLocale.Country country = countries.get(i);
String label = QLocale.languageToString(lang);
label += "/";
label += QLocale.countryToString(country);
QLocale locale = new QLocale(lang, country);
if (this.locale().language() == lang && this.locale().country() == country)
curLocaleIndex = index;
localeCombo.addItem(label, locale);
++index;
}
}
if (curLocaleIndex != -1)
localeCombo.setCurrentIndex(curLocaleIndex);
localeLabel = new QLabel(tr("&Locale"));
localeLabel.setBuddy(localeCombo);</pre>
<p>The calendar widget can display the numbers of dates and years in various languages and locales. The current language/locale used by the calendar is specified by a QLocale. We loop through all possible pairs of languages and locales and add them to the <b>Locale combo box</b>, from which the user selects the current locale of the calendar widget.</p>
<p>Note that the QLocale object for each pair is stored in each combo box item's user data. We can later retrieve this object with QComboBox's itemData() when a new item is selected.</p>
<pre> firstDayCombo = new QComboBox();
firstDayCombo.addItem(tr("Sunday"), Qt.DayOfWeek.Sunday);
firstDayCombo.addItem(tr("Monday"), Qt.DayOfWeek.Monday);
firstDayCombo.addItem(tr("Tuesday"), Qt.DayOfWeek.Tuesday);
firstDayCombo.addItem(tr("Wednesday"), Qt.DayOfWeek.Wednesday);
firstDayCombo.addItem(tr("Thursday"), Qt.DayOfWeek.Thursday);
firstDayCombo.addItem(tr("Friday"), Qt.DayOfWeek.Friday);
firstDayCombo.addItem(tr("Saturday"), Qt.DayOfWeek.Saturday);
firstDayLabel = new QLabel(tr("Wee&k starts on:"));
firstDayLabel.setBuddy(firstDayCombo);
...</pre>
<p>The <b>Week starts on</b> combobox controls which day should be displayed as the first day of the week.</p>
<pre> ...
localeCombo.currentIndexChanged.connect(this, "localeChanged(int)");
firstDayCombo.currentIndexChanged.connect(this, "firstDayChanged(int)");
selectionModeCombo.currentIndexChanged.connect(this, "selectionModeChanged(int)");
gridCheckBox.toggled.connect(calendar, "setGridVisible(boolean)");
navigationCheckBox.toggled.connect(calendar, "setNavigationBarVisible(boolean)");
horizontalHeaderCombo.currentIndexChanged.connect(this, "horizontalHeaderChanged(int)");
verticalHeaderCombo.currentIndexChanged.connect(this, "verticalHeaderChanged(int)");
...</pre>
<p>After creating the widgets, we connect the signals and slots. We connect the comboboxes to private slots of <tt>Window</tt> or to public slots provided by QCalendarWidget.</p>
<pre> ...
firstDayChanged(firstDayCombo.currentIndex());
selectionModeChanged(selectionModeCombo.currentIndex());
horizontalHeaderChanged(horizontalHeaderCombo.currentIndex());
verticalHeaderChanged(verticalHeaderCombo.currentIndex());
}</pre>
<p>At the end of the method, we call the slots that update the calendar to ensure that the QCalendarWidget is synchronized with the other widgets on startup.</p>
<p>Let's now take a look at the <tt>createDatesGroupBox()</tt> private method:</p>
<pre> private void createDatesGroupBox() {
datesGroupBox = new QGroupBox(tr("Dates"));
minimumDateEdit = new QDateEdit();
minimumDateEdit.setDisplayFormat("MMM d, yyyy");
minimumDateEdit.setDateRange(calendar.minimumDate(),
calendar.maximumDate());
minimumDateEdit.setDate(calendar.minimumDate());
minimumDateLabel = new QLabel(tr("&Minimum Date:"));
minimumDateLabel.setBuddy(minimumDateEdit);
currentDateEdit = new QDateEdit();
currentDateEdit.setDisplayFormat("MMM d, yyyy");
currentDateEdit.setDate(calendar.selectedDate());
currentDateEdit.setDateRange(calendar.minimumDate(),
calendar.maximumDate());
currentDateLabel = new QLabel(tr("&Current Date:"));
currentDateLabel.setBuddy(currentDateEdit);
maximumDateEdit = new QDateEdit();
maximumDateEdit.setDisplayFormat("MMM d, yyyy");
maximumDateEdit.setDateRange(calendar.minimumDate(),
calendar.maximumDate());
maximumDateEdit.setDate(calendar.maximumDate());
maximumDateLabel = new QLabel(tr("Ma&ximum Date:"));
maximumDateLabel.setBuddy(maximumDateEdit);</pre>
<p>In this method, we create the <b>Minimum Date</b>, <b>Maximum Date</b>, and <b>Current Date</b> editor widgets, which control the calendar's minimum, maximum, and selected dates. The calendar's minimum and maximum dates have already been set in <tt>createPrivewGroupBox()</tt>; we can then set the widgets default values to the calendars values.</p>
<pre> currentDateEdit.dateChanged.connect(calendar, "setSelectedDate(QDate)");
calendar.selectionChanged.connect(this, "selectedDateChanged()");
minimumDateEdit.dateChanged.connect(this, "minimumDateChanged(QDate)");
maximumDateEdit.dateChanged.connect(this, "maximumDateChanged(QDate)");
...
}</pre>
<p>We connect the <tt>currentDateEdit</tt>'s dateChanged() signal directly to the calendar's setSelectedDate() slot. When the calendar's selected date changes, either as a result of a user action or programmatically, our <tt>selectedDateChanged()</tt> slot updates the <b>Current Date</b> editor. We also need to react when the user changes the <b>Minimum Date</b> and <b>Maximum Date</b> editors.</p>
<p>Here is the <tt>createTextFormatsGroup()</tt> method:</p>
<pre> private void createTextFormatsGroupBox() {
textFormatsGroupBox = new QGroupBox(tr("Text Formats"));
weekdayColorCombo = createColorComboBox();
weekdayColorCombo.setCurrentIndex(
weekdayColorCombo.findText(tr("Black")));
weekdayColorLabel = new QLabel(tr("&Weekday color:"));
weekdayColorLabel.setBuddy(weekdayColorCombo);
weekendColorCombo = createColorComboBox();
weekendColorCombo.setCurrentIndex(
weekendColorCombo.findText(tr("Red")));
weekendColorLabel = new QLabel(tr("Week&end color:"));
weekendColorLabel.setBuddy(weekendColorCombo);</pre>
<p>We set up the <b>Weekday Color</b> and <b>Weekend Color</b> comboboxes using <tt>createColorCombo()</tt>, which instantiates a QComboBox and populates it with colors ("Red", "Blue", etc.).</p>
<pre> headerTextFormatCombo = new QComboBox();
headerTextFormatCombo.addItem(tr("Bold"));
headerTextFormatCombo.addItem(tr("Italic"));
headerTextFormatCombo.addItem(tr("Plain"));
headerTextFormatLabel = new QLabel(tr("&Header text:"));
headerTextFormatLabel.setBuddy(headerTextFormatCombo);
firstFridayCheckBox = new QCheckBox(tr("&First Friday in blue"));
mayFirstCheckBox = new QCheckBox(tr("May &1 in red"));</pre>
<p>The <b>Header Text Format</b> combobox lets the user change the text format (bold, italic, or plain) used for horizontal and vertical headers. The <b>First Friday in blue</b> and <b>May 1 in red</b> check box affect the rendering of specific dates.</p>
<pre> weekdayColorCombo.currentIndexChanged.connect(this, "weekdayFormatChanged()");
weekendColorCombo.currentIndexChanged.connect(this, "weekendFormatChanged()");
headerTextFormatCombo.currentStringChanged.connect(this, "reformatHeaders()");
firstFridayCheckBox.toggled.connect(this, "reformatCalendarPage()");
mayFirstCheckBox.toggled.connect(this, "reformatCalendarPage()");</pre>
<p>We connect the check boxes and comboboxes to various private slots. The <b>First Friday in blue</b> and <b>May 1 in red</b> check boxes are both connected to <tt>reformatCalendarPage()</tt>, which is also called when the calendar switches month.</p>
<pre> ...
reformatHeaders();
reformatCalendarPage();
}</pre>
<p>At the end of <tt>createTextFormatsGroupBox()</tt>, we call private slots to synchronize the QCalendarWidget with the other widgets.</p>
<p>We're now done reviewing the four <tt>create...GroupBox()</tt> methods. Let's now take a look at the other private methods and slots.</p>
<pre> private QComboBox createColorComboBox() {
QComboBox comboBox = new QComboBox();
comboBox.addItem(tr("Red"), new QColor(Qt.GlobalColor.red));
comboBox.addItem(tr("Blue"), new QColor(Qt.GlobalColor.blue));
comboBox.addItem(tr("Black"), new QColor(Qt.GlobalColor.black));
comboBox.addItem(tr("Magenta"), new QColor(Qt.GlobalColor.magenta));
return comboBox;
}</pre>
<p>In <tt>createColorCombo()</tt>, we create a combobox and populate it with standard colors. The second argument to QComboBox::addItem() is user data stored for each item (in this case, QColor objects).</p>
<p>This method was used to set up the <b>Weekday Color</b> and <b>Weekend Color</b> comboboxes.</p>
<pre> private void firstDayChanged(int index) {
calendar.setFirstDayOfWeek((Qt.DayOfWeek) firstDayCombo.itemData(index));
}</pre>
<p>When the user changes the <b>Week starts on</b> combobox's value, <tt>firstDayChanged()</tt> is invoked with the index of the combobox's new value. We retrieve the custom data item associated with the new current item using itemData() and cast it to a Qt::DayOfWeek.</p>
<p><tt>selectionModeChanged()</tt>, <tt>horizontalHeaderChanged()</tt>, and <tt>verticalHeaderChanged()</tt> are very similar to <tt>firstDayChanged()</tt>, so they are omitted.</p>
<pre> private void selectedDateChanged() {
currentDateEdit.setDate(calendar.selectedDate());
}</pre>
<p>The <tt>selectedDateChanged()</tt> updates the <b>Current Date</b> editor to reflect the current state of the QCalendarWidget.</p>
<pre> private void minimumDateChanged(QDate date) {
calendar.setMinimumDate(date);
maximumDateEdit.setDate(calendar.maximumDate());
}</pre>
<p>When the user changes the minimum date, we tell the QCalenderWidget. We also update the <b>Maximum Date</b> 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.</p>
<pre> private void maximumDateChanged(QDate date) {
calendar.setMaximumDate(date);
minimumDateEdit.setDate(calendar.minimumDate());
}</pre>
<p><tt>maximumDateChanged()</tt> is implemented similarly to <tt>minimumDateChanged()</tt>.</p>
<pre> private void weekdayFormatChanged() {
QTextCharFormat format = new QTextCharFormat();
format.setForeground(new QBrush((QColor) weekdayColorCombo.itemData(weekdayColorCombo.currentIndex())));
calendar.setWeekdayTextFormat(Qt.DayOfWeek.Monday, format);
calendar.setWeekdayTextFormat(Qt.DayOfWeek.Tuesday, format);
calendar.setWeekdayTextFormat(Qt.DayOfWeek.Wednesday, format);
calendar.setWeekdayTextFormat(Qt.DayOfWeek.Thursday, format);
calendar.setWeekdayTextFormat(Qt.DayOfWeek.Friday, format);
}</pre>
<p>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.</p>
<p>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.</p>
<pre> private void weekendFormatChanged() {
QTextCharFormat format = new QTextCharFormat();
format.setForeground(new QBrush((QColor) weekendColorCombo.itemData(weekendColorCombo.currentIndex())));
calendar.setWeekdayTextFormat(Qt.DayOfWeek.Saturday, format);
calendar.setWeekdayTextFormat(Qt.DayOfWeek.Sunday, format);
}</pre>
<p><tt>weekendFormatChanged()</tt> is the same as <tt>weekdayFormatChanged()</tt>, except that it affects Saturday and Sunday instead of Monday to Friday.</p>
<pre> private void reformatHeaders() {
String text = headerTextFormatCombo.currentText();
QTextCharFormat format = new QTextCharFormat();
if (text.equals(tr("Bold"))) {
format.setFontWeight(QFont.Weight.Bold.value());
} else if (text.equals(tr("Italic"))) {
format.setFontItalic(true);
} else if (text.equals(tr("Green"))) {
format.setForeground(new QBrush(new QColor(Qt.GlobalColor.green)));
}
calendar.setHeaderTextFormat(format);
}</pre>
<p>The <tt>reformatHeaders()</tt> slot is called when the user changes the text format of the headers. We compare the current text of the <b>Header Text Format</b> combobox to determine which format to apply. (An alternative would have been to store QTextCharFormat values alongside the combobox items.)</p>
<pre> private void reformatCalendarPage() {
QTextCharFormat mayFirstFormat = new QTextCharFormat();
if (mayFirstCheckBox.isChecked())
mayFirstFormat.setForeground(new QBrush(new QColor(Qt.GlobalColor.red)));
QTextCharFormat firstFridayFormat = new QTextCharFormat();
if (firstFridayCheckBox.isChecked())
firstFridayFormat.setForeground(new QBrush(new QColor(Qt.GlobalColor.blue)));
QDate date = new QDate(calendar.yearShown(), calendar.monthShown(), 1);
calendar.setDateTextFormat(new QDate(date.year(), 5, 1), mayFirstFormat);
date.setDate(date.year(), date.month(), 1);
while (date.dayOfWeek() != Qt.DayOfWeek.Friday.value())
date = date.addDays(1);
calendar.setDateTextFormat(date, firstFridayFormat);
}</pre>
<p>In <tt>reformatCalendarPage()</tt>, 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.</p>
<p>QCalendarWidget lets us set the text format of individual dates with the setDateTextFormat(). We chose to set the dates when the calendar page changes, i.e., a new month is displayed. We check which of the <tt>mayFirstCheckBox</tt> and <tt>firstDayCheckBox</tt>, if any, are checked and set the text formats accordingly.</p>
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