Add a date range selector. Fixes #120.

src/Typica.pro

     webview.h \
     webelement.h \
     scale.h \
-    draglabel.h
+    draglabel.h \
+    daterangeselector.h
 SOURCES += typica.cpp \
     helpmenu.cpp \
     abouttypica.cpp \
     webview.cpp \
     webelement.cpp \
     scale.cpp \
-    draglabel.cpp
+    draglabel.cpp \
+    daterangeselector.cpp
 
 RESOURCES += \
     resources.qrc

src/daterangeselector.w

+@** A Widget for Selecting Date Ranges.
+
+\noindent Many of the reports in Typica operate over a range of dates. In these
+cases it should generally be possible to set that range to any arbitrary start
+or end, however there are some ranges that are commonly useful where it may be
+convenient to provide easy access to that range. While Qt provides a widget
+for selecting a single date, it does not provide a widget that allows two dates
+to be conveniently selected. One approach which Typica has previously taken is
+to simply use two |QDateEdit| widgets. This works, however validation that the
+range is valid must then be performed in every report that uses such an
+approach. Another down side to this is that changing either side of the date
+range is either going to result in a database query to obtain results in the
+new range or another button must be introduced to make setting a new range
+explicit. One typically wants to adjust both sides of the range at the same
+time and only have one trip to the database for the new data and increasing the
+number of controls required for each filter quickly creates a mess.
+
+The solution to this is the introduction of a new composite widget for
+selecting date ranges. The main widget consists of two parts. First there is a
+|QComboBox| which contains many common date ranges. A |QToolButton| is also
+provided for convenient one click access to the Custom range. Whether selected
+from the |QComboBox| or the |QToolButton|, selecting Custom creates a new pop
+up widget containing two |QCalendarWidget|s and a button to explicitly set the
+range. This button will not be available unless the selected ending date is not
+before the selected starting date.
+
+As the common use for the selected date is database operations, convenient
+access to the ISO 8601 string representation of these dates is provided.
+
+@(daterangeselector.h@>=
+
+#include <QComboBox>
+
+#ifndef TypicaDateRangeSelectorHeader
+#define TypicaDateRangeSelectorHeader
+
+class CustomDateRangePopup;
+
+class DateRangeSelector : public QWidget
+{
+	@[Q_OBJECT@]@;
+	public:@/
+		DateRangeSelector(QWidget *parent = NULL);
+		void setCustomRange(QVariant range);
+		Q_INVOKABLE QVariant currentRange();@/
+	@[signals@]:@/
+		void rangeUpdated(QVariant);
+	@[private slots@]:@/
+		void toggleCustom();
+		void popupHidden();
+		void updateRange(int index);@/
+	private:@/
+		QComboBox *quickSelector;
+		CustomDateRangePopup *customRangeSelector;
+		int lastIndex;
+};
+
+#endif
+
+@ Implementation details are in a different file.
+
+@(daterangeselector.cpp@>=
+#include <QCalendarWidget>
+#include <QPushButton>
+#include <QBoxLayout>
+#include <QLabel>
+#include <QToolButton>
+#include <QApplication>
+#include <QDesktopWidget>
+
+#include "daterangeselector.h"
+
+@<CustomDateRangePopup declaration@>
+@<CustomDateRangePopup implementation@>
+@<DateRangeSelector implementation@>
+
+#include "moc_daterangeselector.cpp"
+
+@ The custom range pop up is represented as a separate class which is not to be
+instantiated except by |DateRangeSelector|.
+
+@<CustomDateRangePopup declaration@>=
+class CustomDateRangePopup : public QWidget
+{
+	@[Q_OBJECT@]@;
+	public:@/
+		CustomDateRangePopup(QWidget *parent = NULL);@/
+	@[public slots@]:@/
+		void applyRange();@/
+	@[signals@]:@/
+		void hidingPopup();@/
+	protected:@/
+		virtual void hideEvent(QHideEvent *event);@/
+	@[private slots@]:@/
+		void validateRange();@/
+	private:@/
+		QCalendarWidget *startDateSelector;
+		QCalendarWidget *endDateSelector;
+		QPushButton *applyButton;
+};
+
+@ The pop up constructor is responsible for laying out the component widgets,
+setting the dates selected in each calendar to match the currently selected
+range, and connecting the appropriate signal handlers.
+
+@<CustomDateRangePopup implementation@>=
+CustomDateRangePopup::CustomDateRangePopup(QWidget *parent) :
+	QWidget(parent, Qt::Popup), startDateSelector(new QCalendarWidget),
+	endDateSelector(new QCalendarWidget), applyButton(new QPushButton(tr("Apply")))
+{
+	setAttribute(Qt::WA_WindowPropagation);
+
+	QVBoxLayout *outerLayout = new QVBoxLayout;
+	QHBoxLayout *calendarsLayout = new QHBoxLayout;
+	QVBoxLayout *startDateLayout = new QVBoxLayout;
+	QVBoxLayout *endDateLayout = new QVBoxLayout;
+	QHBoxLayout *buttonLayout = new QHBoxLayout;
+	QLabel *startDateLabel = new QLabel(tr("From"));
+	QLabel *endDateLabel = new QLabel(tr("To"));
+	startDateSelector->setVerticalHeaderFormat(QCalendarWidget::NoVerticalHeader);
+	endDateSelector->setVerticalHeaderFormat(QCalendarWidget::NoVerticalHeader);
+	DateRangeSelector *selector = qobject_cast<DateRangeSelector *>(parent);
+	if(parent) {
+		QStringList range = selector->currentRange().toStringList();
+		startDateSelector->setSelectedDate(QDate::fromString(range.first(), Qt::ISODate));
+		endDateSelector->setSelectedDate(QDate::fromString(range.last(), Qt::ISODate));
+	}
+	connect(startDateSelector, SIGNAL(selectionChanged()), this, SLOT(validateRange()));
+	connect(endDateSelector, SIGNAL(selectionChanged()), this, SLOT(validateRange()));
+
+	startDateLayout->addWidget(startDateLabel);
+	startDateLayout->addWidget(startDateSelector);
+	endDateLayout->addWidget(endDateLabel);
+	endDateLayout->addWidget(endDateSelector);
+
+	connect(applyButton, SIGNAL(clicked()), this, SLOT(applyRange()));
+
+	buttonLayout->addStretch();
+	buttonLayout->addWidget(applyButton);
+
+	calendarsLayout->addLayout(startDateLayout);
+	calendarsLayout->addLayout(endDateLayout);
+	outerLayout->addLayout(calendarsLayout);
+	outerLayout->addLayout(buttonLayout);
+	setLayout(outerLayout);
+}
+
+@ The pop up can be hidden in two ways. Clicking anywhere outside of the widget
+will hide the pop up. Clicking the Apply button will also hide the pop up. In
+the former case, we must inform the parent widget that it is fine to destroy
+the pop up widget, which we do by emitting a signal. Note that clicking outside
+of the widget will cause the |QHideEvent| to be posted automatically.
+
+@<CustomDateRangePopup implementation@>=
+void CustomDateRangePopup::hideEvent(QHideEvent *)
+{
+	emit hidingPopup();
+}
+
+@ Clicking the Apply button requires setting the Custom date range to the
+currently selected range and then hiding the pop up manually.
+
+@<CustomDateRangePopup implementation@>=
+void CustomDateRangePopup::applyRange()
+{
+	DateRangeSelector *selector = qobject_cast<DateRangeSelector *>(parentWidget());
+	if(selector)
+	{
+		selector->setCustomRange(QVariant(QStringList() <<
+			startDateSelector->selectedDate().toString(Qt::ISODate) <<
+			endDateSelector->selectedDate().toString(Qt::ISODate)));
+	}
+	hide();
+}
+
+@ The Apply button is enabled or disabled depending on if the currently
+selected dates form a valid range in which the end date does not occur before
+the start date.
+
+@<CustomDateRangePopup implementation@>=
+void CustomDateRangePopup::validateRange()
+{
+	if(startDateSelector->selectedDate() > endDateSelector->selectedDate())
+	{
+		applyButton->setEnabled(false);
+	}
+	else
+	{
+		applyButton->setEnabled(true);
+	}
+}
+
+@ The |DateRangeSelector| constructor is responsible for setting up the layout
+of the |QComboBox| and the |QToolButton|, adding appropriate items to the
+|QComboBox|, and connecting the signals required to handle the pop up
+correctly.
+
+@<DateRangeSelector implementation@>=
+DateRangeSelector::DateRangeSelector(QWidget *parent) :
+	QWidget(parent), quickSelector(new QComboBox(this)),
+	customRangeSelector(NULL), lastIndex(0)
+{
+	connect(quickSelector, SIGNAL(currentIndexChanged(int)), this, SLOT(updateRange(int)));
+
+	QDate currentDate = QDate::currentDate();
+
+	QHBoxLayout *layout = new QHBoxLayout;
+	@<Set common date ranges to quick selector@>@;
+	QToolButton *customButton = new QToolButton;
+	customButton->setIcon(QIcon::fromTheme("office-calendar",
+		QIcon(":/resources/icons/tango/scalable/apps/office-calendar.svg")));
+	layout->addWidget(quickSelector);
+	layout->addWidget(customButton);
+	setLayout(layout);
+
+	connect(customButton, SIGNAL(clicked()), this, SLOT(toggleCustom()));
+}
+
+@ The |QComboBox| provides a mechanism for associating additional data with an
+item. Several possible representations were considered, but what was ultimately
+selected was a |QVariant| containing a |QStringList| in which the first entry
+in the list is the starting date of the range and the last entry in the list is
+the ending date of the range. Note that the list may contain only one item in
+cases where the range only covers a single date, however one should not assume
+that a range covering a single date will only have a single list entry.
+
+@<Set common date ranges to quick selector@>=
+quickSelector->addItem("Yesterday", QVariant(QStringList() <<
+	currentDate.addDays(-1).toString(Qt::ISODate)));
+quickSelector->addItem("Today", QVariant(QStringList() <<
+	currentDate.toString(Qt::ISODate)));
+quickSelector->insertSeparator(quickSelector->count());
+quickSelector->addItem("This Week", QVariant(QStringList() <<
+	(currentDate.dayOfWeek() % 7 ?
+		currentDate.addDays(-currentDate.dayOfWeek()).toString(Qt::ISODate) :
+		currentDate.toString(Qt::ISODate)) <<
+			currentDate.addDays(6 - (currentDate.dayOfWeek() % 7)).toString(Qt::ISODate)));
+quickSelector->addItem("This Week to Date", currentDate.dayOfWeek() % 7 ?
+	QVariant(QStringList() <<
+	currentDate.addDays(-currentDate.dayOfWeek()).toString(Qt::ISODate) <<
+	currentDate.toString(Qt::ISODate)) :
+	QVariant(QStringList() << currentDate.toString(Qt::ISODate)));
+quickSelector->addItem("Last Week", QVariant(QStringList() <<
+	currentDate.addDays(-(currentDate.dayOfWeek() % 7) - 7).toString(Qt::ISODate) <<
+	currentDate.addDays(-(currentDate.dayOfWeek() % 7) - 1).toString(Qt::ISODate)));
+quickSelector->addItem("Last 7 Days", QVariant(QStringList() <<
+	currentDate.addDays(-6).toString(Qt::ISODate) <<
+	currentDate.toString(Qt::ISODate)));
+quickSelector->insertSeparator(quickSelector->count());
+quickSelector->addItem("This Month", QVariant(QStringList() <<
+	QDate(currentDate.year(), currentDate.month(), 1).toString(Qt::ISODate) <<
+	QDate(currentDate.year(), currentDate.month(),
+		currentDate.daysInMonth()).toString(Qt::ISODate)));
+quickSelector->addItem("This Month to Date", (currentDate.day() == 1 ?
+	(QVariant(QStringList() << currentDate.toString(Qt::ISODate))) :
+	(QVariant(QStringList() <<
+	QDate(currentDate.year(), currentDate.month(), 1).toString(Qt::ISODate) <<
+	currentDate.toString(Qt::ISODate)))));
+quickSelector->addItem("Last Four Weeks", QVariant(QStringList() <<
+	currentDate.addDays(-27).toString(Qt::ISODate) <<
+	currentDate.toString(Qt::ISODate)));
+quickSelector->addItem("Last 30 Days", QVariant(QStringList() <<
+	currentDate.addDays(-29).toString(Qt::ISODate) <<
+	currentDate.toString(Qt::ISODate)));
+quickSelector->insertSeparator(quickSelector->count());
+quickSelector->addItem("This Quarter", QVariant(QStringList() <<
+	QDate(currentDate.year(), currentDate.month() - ((currentDate.month() - 1) % 3), 1).toString(Qt::ISODate) <<
+	(currentDate.month() > 9 ?
+		QDate(currentDate.year(), 12, 31).toString(Qt::ISODate) :
+		QDate(currentDate.year(), currentDate.month() - ((currentDate.month() - 1) % 3) + 3, 1).addDays(-1).toString(Qt::ISODate))));
+quickSelector->addItem("This Quarter to Date",
+	(currentDate.day() == 1 && (currentDate.month() - 1) % 3 == 0) ?
+		QVariant(QStringList() << currentDate.toString(Qt::ISODate)) :
+		QVariant(QStringList() <<
+		QDate(currentDate.year(), currentDate.month() - ((currentDate.month() - 1) % 3), 1).toString(Qt::ISODate) <<
+		currentDate.toString(Qt::ISODate)));
+quickSelector->addItem("Last Quarter", currentDate.month() < 4 ?
+	QVariant(QStringList() <<
+		QDate(currentDate.year() - 1, 10, 1).toString(Qt::ISODate) <<
+		QDate(currentDate.year() - 1, 12, 31).toString(Qt::ISODate)) :
+	QVariant(QStringList() <<
+		QDate(currentDate.year(), currentDate.month() - ((currentDate.month() - 1) % 3) - 3, 1).toString(Qt::ISODate) <<
+		QDate(currentDate.year(), currentDate.month() - ((currentDate.month() - 1) % 3), 1).addDays(-1).toString(Qt::ISODate)));
+quickSelector->addItem("Last 90 Days", QVariant(QStringList() <<
+	currentDate.addDays(-89).toString(Qt::ISODate) <<
+	currentDate.toString(Qt::ISODate)));
+quickSelector->insertSeparator(quickSelector->count());
+quickSelector->addItem("This Year", QVariant(QStringList() <<
+	QDate(currentDate.year(), 1, 1).toString(Qt::ISODate) <<
+	QDate(currentDate.year(), 12, 31).toString(Qt::ISODate)));
+quickSelector->addItem("This Year to Date", (currentDate.dayOfYear() == 1) ?
+	QVariant(QStringList() << currentDate.toString(Qt::ISODate)) :
+	QVariant(QStringList() << QDate(currentDate.year(), 1, 1).toString(Qt::ISODate) <<
+	currentDate.toString(Qt::ISODate)));
+quickSelector->addItem("Last Year", QVariant(QStringList() <<
+	QDate(currentDate.year() - 1, 1, 1).toString(Qt::ISODate) <<
+	QDate(currentDate.year() - 1, 12, 31).toString(Qt::ISODate)));
+quickSelector->addItem("Last 365 Days", QVariant(QStringList() <<
+	currentDate.addDays(-364).toString(Qt::ISODate) <<
+	currentDate.toString(Qt::ISODate)));
+quickSelector->insertSeparator(quickSelector->count());
+quickSelector->addItem("Custom");
+
+@ Special handling of the Custom range is required because it is possible to
+select this from the |QComboBox| and then not set a range. This should result
+in the selection changing back to the most recent valid selection. Creating the
+pop up in this way is handled in |updateRange()|.
+
+@<DateRangeSelector implementation@>=
+void DateRangeSelector::updateRange(int index)
+{
+	if(index != lastIndex && index == quickSelector->count() - 1)
+	{
+		toggleCustom();
+	}
+	else
+	{
+		lastIndex = index;
+		emit rangeUpdated(quickSelector->itemData(quickSelector->currentIndex()));
+	}
+}
+
+@ Resetting the range to the most recent valid selection is handled in
+|popupHidden()|.
+
+@<DateRangeSelector implementation@>=
+void DateRangeSelector::popupHidden()
+{
+	customRangeSelector->deleteLater();
+	customRangeSelector = NULL;
+	quickSelector->setCurrentIndex(lastIndex);
+}
+
+@ If Custom is set to a new valid range, |lastIndex| will have been set to
+point to the appropriate item by a call to |setCustomRange()|.
+
+@<DateRangeSelector implementation@>=
+void DateRangeSelector::setCustomRange(QVariant range)
+{
+	quickSelector->setItemData(quickSelector->count() - 1, range);
+	emit rangeUpdated(range);
+	lastIndex = quickSelector->count() - 1;
+	quickSelector->setCurrentIndex(lastIndex);
+}
+
+@ When creating the pop up, it should ideally be placed such that the left of
+the pop up is aligned with the left of the widget that is normally shown and
+immediately under it, however if this would result in part of the pop up not
+fitting on the same screen, it should be moved to make a best effort at full
+visibility.
+
+@<DateRangeSelector implementation@>=
+void DateRangeSelector::toggleCustom()
+{
+	if(!customRangeSelector) {
+		customRangeSelector = new CustomDateRangePopup(this);
+		QPoint pos = rect().bottomLeft();
+		QPoint pos2 = rect().topLeft();
+		pos = mapToGlobal(pos);
+		pos2 = mapToGlobal(pos2);
+		QSize size = customRangeSelector->sizeHint();
+		QRect screen = QApplication::desktop()->availableGeometry(pos);
+		if(pos.x()+size.width() > screen.right()) {
+			pos.setX(screen.right()-size.width());
+		}
+		pos.setX(qMax(pos.x(), screen.left()));
+		if(pos.y() + size.height() > screen.bottom()) {
+			pos.setY(pos2.y() - size.height());
+		} else if (pos.y() < screen.top()){
+			pos.setY(screen.top());
+		}
+		if(pos.y() < screen.top()) {
+			pos.setY(screen.top());
+		}
+		if(pos.y()+size.height() > screen.bottom()) {
+			pos.setY(screen.bottom()-size.height());
+		}
+		customRangeSelector->move(pos);
+		customRangeSelector->show();
+		connect(customRangeSelector, SIGNAL(hidingPopup()),
+				this, SLOT(popupHidden()));
+    }
+	else
+	{
+		customRangeSelector->close();
+		customRangeSelector->deleteLater();
+		customRangeSelector = NULL;
+	}
+}
+
+@ While a signal is emitted when the selected range changes, it is frequently
+convenient to have a way to request the currently selected range at any time.
+
+@<DateRangeSelector implementation@>=
+QVariant DateRangeSelector::currentRange()
+{
+	return quickSelector->itemData(lastIndex);
+}
+
+@ To use this new control in Typica, we should provide a way to create it from
+the XML description of a window.
+
+@<Additional box layout elements@>=
+else if(currentElement.tagName() == "daterange")
+{
+	addDateRangeToLayout(currentElement, widgetStack, layoutStack);
+}
+
+@ The method for adding a date range selector to a layout is currently trivial.
+Additional features may be added to this in the future to provide better
+support for specifying an initial default selection. At present the only
+supported attribute is the |"id"| attribute which is used to make the widget
+accessible to scripts.
+
+@<Functions for scripting@>=
+void addDateRangeToLayout(QDomElement element, QStack<QWidget *> *,@|
+                          QStack<QLayout *> *layoutStack)
+{
+	DateRangeSelector *widget = new DateRangeSelector;
+	if(element.hasAttribute("id"))
+	{
+		widget->setObjectName(element.attribute("id"));
+	}
+	QBoxLayout *layout = qobject_cast<QBoxLayout *>(layoutStack->top());
+	layout->addWidget(widget);
+}
+
+@ The prototype needs to be specified.
+
+@<Function prototypes for scripting@>=
+void addDateRangeToLayout(QDomElement element,
+                          QStack<QWidget *> *widgetStack,
+                          QStack<QLayout *> *layoutStack);
+
+@ Our header is also required.
+
+@<Header files to include@>=
+#include "daterangeselector.h"

src/resources.qrc

         <file>resources/icons/tango/22x22/categories/applications-graphics.png</file>
         <file>resources/icons/tango/32x32/categories/applications-graphics.png</file>
         <file>resources/icons/tango/scalable/categories/applications-graphics.svg</file>
+        <file>resources/icons/tango/16x16/apps/office-calendar.png</file>
+        <file>resources/icons/tango/22x22/apps/office-calendar.png</file>
+        <file>resources/icons/tango/32x32/apps/office-calendar.png</file>
+        <file>resources/icons/tango/scalable/apps/office-calendar.svg</file>
     </qresource>
 </RCC>

src/typica.w

 				QBoxLayout *layout = qobject_cast<QBoxLayout *>(layoutStack->top());
 				layout->addStretch();
 			}
+			@<Additional box layout elements@>@;
 		}
 	}
 }
 	value.setProperty("print", engine->newFunction(QTextEdit_print));
 }
 
+@i daterangeselector.w
+
 @** An area for repeated user interface elements.
 
 \noindent There are multiple use cases in which it is useful to specify a