Draggable label

src/scales.w

@@ -0,0 +1,58 @@
+@** Collecting Measurements from Scales.
+
+\noindent When a computer connected scale is available, it can be useful to
+eliminate manual transcription from the data entry for batches. In general it
+is difficult to determine where a measurement should go automatically, but
+there are a number of situations where the ability to drag a measurement from a
+label and drop it to whatever input widget is appropriate would be a useful
+operation to support.
+
+To support this, we need to subclass |QLabel| to allow it to initiate a drag
+and drop operation.
+
+@(draglabel.h@>=
+#ifndef TypicaDragLabelInclude
+#define TypicaDragLabelInclude
+
+#include <QLabel>
+
+class DragLabel : public QLabel
+{
+	Q_OBJECT
+	public:
+		explicit DragLabel(const QString &labelText, QWidget *parent = NULL);
+	protected:
+		void mousePressEvent(QMouseEvent *event);
+};
+
+#endif
+
+@ The font size of the label is increased by default to make it easier to
+manipulate on a touch screen. Otherwise, there is little to do in this class.
+
+@(draglabel.cpp@>=
+#include "draglabel.h"
+
+#include <QDrag>
+#include <QMouseEvent>
+
+DragLabel::DragLabel(const QString &labelText, QWidget *parent) :
+	QLabel(labelText, parent)
+{
+	QFont labelFont = font();
+	labelFont.setPointSize(14);
+	setFont(labelFont);
+}
+
+void DragLabel::mousePressEvent(QMouseEvent *event)
+{
+	if(event->button() == Qt::LeftButton)
+	{
+		QDrag *drag = new QDrag(this);
+		QMimeData *mimeData = new QMimeData;
+		mimeData->setText(text());
+		drag->setMimeData(mimeData);
+		drag->exec();
+	}
+}
+