introduce WidgetMoverButton (to realize the "move layer" feature in the...

introduce WidgetMoverButton (to realize the "move layer" feature in the upcoming layer oriented sample editor)

GUI/Views/SampleDesigner/WidgetMoverButton.cpp

+//  ************************************************************************************************
+//
+//  BornAgain: simulate and fit reflection and scattering
+//
+//! @file      GUI/Views/SampleDesigner/WidgetMoverButton.cpp
+//! @brief     Implements class WidgetMoverButton
+//!
+//! @homepage  http://www.bornagainproject.org
+//! @license   GNU General Public License v3 or higher (see COPYING)
+//! @copyright Forschungszentrum Jülich GmbH 2021
+//! @authors   Scientific Computing Group at MLZ (see CITATION, AUTHORS)
+//
+//  ************************************************************************************************
+
+#include "GUI/Views/SampleDesigner/WidgetMoverButton.h"
+#include <QLayout>
+#include <QMouseEvent>
+#include <QPropertyAnimation>
+
+WidgetMoverButton::WidgetMoverButton(QWidget* parent, QWidget* widgetToMove, int ignoreOnTop)
+    : QToolButton(parent), m_widgetToMove(widgetToMove), m_ignoreOnTop(ignoreOnTop)
+{
+    setIcon(QIcon(":/images/toolbar24dark_hambar.svg"));
+}
+
+void WidgetMoverButton::mousePressEvent(QMouseEvent* event)
+{
+    m_mouseDownY = event->globalY();
+}
+
+void WidgetMoverButton::mouseReleaseEvent(QMouseEvent* event)
+{
+    m_started = false;
+    if (m_layoutToDeactivate != nullptr) {
+        m_layoutToDeactivate->setEnabled(true);
+        m_layoutToDeactivate->update();
+    }
+    emit finishedMoving(m_widgetToMove, m_dropAboveThisWidget);
+}
+
+void WidgetMoverButton::mouseMoveEvent(QMouseEvent* event)
+{
+    int dy = event->globalY() - m_mouseDownY;
+    if (abs(dy) > 5 && !m_started) {
+        m_started = true;
+
+        m_layoutToDeactivate = m_widgetToMove->parentWidget()->layout();
+
+        m_yOfFirstRelevantWidget = m_layoutToDeactivate->itemAt(m_ignoreOnTop)->geometry().top();
+        m_layoutToDeactivate->setEnabled(false);
+        m_originalWidgetY = m_widgetToMove->y();
+        m_widgetToMove->raise();
+        emit startingToMove();
+        m_widgetToMove->move(m_widgetToMove->x() + 5, m_widgetToMove->y());
+        m_widgetToMove->resize(m_widgetToMove->width() - 10, m_widgetToMove->height());
+    }
+
+    if (m_started) {
+
+        // -- move the dragged widget to the new position
+        m_widgetToMove->move(m_widgetToMove->x(), m_originalWidgetY + dy);
+
+        // -- move other widgets to make room
+        m_dropAboveThisWidget = nullptr;
+        int yTopOfLayoutItem = m_yOfFirstRelevantWidget;
+
+        for (int i = m_ignoreOnTop; i < m_layoutToDeactivate->count(); ++i) {
+            auto* layoutItem = m_layoutToDeactivate->itemAt(i);
+            if (layoutItem->widget() == m_widgetToMove)
+                continue;
+
+            const bool movedWidgetIsAboveThisLayoutItem =
+                m_widgetToMove->y() < yTopOfLayoutItem + layoutItem->geometry().height() / 2;
+            if (movedWidgetIsAboveThisLayoutItem && layoutItem->widget() != nullptr
+                && m_dropAboveThisWidget == nullptr)
+                m_dropAboveThisWidget = layoutItem->widget();
+
+            QRect r = layoutItem->geometry();
+            if (movedWidgetIsAboveThisLayoutItem)
+                r.moveTop(yTopOfLayoutItem + m_widgetToMove->height()
+                          + m_layoutToDeactivate->spacing());
+            else
+                r.moveTop(yTopOfLayoutItem);
+
+            if (r != layoutItem->geometry()) {
+                QWidget* w = layoutItem->widget();
+                if (w == nullptr) {
+                    layoutItem->setGeometry(r);
+                } else {
+                    QPropertyAnimation* animation = new QPropertyAnimation(w, "geometry");
+                    animation->setDuration(100);
+                    animation->setEasingCurve(QEasingCurve::OutQuad);
+                    animation->setStartValue(w->geometry());
+                    animation->setEndValue(r);
+
+                    animation->start();
+                }
+            }
+
+            yTopOfLayoutItem += r.height() + m_layoutToDeactivate->spacing();
+        }
+    }
+}

GUI/Views/SampleDesigner/WidgetMoverButton.h

+//  ************************************************************************************************
+//
+//  BornAgain: simulate and fit reflection and scattering
+//
+//! @file      GUI/Views/SampleDesigner/WidgetMoverButton.h
+//! @brief     Defines class WidgetMoverButton
+//!
+//! @homepage  http://www.bornagainproject.org
+//! @license   GNU General Public License v3 or higher (see COPYING)
+//! @copyright Forschungszentrum Jülich GmbH 2021
+//! @authors   Scientific Computing Group at MLZ (see CITATION, AUTHORS)
+//
+//  ************************************************************************************************
+
+#ifndef BORNAGAIN_GUI_VIEWS_SAMPLEDESIGNER_WIDGETMOVERBUTTON_H
+#define BORNAGAIN_GUI_VIEWS_SAMPLEDESIGNER_WIDGETMOVERBUTTON_H
+
+#include <QToolButton>
+
+//! Button to move a widget vertically in a layout.
+//!
+//! With this button, the "move layer" feature in the layer oriented sample editor is realized
+//! (it is the button on each LayerForm).
+//!
+//! When pressing the button, the parent layout of the widget is deactivated, and the widget is
+//! moved to the position where the pressed mouse cursor is moved.
+//! When the mouse is released, the layout is again activated and a signal finishedMoving() is
+//! emitted. Any reordering of the widgets in the layout then has to be handled outside - no
+//! reordering is done in here.
+class WidgetMoverButton : public QToolButton {
+    Q_OBJECT
+public:
+    //! Create a widget mover button.
+    //!
+    //! If the widget shall not be able to be dragged on the top position, this can be defined by
+    //! ignoreOnTop (the number of widgets at the top of the layout which shall not be affected by
+    //! the reordering). In the case of the layer moving, the topmost Form (the multilayer
+    //! properties) shall not be part of reordering.
+    WidgetMoverButton(QWidget* parent, QWidget* widgetToMove, int ignoreOnTop = 0);
+
+protected:
+    virtual void mousePressEvent(QMouseEvent* event) override;
+    virtual void mouseReleaseEvent(QMouseEvent* event) override;
+    virtual void mouseMoveEvent(QMouseEvent* event) override;
+
+signals:
+    void startingToMove();
+    void finishedMoving(QWidget* widgetToMove, QWidget* moveAboveThisWidget);
+
+private:
+    bool m_started = false;
+    int m_mouseDownY;
+    QLayout* m_layoutToDeactivate = nullptr;
+    QWidget* m_widgetToMove;
+    QWidget* m_dropAboveThisWidget;
+    int m_originalWidgetY;
+    int m_yOfFirstRelevantWidget;
+    int m_ignoreOnTop;
+};
+
+
+#endif // BORNAGAIN_GUI_VIEWS_SAMPLEDESIGNER_WIDGETMOVERBUTTON_H