Refactor d&d code out into a separate class

src/qt/meson.build

@@ -35,6 +35,7 @@ executable(app_name,
 	project_config_file,
 	gitrev_config_file,
 	'widgets/block_grid.cpp',
+	'widgets/detail/block_drag_and_drop.cpp',
 	'make_qt_animation.cpp',
 	'animated_pixmap.cpp',
 	include_directories: inc,

src/qt/widgets/block_grid.cpp

@@ -21,11 +21,6 @@
 #include <QTimer>
 #include <QPixmap>
 #include <QPoint>
-#include <QByteArray>
-#include <QDataStream>
-#include <QMouseEvent>
-#include <QMimeData>
-#include <QDrag>
 #include <algorithm>
 
 namespace duck::widget {
@@ -48,8 +43,14 @@ namespace {
 
 BlockGrid::BlockGrid (QWidget* parent, unsigned int rows, unsigned int columns, float fps) :
 	QWidget(parent),
-	m_anim_timer(new QTimer(this)),
+	m_block_dnd(
+		this,
+		{[this](QPoint pt){return locate_icon_index_at(pt);}},
+		{[this](){return m_icons.size();}},
+		{[this](std::size_t index)->const QPixmap&{return m_icons[index].current_frame();}}
+	),
 	m_icon_size(-1, -1),
+	m_anim_timer(new QTimer(this)),
 	m_rows(rows),
 	m_columns(columns)
 {
@@ -126,34 +127,7 @@ void BlockGrid::paintEvent (QPaintEvent* event) {
 }
 
 void BlockGrid::mousePressEvent(QMouseEvent* event) {
-	const auto [icon_index, block_origin]  = locate_icon_index_at(event->position().toPoint());
-	if (icon_index < 0)
-		return;
-
-	const auto icon_index_uns = static_cast<std::size_t>(icon_index);
-	if (icon_index_uns >= m_icons.size())
-		return;
-
-	QByteArray item_data;
-	QDataStream data_stream(&item_data, QIODevice::WriteOnly);
-	data_stream << m_icons[icon_index_uns].current_frame();
-
-	std::unique_ptr<QMimeData> mime_data(new QMimeData);
-	mime_data->setData("application/x-dndblock", item_data);
-
-	QDrag* const drag(new QDrag(this));
-	drag->setMimeData(mime_data.release());
-	drag->setPixmap(m_icons[icon_index_uns].current_frame());
-	drag->setHotSpot(event->position().toPoint() - block_origin);
-
-	switch (drag->exec(Qt::CopyAction | Qt::MoveAction, Qt::CopyAction)) {
-	case Qt::MoveAction:
-		break;
-	case Qt::CopyAction:
-		break;
-	default:
-		break;
-	}
+	m_block_dnd.mouse_press_event(event);
 }
 
 void BlockGrid::advance_frame() {

src/qt/widgets/block_grid.hpp

@@ -18,6 +18,7 @@
 #pragma once
 
 #include "../animated_pixmap.hpp"
+#include "detail/block_drag_and_drop.hpp"
 #include <QWidget>
 #include <QPixmap>
 #include <memory>
@@ -55,10 +56,11 @@ private:
 	unsigned int columns() const;
 	std::pair<int, QPoint> locate_icon_index_at (QPoint pt) const;
 
+	detail::BlockDragAndDrop m_block_dnd;
 	std::vector<AnimatedPixmap> m_icons;
+	QSize m_icon_size;
 	QTimer* m_anim_timer;
 	std::unique_ptr<QPixmap> m_empty_icon;
-	QSize m_icon_size;
 	unsigned int m_rows;
 	unsigned int m_columns;
 };

src/qt/widgets/detail/block_drag_and_drop.cpp

@@ -0,0 +1,77 @@
+/* Copyright 2020-2025, Michele Santullo
+ * This file is part of memoserv.
+ *
+ * Memoserv is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Memoserv is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Memoserv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "block_drag_and_drop.hpp"
+#include <QByteArray>
+#include <QDataStream>
+#include <QMouseEvent>
+#include <QMimeData>
+#include <QDrag>
+#include <QApplication>
+#include <cassert>
+#include <ciso646>
+#include <memory>
+
+namespace duck::widget::detail {
+namespace {
+constexpr char g_drag_mime[] = "application/x-dndblock";
+} //unnamed namespace
+
+BlockDragAndDrop::BlockDragAndDrop (
+	QObject* parent,
+	PointToIndexFunc&& func,
+	std::function<std::size_t()>&& get_block_count,
+	std::function<const QPixmap&(std::size_t)>&& get_pixmap
+) :
+	m_point_to_index(std::move(func)),
+	m_get_block_count(std::move(get_block_count)),
+	m_get_pixmap(std::move(get_pixmap)),
+	m_parent(parent)
+{
+	assert(m_parent);
+}
+
+void BlockDragAndDrop::mouse_press_event (const QMouseEvent* event) {
+	const auto [icon_index, block_origin]  = m_point_to_index(event->position().toPoint());
+	if (icon_index < 0)
+		return;
+	const auto icon_index_uns = static_cast<std::size_t>(icon_index);
+	if (icon_index_uns >= m_get_block_count())
+		return;
+
+	QByteArray item_data;
+	QDataStream data_stream(&item_data, QIODevice::WriteOnly);
+	data_stream << m_get_pixmap(icon_index_uns);
+
+	std::unique_ptr<QMimeData> mime_data(new QMimeData);
+	mime_data->setData(g_drag_mime, item_data);
+
+	QDrag* const drag(new QDrag(m_parent));
+	drag->setMimeData(mime_data.release());
+	drag->setPixmap(m_get_pixmap(icon_index_uns));
+	drag->setHotSpot(event->position().toPoint() - block_origin);
+
+	switch (drag->exec(Qt::CopyAction | Qt::MoveAction, Qt::CopyAction)) {
+	case Qt::MoveAction:
+		break;
+	case Qt::CopyAction:
+		break;
+	default:
+		break;
+	}
+}
+} //namespace duck::widget::detail

src/qt/widgets/detail/block_drag_and_drop.hpp

@@ -0,0 +1,48 @@
+/* Copyright 2020-2025, Michele Santullo
+ * This file is part of memoserv.
+ *
+ * Memoserv is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Memoserv is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Memoserv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <QPoint>
+#include <functional>
+#include <utility>
+
+class QMouseEvent;
+class QPixmap;
+
+namespace duck::widget::detail {
+class BlockDragAndDrop {
+public:
+	typedef std::function<std::pair<int,QPoint>(QPoint)> PointToIndexFunc;
+
+	BlockDragAndDrop (
+		QObject* parent,
+		PointToIndexFunc&& func,
+		std::function<std::size_t()>&& get_block_count,
+		std::function<const QPixmap&(std::size_t)>&& get_pixmap
+	);
+
+	void mouse_press_event (const QMouseEvent* event);
+
+private:
+	PointToIndexFunc m_point_to_index;
+	std::function<std::size_t()> m_get_block_count;
+	std::function<const QPixmap&(std::size_t)> m_get_pixmap;
+	QObject* m_parent;
+};
+
+} //namespace duck::widget::detail