ui: Added more movement controls to the graph

* SHIFT + mouse wheel for zooming
* WASD for moving up, right, left, down
* SHIFT + WS for zooming
* zoom anchor is under the mouse

bug id = 54

src/lib_gui/qt/graphics/QtGraphicsView.cpp

@@ -0,0 +1,139 @@
+#include "qt/graphics/QtGraphicsView.h"
+
+#include <QPropertyAnimation>
+#include <QScrollBar>
+#include <QMouseEvent>
+
+QtGraphicsView::QtGraphicsView(QWidget* parent)
+	: QGraphicsView(parent)
+	, m_zoomFactor(1.0f)
+	, m_appZoomFactor(1.0f)
+{
+	setTransformationAnchor(QGraphicsView::AnchorUnderMouse);
+}
+
+float QtGraphicsView::getZoomFactor() const
+{
+	return m_appZoomFactor;
+}
+
+void QtGraphicsView::setAppZoomFactor(float appZoomFactor)
+{
+	m_appZoomFactor = appZoomFactor;
+	updateTransform();
+}
+
+qreal QtGraphicsView::zoom() const
+{
+	return m_zoomFactor;
+}
+
+void QtGraphicsView::setZoom(qreal zoom)
+{
+	m_zoomFactor = zoom;
+	updateTransform();
+}
+
+void QtGraphicsView::mousePressEvent(QMouseEvent *event)
+{
+	if (event->button() == Qt::LeftButton && !itemAt(event->pos()))
+	{
+		m_last = event->pos();
+	}
+
+	QGraphicsView::mousePressEvent(event);
+}
+
+void QtGraphicsView::mouseReleaseEvent(QMouseEvent *event)
+{
+	if (event->button() == Qt::LeftButton && !itemAt(event->pos()) && event->pos() == m_last)
+	{
+		emit emptySpaceClicked();
+	}
+
+	QGraphicsView::mouseReleaseEvent(event);
+	viewport()->setCursor(Qt::ArrowCursor);
+}
+
+void QtGraphicsView::keyPressEvent(QKeyEvent* event)
+{
+	float delta = 150;
+	float x = 0.0f;
+	float y = 0.0f;
+
+	if (event->key() == Qt::Key_W)
+	{
+		if (event->modifiers() == Qt::ShiftModifier)
+		{
+			updateZoom(true);
+			return;
+		}
+
+		y -= delta;
+	}
+	else if (event->key() == Qt::Key_A)
+	{
+		x -= delta;
+	}
+	else if (event->key() == Qt::Key_S)
+	{
+		if (event->modifiers() == Qt::ShiftModifier)
+		{
+			updateZoom(false);
+			return;
+		}
+
+		y += delta;
+	}
+	else if (event->key() == Qt::Key_D)
+	{
+		x += delta;
+	}
+	else
+	{
+		return;
+	}
+
+	if (x != 0)
+	{
+		QPropertyAnimation* anim = new QPropertyAnimation(horizontalScrollBar(), "value");
+		anim->setDuration(100);
+		anim->setStartValue(horizontalScrollBar()->value());
+		anim->setEndValue(horizontalScrollBar()->value() + x);
+		anim->start();
+	}
+	if (y != 0)
+	{
+		QPropertyAnimation* anim = new QPropertyAnimation(verticalScrollBar(), "value");
+		anim->setDuration(100);
+		anim->setStartValue(verticalScrollBar()->value());
+		anim->setEndValue(verticalScrollBar()->value() + y);
+		anim->start();
+	}
+}
+
+void QtGraphicsView::wheelEvent(QWheelEvent* event)
+{
+	if (event->modifiers() == Qt::ShiftModifier && event->delta() != 0.0f)
+	{
+		updateZoom(event->delta() > 0.0f);
+		return;
+	}
+
+	QGraphicsView::wheelEvent(event);
+}
+
+void QtGraphicsView::updateTransform()
+{
+	float zoomFactor = m_appZoomFactor * m_zoomFactor;
+	setTransform(QTransform(zoomFactor, 0, 0, zoomFactor, 0, 0));
+}
+
+void QtGraphicsView::updateZoom(bool in)
+{
+	QPropertyAnimation* anim = new QPropertyAnimation(this, "zoom");
+	anim->setDuration(100);
+	anim->setStartValue(m_zoomFactor);
+	anim->setEndValue(m_zoomFactor * (1.0f + 0.3 * (in ? 1 : -1)));
+	anim->start();
+}