Added component button drag and drop to add component at a position in the scene

Author: BenPyton

SoundGenerator.pro

@@ -55,7 +55,8 @@ SOURCES += \
 	UI/pinoutputitem.cpp \
 	UI/pininputitem.cpp \
     wavformat.cpp \
-    UI/lineeditqreal.cpp
+    UI/lineeditqreal.cpp \
+    UI/pushordragbutton.cpp
 
 HEADERS += \
         Components/AddComponent.h \
@@ -86,7 +87,8 @@ HEADERS += \
 	UI/pinoutputitem.h \
 	UI/pininputitem.h \
     wavformat.h \
-    UI/lineeditqreal.h
+    UI/lineeditqreal.h \
+    UI/pushordragbutton.h
 
 FORMS += \
         UI/mainwindow.ui

UI/mainwindow.cpp

@@ -26,6 +26,7 @@
 #include "waveformview.h"
 #include "pininputitem.h"
 #include "lineeditqreal.h"
+#include "pushordragbutton.h"
 #include <QStyle>
 #include <utils.h>
 
@@ -97,7 +98,7 @@ MainWindow::MainWindow(QWidget *parent) :
         QAction* action = new QAction(component, this);
         connect(action, &QAction::triggered, [this, component]() { ui->nodalView->createComponent(component); });
 
-        QPushButton* button = new QPushButton(component);
+        PushOrDragButton* button = new PushOrDragButton(component);
         button->setProperty("class", "component");
         ui->buttonLayout->addWidget(button);
         connect(button, SIGNAL(clicked()), action, SLOT(trigger()));
@@ -373,7 +374,6 @@ void MainWindow::about()
 
     box.setTextFormat(Qt::RichText);
     box.exec();
-
 }
 
 void MainWindow::exportWAV()

UI/nodalview.cpp

@@ -326,15 +326,32 @@ void NodalView::mouseMoveEvent(QMouseEvent* event)
 
 void NodalView::dragEnterEvent(QDragEnterEvent *event)
 {
-    Q_UNUSED(event);
+    if(event->mimeData()->hasFormat("add/component"))
+    {
+        event->acceptProposedAction();
+    }
 }
 
 void NodalView::dropEvent(QDropEvent *event)
+{
+    event->acceptProposedAction();
+
+    QString componentName = QString::fromUtf8(event->mimeData()->data("add/component"));
+
+    m_nextCreationPosition = mapToScene(event->pos());
+    createNode(componentName);
+}
+
+// must be implemented
+void NodalView::dragMoveEvent(QDragMoveEvent *event)
 {
     Q_UNUSED(event);
-    //m_nextCreationPosition = mapToScene(event->pos());
+}
 
-    //const QMimeData* data = event->mimeData();
+// must be implemented
+void NodalView::dragLeaveEvent(QDragLeaveEvent *event)
+{
+    Q_UNUSED(event);
 }
 
 void NodalView::drawBackground(QPainter *painter, const QRectF &rect)

UI/nodalview.h

@@ -59,6 +59,8 @@ class NodalView : public QGraphicsView
     virtual void mouseReleaseEvent(QMouseEvent *event) override;
     virtual void mouseMoveEvent(QMouseEvent* event) override;
     virtual void dragEnterEvent(QDragEnterEvent* event) override;
+    virtual void dragMoveEvent(QDragMoveEvent* event) override;
+    virtual void dragLeaveEvent(QDragLeaveEvent* event) override;
     virtual void dropEvent(QDropEvent* event) override;
 
     virtual void drawBackground(QPainter * painter, const QRectF & rect) override;

UI/pushordragbutton.cpp

@@ -0,0 +1,50 @@
+#include "pushordragbutton.h"
+#include <QApplication>
+#include <QDrag>
+#include <QMimeData>
+#include <qevent.h>
+#include <QtCore>
+
+PushOrDragButton::PushOrDragButton(QWidget *parent)
+    : QPushButton(parent)
+{ }
+
+PushOrDragButton::PushOrDragButton(const QString &text, QWidget *parent)
+    : QPushButton(text, parent)
+{ }
+
+PushOrDragButton::PushOrDragButton(const QIcon &icon, const QString &text, QWidget *parent)
+    : QPushButton(icon, text, parent)
+{ }
+
+void PushOrDragButton::mousePressEvent(QMouseEvent *event)
+{
+    QPushButton::mousePressEvent(event);
+
+    if (event->button() == Qt::LeftButton)
+        m_dragStartPosition = event->pos();
+    qDebug() << "click";
+}
+
+void PushOrDragButton::mouseMoveEvent(QMouseEvent *event)
+{
+    QPushButton::mouseMoveEvent(event);
+
+    if (!(event->buttons() & Qt::LeftButton))
+            return;
+    if ((event->pos() - m_dragStartPosition).manhattanLength()
+         < QApplication::startDragDistance())
+        return;
+
+    qDebug() << "drag";
+
+    QDrag *drag = new QDrag(this);
+    QMimeData *mimeData = new QMimeData();
+
+    mimeData->setData("add/component", text().toUtf8());
+    drag->setMimeData(mimeData);
+
+    drag->exec(Qt::MoveAction);
+
+    setDown(false);
+}

UI/pushordragbutton.h

@@ -0,0 +1,21 @@
+#ifndef PUSHORDRAGBUTTON_H
+#define PUSHORDRAGBUTTON_H
+
+#include <QPushButton>
+
+class PushOrDragButton : public QPushButton
+{
+public:
+    PushOrDragButton(QWidget *parent = nullptr);
+    PushOrDragButton(const QString &text, QWidget *parent = nullptr);
+    PushOrDragButton(const QIcon &icon, const QString &text, QWidget *parent = nullptr);
+
+protected:
+    virtual void mousePressEvent(QMouseEvent* event) override;
+    virtual void mouseMoveEvent(QMouseEvent* event) override;
+
+private:
+    QPointF m_dragStartPosition;
+};
+
+#endif // PUSHORDRAGBUTTON_H