HotcueButton: move drag info and dnd verification to separate file

CMakeLists.txt

@@ -1510,6 +1510,7 @@ add_library(
   src/widget/findonwebmenuservices/findonwebmenulastfm.cpp
   src/widget/findonwebmenuservices/findonwebmenusoundcloud.cpp
   src/widget/hexspinbox.cpp
+  src/widget/hotcuedrag.cpp
   src/widget/paintable.cpp
   src/widget/wanalysislibrarytableview.cpp
   src/widget/wbasewidget.cpp

src/skin/legacy/legacyskinparser.cpp

@@ -1917,7 +1917,7 @@ QString LegacySkinParser::getSharedGroupString(const QString& channelStr) {
 
 QWidget* LegacySkinParser::parseHotcueButton(const QDomElement& element) {
     QString group = lookupNodeGroup(element);
-    WHotcueButton* pWidget = new WHotcueButton(group, m_pParent);
+    WHotcueButton* pWidget = new WHotcueButton(m_pParent, group);
     commonWidgetSetup(element, pWidget);
     pWidget->setup(element, *m_pContext);
     pWidget->installEventFilter(m_pKeyboard);

src/widget/hotcuedrag.cpp

@@ -0,0 +1,60 @@
+#include <widget/hotcuedrag.h>
+
+#include <QDragEnterEvent>
+#include <QMimeData>
+#include <QMouseEvent>
+#include <QString>
+
+#include "mixer/playerinfo.h"
+#include "track/track.h"
+
+namespace mixxx {
+
+namespace hotcuedrag {
+
+/// Check if the event is a valid hotcue drag or drop event.
+/// Event must be a QDragEnterEvent or a QDropEvent.
+/// In case of QDropEvent, the HotcueDragInfo is extracted and the pointer
+/// data is used by the caller (WHotcueButton) to swap hotuces.
+template<typename T>
+bool isValidHotcueDragOrDropEvent(T* pEvent,
+        QObject* pTarget,
+        const QString& group,
+        int ignoreHotcueIndex,
+        HotcueDragInfo* pDragData) {
+    bool isDrag = std::same_as<QDragEnterEvent, T>;
+    // Allow source == target in the drag case so we get the drag cursor
+    // (i.e. not the 'drop rejected' cursor) when starting the drag and when
+    // dragging over the source later on.
+    // Same exception for hotcue index check below.
+    if (!isDrag && pEvent->source() == pTarget) {
+        return false;
+    }
+    TrackPointer pTrack = PlayerInfo::instance().getTrackInfo(group);
+    if (!pTrack) {
+        return false;
+    }
+    const QByteArray mimeDataBytes = pEvent->mimeData()->data(kDragDataType);
+    if (mimeDataBytes.isEmpty()) {
+        return false;
+    }
+    const HotcueDragInfo dragData = HotcueDragInfo::fromByteArray(mimeDataBytes);
+    if (dragData.isValid() &&
+            (isDrag || dragData.hotcue != ignoreHotcueIndex) &&
+            dragData.trackId == pTrack->getId()) {
+        if (pDragData != nullptr) {
+            *pDragData = dragData;
+        }
+        return true;
+    }
+    return false;
+};
+
+} // namespace hotcuedrag
+
+} // namespace mixxx
+
+template bool mixxx::hotcuedrag::isValidHotcueDragOrDropEvent<QDropEvent>(
+        QDropEvent*, QObject*, const QString&, int, HotcueDragInfo*);
+template bool mixxx::hotcuedrag::isValidHotcueDragOrDropEvent<QDragEnterEvent>(
+        QDragEnterEvent*, QObject*, const QString&, int, HotcueDragInfo*);

src/widget/hotcuedrag.h

@@ -0,0 +1,60 @@
+#pragma once
+
+#include <QBuffer>
+#include <QMimeData>
+#include <QString>
+
+#include "track/cue.h"
+#include "track/trackid.h"
+
+const QString kDragDataType = QStringLiteral("hotcueDragInfo");
+
+class TrackId;
+
+struct HotcueDragInfo {
+    HotcueDragInfo() {};
+    HotcueDragInfo(TrackId id, int cue)
+            : trackId(id),
+              hotcue(cue) {};
+
+    static HotcueDragInfo fromByteArray(const QByteArray& bytes) {
+        QDataStream stream(bytes);
+        TrackId trackId;
+        int hotcue;
+        stream >> trackId >> hotcue;
+        return HotcueDragInfo(trackId, hotcue);
+    };
+
+    QByteArray toByteArray() {
+        QByteArray bytes;
+        QDataStream dataStream(&bytes, QIODevice::WriteOnly);
+        dataStream << trackId << hotcue;
+        return bytes;
+    };
+
+    bool isValid() const {
+        return trackId.isValid() && hotcue != Cue::kNoHotCue;
+    }
+
+    TrackId trackId = TrackId();
+    int hotcue = Cue::kNoHotCue;
+};
+
+namespace mixxx {
+
+namespace hotcuedrag {
+
+/// Check if the event is a valid hotcue drag or drop event.
+/// Event must be a QDragEnterEvent or a QDropEvent.
+/// In case of QDropEvent, the HotcueDragInfo is extracted and the pointer
+/// data is used by the caller (WHotcueButton) to swap hotuces.
+template<typename T>
+bool isValidHotcueDragOrDropEvent(T* pEvent,
+        QObject* pTarget,
+        const QString& group,
+        int ignoreHotcueIndex,
+        HotcueDragInfo* pDragData = nullptr);
+
+} // namespace hotcuedrag
+
+} // namespace mixxx

src/widget/whotcuebutton.cpp

@@ -1,5 +1,7 @@
 #include "widget/whotcuebutton.h"
 
+#include <widget/hotcuedrag.h>
+
 #include <QApplication>
 #include <QDrag>
 #include <QDragEnterEvent>
@@ -18,10 +20,9 @@
 
 namespace {
 constexpr int kDefaultDimBrightThreshold = 127;
-const QString kDragDataType = QStringLiteral("hotcueDragInfo");
 } // anonymous namespace
 
-WHotcueButton::WHotcueButton(const QString& group, QWidget* pParent)
+WHotcueButton::WHotcueButton(QWidget* pParent, const QString& group)
         : WPushButton(pParent),
           m_group(group),
           m_hotcue(Cue::kNoHotCue),
@@ -190,8 +191,9 @@ void WHotcueButton::mouseMoveEvent(QMouseEvent* pEvent) {
 
         // Use the currently rendered button as dnd cursor
         // (incl. hover and pressed style).
-        // Note: for some reason, both grab() and render() render with sharp corners,
-        // ie. qss 'border-radius' is not applied to the drag image.
+        // Note: both grab() and render() use the pure rect(),
+        // i.e. these render with sharp corners and qss 'border-radius'
+        // is not visible in the drag image.
         const QPixmap currLook = grab(rect().marginsRemoved(m_dndRectMargins));
         pDrag->setDragCursor(currLook, Qt::MoveAction);
 
@@ -207,39 +209,30 @@ void WHotcueButton::mouseMoveEvent(QMouseEvent* pEvent) {
 }
 
 void WHotcueButton::dragEnterEvent(QDragEnterEvent* pEvent) {
-    TrackPointer pTrack = PlayerInfo::instance().getTrackInfo(m_group);
-    if (!pTrack) {
-        return;
-    }
-    QByteArray mimeDataBytes = pEvent->mimeData()->data(kDragDataType);
-    if (mimeDataBytes.isEmpty()) {
-        return;
-    }
-    HotcueDragInfo dragData = HotcueDragInfo::fromByteArray(mimeDataBytes);
-    if (dragData.isValid() &&
-            dragData.trackId == pTrack->getId()) {
+    if (mixxx::hotcuedrag::isValidHotcueDragOrDropEvent<QDragEnterEvent>(
+                pEvent,
+                this,
+                m_group,
+                m_hotcue)) {
         pEvent->acceptProposedAction();
+    } else {
+        pEvent->ignore();
     }
 }
 
 void WHotcueButton::dropEvent(QDropEvent* pEvent) {
-    if (pEvent->source() == this) {
-        pEvent->ignore();
-        return;
-    }
     TrackPointer pTrack = PlayerInfo::instance().getTrackInfo(m_group);
-    if (!pTrack) {
-        return;
-    }
-    QByteArray mimeDataBytes = pEvent->mimeData()->data(kDragDataType);
-    if (mimeDataBytes.isEmpty()) {
-        return;
-    }
-    HotcueDragInfo dragData = HotcueDragInfo::fromByteArray(mimeDataBytes);
-    if (dragData.isValid() &&
-            dragData.trackId == pTrack->getId() &&
-            dragData.hotcue != m_hotcue) {
+    HotcueDragInfo dragData = HotcueDragInfo();
+    if (pTrack &&
+            mixxx::hotcuedrag::isValidHotcueDragOrDropEvent<QDropEvent>(
+                    pEvent,
+                    this,
+                    m_group,
+                    m_hotcue,
+                    &dragData)) {
         pTrack->swapHotcues(dragData.hotcue, m_hotcue);
+    } else {
+        pEvent->ignore();
     }
 }
 

src/widget/whotcuebutton.h

@@ -2,44 +2,14 @@
 
 #include <QString>
 
-#include "track/trackid.h"
 #include "util/parented_ptr.h"
 #include "widget/wcuemenupopup.h"
 #include "widget/wpushbutton.h"
 
 class WHotcueButton : public WPushButton {
     Q_OBJECT
-
-    struct HotcueDragInfo {
-        HotcueDragInfo(TrackId id, int cue)
-                : trackId(id),
-                  hotcue(cue) {};
-
-        static HotcueDragInfo fromByteArray(const QByteArray& bytes) {
-            QDataStream stream(bytes);
-            TrackId trackId;
-            int hotcue;
-            stream >> trackId >> hotcue;
-            return HotcueDragInfo(trackId, hotcue);
-        };
-
-        QByteArray toByteArray() {
-            QByteArray bytes;
-            QDataStream dataStream(&bytes, QIODevice::WriteOnly);
-            dataStream << trackId << hotcue;
-            return bytes;
-        };
-
-        bool isValid() {
-            return trackId.isValid() && hotcue != Cue::kNoHotCue;
-        }
-
-        TrackId trackId = TrackId();
-        int hotcue = Cue::kNoHotCue;
-    };
-
   public:
-    WHotcueButton(const QString& group, QWidget* pParent);
+    WHotcueButton(QWidget* pParent, const QString& group);
 
     void setup(const QDomNode& node, const SkinContext& context) override;
 
@@ -60,7 +30,6 @@ class WHotcueButton : public WPushButton {
     void mouseMoveEvent(QMouseEvent* pEvent) override;
     void dragEnterEvent(QDragEnterEvent* pEvent) override;
     void dropEvent(QDropEvent* pEvent) override;
-
     void restyleAndRepaint() override;
 
   private slots:

src/widget/wpushbutton.h

@@ -75,7 +75,6 @@ class WPushButton : public WWidget {
     void focusOutEvent(QFocusEvent* e) override;
     void fillDebugTooltip(QStringList* debug) override;
 
-  protected:
     virtual void restyleAndRepaint();
 
     // Associates a pixmap of a given state of the button with the widget