Qt: use guarded pointer for adding grid items to layout, in case playlist is changed (and hence the items get deleted) before they are all added

ui/drivers/qt/flowlayout.cpp

@@ -55,13 +55,14 @@
 #include <QtWidgets>
 
 #include "flowlayout.h"
+#include "../ui_qt.h"
 
 FlowLayout::FlowLayout(QWidget *parent, int margin, int hSpacing, int vSpacing)
    : QLayout(parent), m_hSpace(hSpacing), m_vSpace(vSpacing)
 {
    setContentsMargins(margin, margin, margin, margin);
 
-   connect(this, SIGNAL(signalAddWidgetDeferred(QWidget*)), this, SLOT(onAddWidgetDeferred(QWidget*)), Qt::QueuedConnection);
+   connect(this, SIGNAL(signalAddWidgetDeferred(QPointer<ThumbnailWidget>)), this, SLOT(onAddWidgetDeferred(QPointer<ThumbnailWidget>)), Qt::QueuedConnection);
 }
 
 FlowLayout::FlowLayout(int margin, int hSpacing, int vSpacing)
@@ -226,18 +227,22 @@ int FlowLayout::smartSpacing(QStyle::PixelMetric pm) const
    else if (parentObj->isWidgetType())
    {
       const QWidget *pw = static_cast<const QWidget*>(parentObj);
-      return pw->style()->pixelMetric(pm, 0, pw);
+      return pw->style()->pixelMetric(pm, NULL, pw);
    }
    else
        return static_cast<const QLayout*>(parentObj)->spacing();
 }
 
-void FlowLayout::addWidgetDeferred(QWidget *widget)
+void FlowLayout::addWidgetDeferred(QPointer<ThumbnailWidget> widget)
 {
    emit signalAddWidgetDeferred(widget);
 }
 
-void FlowLayout::onAddWidgetDeferred(QWidget *widget)
+void FlowLayout::onAddWidgetDeferred(QPointer<ThumbnailWidget> widget)
 {
+   /* widget might have been deleted before we got to it since this uses a queued connection, hence the guarded QPointer */
+   if (!widget)
+      return;
+
    addWidget(widget);
 }

ui/drivers/qt/flowlayout.h

@@ -63,6 +63,8 @@
 #include <QRect>
 #include <QStyle>
 
+class ThumbnailWidget;
+
 class FlowLayout : public QLayout
 {
    Q_OBJECT
@@ -83,13 +85,13 @@ public:
    void setGeometry(const QRect &rect);
    QSize sizeHint() const;
    QLayoutItem* takeAt(int index);
-   void addWidgetDeferred(QWidget *widget);
+   void addWidgetDeferred(QPointer<ThumbnailWidget> widget);
 
 signals:
-   void signalAddWidgetDeferred(QWidget *widget);
+   void signalAddWidgetDeferred(QPointer<ThumbnailWidget> widget);
 
 private slots:
-   void onAddWidgetDeferred(QWidget *widget);
+   void onAddWidgetDeferred(QPointer<ThumbnailWidget> widget);
 
 private:
    int doLayout(const QRect &rect, bool testOnly) const;

ui/drivers/qt/ui_qt_window.cpp

@@ -126,7 +126,8 @@ static void scan_finished_handler(void *task_data, void *user_data, const char *
 #endif
 
 GridItem::GridItem() :
-   widget(NULL)
+   QObject()
+   ,widget(NULL)
    ,label(NULL)
    ,hash()
    ,image()
@@ -545,6 +546,8 @@ MainWindow::MainWindow(QWidget *parent) :
    QAction *viewTypeListAction = NULL;
    int i = 0;
 
+   qRegisterMetaType<QPointer<ThumbnailWidget> >("ThumbnailWidget");
+
    viewTypePushButton->setObjectName("viewTypePushButton");
    viewTypePushButton->setFlat(true);
 
@@ -2895,13 +2898,13 @@ void MainWindow::removeGridItems()
 {
    if (m_gridItems.count() > 0)
    {
-      QMutableListIterator<GridItem*> items(m_gridItems);
+      QMutableVectorIterator<QPointer<GridItem> > items(m_gridItems);
 
       m_pendingItemUpdates.clear();
 
       while (items.hasNext())
       {
-         GridItem *item = items.next();
+         QPointer<GridItem> item = items.next();
 
          if (item)
          {
@@ -3003,8 +3006,8 @@ void MainWindow::addPlaylistItemsToGrid(const QString &pathString)
    for (i = 0; i < items.count(); i++)
    {
       const QHash<QString, QString> &hash = items.at(i);
-      GridItem *item = new GridItem();
-      ThumbnailLabel *label = NULL;
+      QPointer<GridItem> item (new GridItem());
+      QPointer<ThumbnailLabel> label;
       QString thumbnailFileNameNoExt;
       QLabel *newLabel = NULL;
       QSize thumbnailWidgetSizeHint(screenSize.width() / 8, screenSize.height() / 8);

ui/drivers/ui_qt.h

@@ -31,6 +31,7 @@
 #include <QFutureWatcher>
 #include <QPixmap>
 #include <QImage>
+#include <QPointer>
 
 extern "C" {
 #include <retro_common_api.h>
@@ -65,12 +66,14 @@ class ThumbnailWidget;
 class ThumbnailLabel;
 class FlowLayout;
 
-struct GridItem
+class GridItem : public QObject
 {
+   Q_OBJECT
+public:
    GridItem();
 
-   ThumbnailWidget *widget;
-   ThumbnailLabel *label;
+   QPointer<ThumbnailWidget> widget;
+   QPointer<ThumbnailLabel> label;
    QHash<QString, QString> hash;
    QImage image;
    QPixmap pixmap;
@@ -394,7 +397,7 @@ private:
    FlowLayout *m_gridLayout;
    QWidget *m_gridWidget;
    QScrollArea *m_gridScrollArea;
-   QList<GridItem*> m_gridItems;
+   QVector<QPointer<GridItem> > m_gridItems;
    QWidget *m_gridLayoutWidget;
    QSlider *m_zoomSlider;
    int m_lastZoomSliderValue;
@@ -406,6 +409,8 @@ protected:
    void keyPressEvent(QKeyEvent *event);
 };
 
+Q_DECLARE_METATYPE(QPointer<ThumbnailWidget>)
+
 RETRO_BEGIN_DECLS
 
 typedef struct ui_application_qt